UNIVERSITY OF NAIROBI
SCHOOL OF ENGINEERING
DEPARTMENT CIVIL AND CONSTRUCTION ENGINEERING
GEOTECHNICAL ENGINEERING INVESTIGATION REPORT FOR PROPOSED
RESIDENTIAL HOUSING UNITS AT KAKAMEGA TOWNSHIP.
(CASE STUDY SHI-YUNZI IN KAKAMEGA CENTRAL DISTRICT)
BY:
PAMELA ATIENO OYUGI
F16/36075/2010
SUPERVISOR:
Dr. SIMPSON OSANO
FINAL YEAR PROJECT 2015
DECLARATION
I declare that this research project is my original work and has not been presented in any other
university.
Sign………………………………………………
Date………………………………
PAMELA ATIENO OYUGI
F16/36075/2010
This research project has been submitted for examination with my approval as the University
Supervisor.
Sign………………………………………………
Date………………………………
Dr. SIMPSON OSANO
Supervisor
University of Nairobi
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ABSTRACT
One of the first stages of any project is to commission a site investigation to determine the nature
of the soil conditions. This will determine whether the site is suitable for the proposed structure
and enable the type and cost of foundations to be determined.
Conditions of the site should be known in advance so as to provide the interested parties with
adequate information for optimal decisions to be made concerning methods that should be used
in the exploration exercise.
In this project samples of soils were taken from 5trial pits and tests to determine engineering
properties were conducted in the laboratory. The tests carried out were; consolidation tests, soil
compaction test, shear box test, particle size distribution and atterberg limits. With the aim of
determining the soils safe bearing capacity and making recommendations on type of foundation
to be used together with other beneficial recommendations that can be used throughout the
construction process.
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DEDICATION
I dedicate this report to my loving parents, Johnson Oyugi and Elizabeth Oyugi to whom I’m
deeply indebted and grateful for their continuous support throughout my social and academic
life.
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ACKNOWLEDGEMENTS
An undertaking of this magnitude cannot be successfully achieved by the unilateral efforts of one
individual. I would wish to express my sincere gratitude first and foremost to God for His divine
guidance throughout my five years in campus, my supervisor Dr. (Eng.) Simpson Osano for his
assistance and advice during the execution of this project and finally to the technicians in the soil
mechanics laboratory who went out of their way to assist me finish my tests as scheduled.
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TABLE OF CONTENTS
DECLARATION ............................................................................................................................ ii
ABSTRACT ................................................................................................................................... iii
DEDICATION ............................................................................................................................... iv
ACKNOWLEDGEMENTS ............................................................................................................ v
LIST OF TABLES ......................................................................................................................... ix
LIST OF FIGURES ........................................................................................................................ x
CHAPTER ONE: INTRODUCTION ......................................................................................... 1
1.1 General Introduction ............................................................................................................. 1
1.2Site Description ...................................................................................................................... 2
1.3 Problem Statement ................................................................................................................ 3
1.4Scope and Objectives of Study............................................................................................... 3
1.5 Expected Output .................................................................................................................... 3
CHAPTER TWO: LITERATURE REVIEW ............................................................................ 4
2.1 Overview ............................................................................................................................... 4
2.2 Soil in Natural State .............................................................................................................. 4
2.2.1 Soil Genesis .................................................................................................................... 5
2.2.2 Soil Mass Structure ......................................................................................................... 6
2.3 Soil Description and Classification ....................................................................................... 7
2.3.1 Soil Description Details .................................................................................................. 8
2.3.2 Soil Classification ........................................................................................................... 8
2.4 Soil Compaction .................................................................................................................. 10
2.4.1 Moisture Content – Dry Density Relationship ............................................................. 11
2.4.2 Effect of Compactive Effort ......................................................................................... 12
2.4.3 Laboratory Compaction Test ........................................................................................ 13
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2.4.4 In-situ or Field Compaction .......................................................................................... 13
2.5 Soil Properties ..................................................................................................................... 13
2.5.1 Permeability .................................................................................................................. 13
2.5.2 Compressibility............................................................................................................. 14
2.5.3 Strength ......................................................................................................................... 14
2.5.4 Texture .......................................................................................................................... 14
2.5.5 Soil Stress ..................................................................................................................... 15
2.5.6 Soil Density ................................................................................................................ 15
2.6 Soil Consistency .................................................................................................................. 15
2.6.1 Atterberg Limits ........................................................................................................... 16
2.7 Geotechnical Exploration Exercise ..................................................................................... 17
2.7.1 Desk Study.................................................................................................................... 17
2.7.2 Site Reconnaissance ..................................................................................................... 17
2.7.3 Ground Investigation .................................................................................................... 18
2.8 Geology ............................................................................................................................... 20
2.9 Consolidation ...................................................................................................................... 22
2.10 Bearing Capacity ............................................................................................................... 22
2.11 Soil Mechanics and Foundation Engineering.................................................................... 23
CHAPTER THREE: METHODOLOGY ................................................................................ 25
3.1 Desk Study .......................................................................................................................... 25
3.2 Site Investigation ................................................................................................................. 25
3.3 Laboratory Tests .................................................................................................................. 27
3.3.1 Shear box ...................................................................................................................... 27
3.3.2 Sieve Analysis .............................................................................................................. 28
3.3.3 Hydrometer Analysis .................................................................................................... 29
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3.3.4 Proctor Compaction Test .............................................................................................. 30
3.3.5 Determination of the One-Dimension Consolidation Properties .................................. 31
CHAPTER FOUR: RESULTS, ANALYSIS AND DISCUSSION ......................................... 35
4.1 Soil Description and Classification ..................................................................................... 35
4.2 Strength Tests ...................................................................................................................... 35
CHAPTER FIVE: CONCLUSION AND RECOMMENDATION ........................................ 39
5.1 Conclusion........................................................................................................................... 39
5.2 Recommendations ............................................................................................................... 39
REFERENCES ............................................................................................................................. 41
Appendix A: Summary of Laboratory Results and Analysis........................................................ 42
Appendix B: Trial Pit Logs ........................................................................................................... 69
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LIST OF TABLES
Table 2-1: Soil Plasticity Index Ranges ........................................................................................ 16
Table 2-2: Bearing Capacity Ranges of Soils ............................................................................... 23
Table 4-1: classification according to particle size distribution………………………………...34
Table 4-2: Summary of Compaction Test Analysis ...................................................................... 36
Table 4-3: Bearing Capacity Table ............................................................................................... 38
Table 5-1: Recommended Bearing Capacity ................................................................................ 40
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LIST OF FIGURES
Figure 2.1: Single Grain Structure .................................................................................................. 6
Figure 2.2: ASTM Sieve Stack and Mechanical Shaker ................................................................. 9
Figure2.3: Apparatus for Hydrometer Analysis............................................................................ 10
Figure 2.4: Dry Density–Water Content Relationship .................................................................. 11
Figure 2.5: Dry Density–Water Content Curves For Different Compactive Efforts ..................... 12
Figure 3-1: Sample of Trial Pits.................................................................................................... 25
Figure 3-2: Extraction of Undisturbed Sample ............................................................................. 26
Figure 3-3: Washing of Test Sample ............................................................................................ 29
Figure 3-4 Casagrande Odometers Apparatus .............................................................................. 32
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CHAPTER ONE: INTRODUCTION
1.1 General Introduction
Geotechnical engineering is concerned with the multidiscipline coordination of mechanics,
material properties, fluid flow, environmental effects and both soil and rocks.
Geotechnical engineering also has a variety of applications such as;

Foundation engineering-involves design of foundation for structures including
buildings, walls and embankments

Geo-environmental engineering–involves assessment prevention and mitigation of
ground and surface water pollution from landfills, lagoons and hazardous wastes

Highway engineering and engineering of dams
A geotechnical site investigation is the process of collecting information and evaluating the
conditions of the site for the purpose of designing and constructing the foundation for the
structure. Therefore a geotechnical engineer is called on to predict the behavior and
performance of soil as a construction material or as a support for engineered works.
A geotechnical site investigation is an essential part of the preliminary design work on any
important structure in order to obtain information regarding the sequence of strata and the
ground water level, and also to collect samples for identification and testing. In addition a site
investigation is often necessary to assess the safety of an existing structure or to investigate a
case where failure has occurred.
The geotechnical site investigation processes include;

Soil sampling – which can either be disturbed samples or undisturbed
samples
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Augering

Boring –boreholes are drilled to determine geological properties of soil.

Use of test or trial pits
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1.2 Site Description
The project is aiming at investigating a site in Shi-yunzi, Kakamega Central District in
Western Kenya which is 6.8km from kakamega town, where residential housing units are to
be constructed on a ten acres piece of land (40468.56𝑚2 ). The site can be accessed through
the kakamega –mumias road for about 5.3km from kakamega town and then branching to an
all weathered road for about 1.5km.
The terrain is steep in most parts but fairly gentle in most parts. Slopes vary from steep
dissected slopes (5-15º) on relatively hard, fine grained silty clay loamy soils to fairly steep
slopes (10-25º) sloping towards an existing river with a swampy area lying on the downhill
side. Vegetation cover consisted of grass and undergrowth on the gentle slopes and tress along
the river banks.
Boulders and rock outcrops exist on the upper part of the hill, and disappear entirely within
the area under investigation. This is an indication that there is a hard stratification at shallow
to deep depths. A general view photograph of the area is shown below.
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1.3 Problem Statement
Defining subsurface conditions that influence the sitting, design and performance of a project
to identify underground features and conditions, characterizing their physical properties and
delineating their vertical and lateral extent.
1.4 Scope and Objectives of Study
geotechnical properties of soil such as its grain size distribution,plasticity,compressibility and
shear strength are assessed by proper laboratory test while emphasis is placed on the in-situ
determination of strength deformation of soil properties because the process avoids disturbing
samples during field exploration.
The ultimate aim of geotechnical engineering is to assess enough information to select the
most appropriate foundation solution to outline problems that could arise during construction
and on a more general scale, to highlight potential geological hazards in the examined area as
well as to:

Determine the location and variation in the ground water table checking whether it
is in the zone of design interest or not.

Evaluate the load bearing capacity of the soil.

Determine location of bedrock.

Determine and design the type and depth of foundation for a given structure.

Prepare a geotechnical investigation report for the proposed building which will
include; a summary of field investigation results and observations, laboratory test
results, boreholes location plan and geotechnical engineering recommendations for
the design and construction of the project.
Both disturbed and undisturbed samples were obtained to estimate the engineering properties
for strength, stability and water flow.
1.5Expected Output
The investigation provides data on surface and underground conditions at the proposed site
and samples may be obtained for visual inspection and to determine physical and index
properties.
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CHAPTER TWO: LITERATURE REVIEW
2.1 Overview
A site investigation or soil survey is an essential part of the preliminary design work on any
important structure in order to obtain information regarding the sequence of strata and the
ground water level and also to collect samples for identification and testing. No rules
regarding the location of boreholes or drill holes or the depth to which they should be sunk.
This depends upon two principal factors, the geological conditions and type of project
concerned. The design of foundation, an earth dam or retaining wall cannot be made in an
intelligent and satisfactory manner unless the designer has at least a reasonably accurate
conception of the physical properties of the soils involved .the field and laboratory
investigation required to obtain this essential information constitutes of geotechnical
investigation. geotechnical site investigation may form part of a feasibility study or is
undertaken to assess the suitability of a site and the surroundings for a proposed engineering
structure as such it involves investigating the ground conditions at and below the surface. The
data obtained from a, investigation for a feasibility study is used to help determine whether
the project is feasible. An investigation carried out prior to the construction of an engineering
project is a pre-requisite for the successful and economic design of engineering structures and
earthworks. The complexity of a site investigation depends upon nature of ground conditions
and type of engineering structure concerned. More complicated ground conditions and more
sensitive large engineering structures require more rigorous investigation of the ground
conditions. Although site investigation usually consist of three stages namely; desk study, a
preliminary reconnaissance and a site investigation, there must be a degree of flexibility in the
procedure since no two sites are the same.
2.2 Soil in Natural State
Using engineering aspects, wide practically unlimited range of soils can be found in nature, from
hard pieces of rocks through gravel, sand and clay to organic sediments of compressible peat.
Therefore, soils in pits can have highly variable properties and the estimation of these properties
highly depend on the soil genesis of that particular area.
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The following can be found

residual soil that originated from weathering in a place and have not been transported

Sediments- soils that have been transported from one place of their origin to another via
transport media.

Man-made sediments - sediments created by activity of man as a result of deposition of
different extracted soils or waste material on the earth’s surface.
2.2.1Soil Genesis
In principle, soil make up the top layer of the earths’ crust from orders of meters to tens of
meters and exceptionally even to hundreds of meters in some place. The remaining part of the
earths’ crust is made up of rocks with thickness of about 25-50km.The earths’ surface is not
constant, huge changes are going on with time. Geology describes these changes and classifies
them with respect to time in the form of names, geological groups and eras. Atkinson (1993)
states in brief, that the materials of Cenozoic age are generally regarded as soils for engineering
purposes; materials of the Mesozoic age are generally regarded as soft rocks and materials of the
paleozoicage are regarded as hard rocks.
Geological evolution on the earth is still going on and it is possible to describe it using a closed
geological cycle: denudation deposition- sediment formation-crustal movements. Individual
processes can be described as follows, Vanicek (1982a). Denudation covers all processes that
contribute to the removal of top layer of the earths’ crust.
The most important process is weathering. It’s a process which includes all destructive
mechanical, chemical and biological processes that disturb the existing composition of the
earths’ surface. The weathering process is connected with erosion and transport of weathered
products by different means (gravity, water, wind) from one area to the other. Deposition
describes the process of accumulation of transported mass. Sediment formation describes the
processes by the influence of which accumulated sediments are hardened. Crustal movements
include slow (epirogenetic) movements, generated by unloading of areas (uplift) or by loading
from new sediments (downthrown) as well as rapid d movements (tectonic movements). From
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the above mentioned it is obvious that the character of soils and their behavior will be influenced
mainly by weathering, type of transport and sedimentation rate.
2.2.2 Soil Mass Structure
The orientation of particles in a mass depends on the size and shape of the grains as well as upon
the minerals of which the grains are formed. The structure of soils that is formed by natural
deposition can be altered by external forces. Figure 2.1 gives the various types of structures of
soil. Fig. 2.1 is a single grained structure which is formed by the settlement of coarse grained
soils in suspension in water. Figure 2.1(a) is a dispersed structure formed by the deposition of
the fine soil fraction in water. Figure 2.1(b) is a flocculated structure particles are oriented in a
flocculent structure will have edge-to-face contact. Book house structure which is formed by the
disintegration of a flocculent structure under a superimposed load as shown in Figure 2.1(c)
whereas in a honeycomb structure, the particles will have face-to-face contact as shown in Figure
2.1(d). Natural clay sediments will have more or less flocculated particle orientations as shown
in figure 2.1(e).
Figure 2.1: Single Grain Structure
Figure 2.1 Clay structures: (a) dispersed, (b) flocculated, (c) book house and (d) honeycomb;
(e) Example of natural clay.
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2.3Soil Description and Classification
It is essential that a standard language should exist for the description of soils. A Comprehensive
description should include the characteristics of both the soil material and the in-situ soil mass.
Material characteristics can be determined from disturbed samples of the soil, i.e. samples having
the same particle size distribution as the in-situ soil but in which the in-situ structure has not
been preserved. The principal material characteristics are particle size distribution or (grading)
and plasticity, from which the soil name can be deduced. Particle size distribution and plasticity
properties can be determined either by standard laboratory tests or by simple visual and manual
procedures. Secondary material characteristics are the color of the soil and the shape, texture and
composition of the particles.
Mass characteristics should ideally be determined in the field but in many cases they can be
detected in undisturbed samples, i.e. samples in which the in-situ soil structure has been
essentially preserved. A description of mass characteristics should include an assessment of insitu compactive state (coarse soils) or stiffness (fine soils) and details of any bedding,
discontinuities and weathering. The arrangement of minor geological details, referred to as the
soil macro-fabric, should be carefully described, as this can influence the engineering behavior
of the in-situ soil to a considerable extent. Examples of macro-fabric features are thin layers of
fine sand and silt in clay, silt-filled fissures in clay, small lenses of clay in sand, organic
inclusions and root holes. The name of the geological formation, if definitely known, should be
included in the description; in addition, the type of deposit may be stated (e.g. till, alluvium, river
terrace), as this can indicate, in a general way, the likely behavior of the soil. It is important to
distinguish between soil description and soil classification.
Soil description includes details of both material and mass characteristics, and therefore it is
unlikely that any two soils will have identical descriptions. In soil classification, on the other
hand, a soil is allocated to one of a limited number of groups on the basis of material
characteristics only.
Soil classification is thus independent of the in-situ condition of the soil mass. If the soil is to be
employed in its undisturbed condition, for example to support a foundation, a full soil description
will be adequate and the addition of the soil classification is discretionary. However,
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classification is particularly useful if the soil in question is to be used as a construction material,
for example in an embankment. Engineers can also draw on past experience of the behavior of
soils of similar classification.
2.3.1 Soil Description Details
A detailed guide to soil description is given in BS 5930 [3]. According to this standard the basic
soil types are boulders, cobbles, gravel, sand, silt and clay, added to these are organic clay, silt or
sand, and peat. These names are always written in capital letters in a soil description. A soil is of
basic type sand or gravel termed as coarse soils if, after the removal of any cobbles or boulders,
over 65%of the material is of sand and gravel sizes.
A soil is of basic type silt or clay termed as fine soils if, after the removal of any cobbles or
boulders, over 35% of the material is of silt and clay sizes. However, these percentages should be
considered as approximate guidelines, not forming a rigid boundary. Sand and gravel may each
be subdivided into coarse, medium and fine fractions. The state of sand and gravel can be
described as well graded, poorly graded, and uniform or gap graded. In the case of gravels,
particle shape (angular, sub-angular, sub-rounded, rounded, flat, elongated) and surface texture
(rough, smooth, polished) can be described if necessary. Particle composition can also be stated.
Gravel particles are usually rock fragments such as sandstone and schist. Sand particles usually
consist of individual mineral grains such as quartz and feldspar.
Fine soils should be described as either silt or clay: terms such as silty clay should not be used.
Fine soils containing 35–65% coarse material are described as sandy and/or gravelly silt or clay.
Deposits containing over 50%of boulders and cobbles are referred to as very coarse and normally
can be described only in excavations and exposures. Mixes of very coarse material with finer
soils can be described by combining the descriptions of the two components, e.g. cobbles with
some finer material (sand); gravelly sand with occasional boulders.
2.3.2 Soil Classification
According to the texture or the “feel,” two different soil types can be identified. The coarsegrained soils include gravel and sand and fine-grained soils silt and clay. While the engineering
properties primarily strength and compressibility of coarse-grained soils depend on the size of
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individual soil particles, the properties of fine-grained soils are mostly governed by the moisture
content. Hence, it is important to identify the type of soil at a given construction site since
effective construction procedures depend on the soil type. Geotechnical engineers use a universal
format called the unified soil classification system (USCS) to identify and label different types of
soils.
The system is based on the results of common laboratory tests of mechanical analysis which is
conducted in two stages:

Sieve analysis for the coarse fraction (gravel and sand)

Hydrometer analysis for the fine fraction (silt and clay).
2.3.2.1 Sieve Analysis
Conducted according to American Society for Testing and Materials (ASTM) D421 and D422
procedures, using a set of U.S. standard sieves. During the test, the percentage by weight of the
soil sample retained on each sieve is recorded, from which the percentage of soil passing through
a given sieve size is determined. On the other hand, if a substantial portion of the soil sample
consists of fine-grained soils (D<0.075mm), then sieve analysis has to be followed by
hydrometer analysis.
Figure 2.2: ASTM Sieve Stack and Mechanical Shaker
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2.3.2.2 The Hydrometer Analysis
Test is performed by first treating the “fine fraction” with a deflocculating agent such as sodium
hexametaphosphate or sodium silicate in a water glass for about half a day and then allowing the
suspension to settle in a hydrometer jar kept at a constant temperature. As the heavier particles
settle, followed by the lighter ones, a calibrated ASTM 152H hydrometer is used to estimate the
fraction that is still settling above the hydrometer bottom at any given stage.
Figure2.3: Apparatus for Hydrometer Analysis
2.4Soil Compaction
Soil compaction is a process whereby the soil particles are forced into a closer state of packing
with a corresponding reduction in volume and the expulsion of air. Vibrations due to traffic
movement, heavy machinery and certain construction operations such as pile driving have been
known to cause compaction settlement. In earthquake zones, seismic shock waves may have
similar effects.
In practice, soils of medium cohesion are compacted by means of rolling, while cohesionless
soils are most effectively compacted by vibration. Prior to the advent of rolling equipment, earth
fills were usually allowed to settle over a period of years under their own weight before the
pavement or other construction was placed. (C.Venkatramaiah).The degree of compaction of a
soil is characterized by its dry density and it depends upon the moisture content, the amount of
compactive effort or energy expandable and the nature of soil. A change in moisture content or
compactive effort brings about change in density.
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The following are the important effects of compaction:

Compaction increases the dry density of soil, thus increasing its shear strength and
bearing capacity through an increase in frictional characteristics.

Compaction decreases the tendency for settlement of soil

Compaction brings about a low permeability of the soil
2.4.1 Moisture Content – Dry Density Relationship
The addition of water to a dry soil helps in bringing the solid particles together by coating them
with thin films of water. At low water content, the soil is stiff and it is difficult to pack it together
and as the water content is increased, water starts acting as a lubricant, the particles start coming
closer due to increased workability and under a given amount of compactive effort, the soilwater- air mixture starts occupying less volume, thus effecting gradual increase in dry density.
As more and more water is added, a stage is reached when the air content of the soil attains a
minimum volume, thus making the dry density a maximum. The water content corresponding to
this maximum dry density is called the ‘optimum moisture content’ but the addition of water
beyond the optimum reduces the dry density because the extra water starts occupying the space
which the soil could have occupied. Below is the relationship between moisture content and dry
density of a soil at a particular compaction energy or effort………
Figure 2.4: Dry Density–Water Content Relationship
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The curve is known as the compaction curve and the state at the peak is that of 100% compaction
at a particular compactive effort. The wet density and the moisture content are required in order
to calculate the dry density as follows:
ᵧ
ᵞ𝑑 = 1+𝑤
Where; ᵞ𝑑 = 𝑑𝑟𝑦𝑑𝑒𝑛𝑠𝑖𝑡𝑦
ᵞ = 𝑤𝑒𝑡(𝑏𝑢𝑙𝑘)𝑑𝑒𝑛𝑠𝑖𝑡𝑦
𝑤 = 𝑤𝑎𝑡𝑒𝑟𝑐𝑜𝑛𝑡𝑒𝑛𝑡
2.4.2 Effect of Compactive Effort
Increase in compactive effort or the energy expanded will result in an increase in the maximum
dry density and a corresponding decrease in the optimum moisture content as illustrated below
Figure 2.5: Dry Density–Water Content Curves For Different Compactive Efforts
Thus for purpose of standardization, especially in the laboratory, compaction test are conducted
at a certain specific amount of compactive effort expended in a standard manner.
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2.4.3 Laboratory Compaction Test
The compaction characteristics namely dry density and the optimum moisture content are first
determined in the laboratory. It is then specified that the unit weight achieved through
compaction in the field should be a certain high percentage of the laboratory value, for quality
control of the construction.
The various procedures used in the laboratory compaction tests involve application of impact
loads, kneading, static loads, or vibration. The primary objective of these tests is to arrive at a
standard which may serve as a guide and a basis for comparison of what is achieved during
compaction in the field.
2.4.4 In-situ or Field Compaction
The compacted dry density to be attained for a given fill is specified on basis of laboratory
compaction test. The standard proctor test or the modified A.A.S.H.T.O. test may be used
depending on the size of equipment proposed to be used. As control in the field cannot be as
rigid as in the laboratory, the specifications usually require attainment of 95% or more of the dry
density attained in the laboratory. Thus control of compaction in the field requires the
determination of the in-situ unit weight of the compacted fill and also the moisture content.
The methods available for the determination of in-situ unit weight are: sand replacement method,
core-cutter method, volumenometer method, nuclear method, rubber balloon method and proctor
plastic needle method.
2.5Soil Properties
These are the inherent physical characteristics in a soil that are derived as a function of the
genesis of soil and that determine its behavior under a stress, when it is used as a resource or
as a foundation in an engineered work.
2.5.1 Permeability
Permeability of a soil is a measure of the ease with which a particular fluid flows through its
voids, usually the flow of water through soils. Permeability of a soil can be measured in either
the laboratory or the field; laboratory methods are much easier than field methods. Field
determinations of permeability are often required because permeability depends very much
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both on the microstructure-the arrangement of soil-grains and on the macrostructure-such as
stratification, and also because of the difficulty of getting representative soil samples.
2.5.2 Compressibility
Soils subjected to increased load decrease in volume.
2.5.3 Strength
The strength of soil materials is a variable and elusive property.
a) Cohesive soils
These soils generally contain sufficient clay content to effectively glue the mass together.
They also have the ability to be molded and shaped which is known as plasticity and also
describes the ability of the soil to be rolled into thin rod 3.0mm diameter without breaking.
These soils have internal growth, can be compacted and compressed and are generally
suitable for foundation materials under optimum content.
b) Non cohesive soils
These soils have no strength of their own and there is usually a completely absence of clay or
fine particles from which cohesion is derived. Examples of such soil include sand and gravel.
However, if sandy or gravely soils are geologically or structurally confined they can exhibit
strength properties but the strength is done to confinement, not the material itself.
2.5.4 Texture
Soil texture is a property that is similar to that used in the description of sedimentary rocks
and includes attributes of;

Particle size – describes the physical dimension of individual particles and is derived
by sieving the soil and plotting the results on log paper. Value is obtained are used to
determine soil strength and tells the engineer what percent of soil contains what size of
grains

Shape – It’s a description of the equidimensional attributes of the particle

Roundness – this property specifies angularity at the particle edges and corners
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o Size, shape and roundness all contribute to how a soil sample will sieve out.
Shape may prevent a grain from passing a sieve in one direction but if the
particle is turned on end, it might pass that sieve. Sieve data are plotted on log
paper for analysis and it forms a curve that contains characteristics that are
used to describe that particular soil.
2.5.5 Soil Stress
A soil under the surface will be under stress due to the weight of the overlying material, such
that there will be a force acting on an area increasing with depth and is supported by two
separate components of the soil.
a) Effective Stress (s) – is the measure for the portion of the total stress that is borne by
grain-to-grain soil matrix
b) Pore water pressure (u) – Is the measure of the portion of the total stress borne by the
water existing between the pores.
It can be concluded that as depth increases, the pore water pressure becomes less (if it is
dewatered by the compaction) and the effective stress will increase as compaction and
dewatering of sediments occur. Total stress is equal to summation of effective stress and pore
water pressure.
2.5.6 Soil Density
This is the ratio of mass to volume of a soil. In simpler terms, it is a measure of the heaviness ofs
oil. The density of soils is determined according to ASTM D85400, Standard Test Methods forSpe
cific Gravity of Soils by Water Pycnometer.The density of the soils is used in the calculation of so
il particle size distribution as specified inASTM D422-63.
2.6Soil Consistency
This is the ease to which soil can be deformed. It is strongly influenced by the size of particles
present in the soil and the water content. Most granular soils are not affected by consistency
properties however; fine-grained soil can deform readily which may have important
implications if the soil is to be used in engineering works. Consistency of soil is evaluated
through.
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2.6.1 Atterberg Limits
2.6.1.1 Plastic Limit
This is the water content where a soil begins to behave as a plastic solid and the soil can be
rolled into a thin thread 3mm diameter before breaking. The higher the clay content the lower
the plastic limit. (PL)
2.6.1.2 Liquid Limit
This is the water content under which a soil begins to exhibit a liquid behavior. It will not
flow readily but will act as vicious liquid. In engineering work, soils are generally not useful
at the liquid limit (LL)
2.6.1.3 Plastic Index
Describes the range of plastic behavior and is found as a difference between the LL and PL
Plastic Index (PI) = Liquid Limit (LL) – Plastic Limit (PL)
Plasticity Index (PI)
Non-plastic
0
Slightly plastic
0–5
Low plasticity
5 – 20
Medium plasticity
10 – 20
High plasticity
20 – 40
Very high plasticity
> 40
Table 2-1: Soil Plasticity Index Ranges
2.6.1.4 Liquidity Index
A measure of the soils sensitivity in respect to the soil response to sudden shear forces, such
as vibrations and earthquakes.
At LI = 1.0, the soil exhibits liquid properties and so is very sensitive while at L.I = 0.0
indicates a soil at the plastic limit and soil is no longer sensitive.
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𝐿𝑖𝑞𝑢𝑖𝑑𝑖𝑡𝑦𝐼𝑛𝑑𝑒𝑥(𝐿𝐼) =
Where;
𝑊𝑛 − 𝑃𝐿
𝑃𝐼
wn – water content in natural conditions
PL – Plastic Limit
PI – Plastic Index
2.7 Geotechnical Exploration Exercise
Exploration exercise refers to the procedure of determining surface and subsurface conditions
in an area of proposed construction. Information regarding surface conditions is necessary for
planning construction technique while information on subsurface conditions enable the
engineer to draw the soil profile indicating the characteristics of soil properties at different
depths. The exercise includes:
o Desk study
o Site reconnaissance
o Ground investigation
2.7.1 Desk Study
It is the first step in an exploration exercise and involves collecting published information
about the site under investigation and pulling it all together to build a conceptual model of the
site. Most of the information gathered at desk study stage is contained in maps, published
reports and aerial photographs. A study of the site geology is also important at this stage.
2.7.2 Site Reconnaissance
Reconnaissance involves an inspection of the site and study of the topographical features
which will yield useful information about the soil and ground water conditions and also help
the engineer plan the programme of ground investigation. The topography, drainage pattern,
vegetation and land use provide valuable information.
Reconnaissance investigation gives a preliminary idea of the soil and other conditions
involved at the site and its value should not be underestimated. Further study may be avoided
if reconnaissance reveals the inadequacy or unsuitability of the site for the proposed work for
any glaring reasons.
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2.7.3 Ground Investigation
The methods available for soil exploration may classify as follows:
o Direct methods – test pits, trial pits and trenches
o Semi-direct methods - borings
o Indirect methods- soundings or penetration tests and geophysical methods
2.7.3.1 Test Pits
A test pit is a hole dug in the ground that is large enough for a ladder to be inserted thus
permitting a close examination of the sides. They are normally limited to a depth not more
than 3m and are more suitable where load bearing strata is at shallow depth allowing in-situ
soil conditions such as stratification be observed directly. Disturbed and undisturbed samples
can be taken from the sides and bottom of the pit at any orientation that may be required.
2.7.3.2 Borings
Boring is making or drilling boreholes into the ground with a view of obtaining soil or rock
samples from specified or known depths. Methods of advancing boreholes are:
Auger boring
In auger boring, the hole is advanced by rotating a soil auger while pressing it into the soil and
as the auger gets filled with soil, it is taken out and the soil sample collected. Augers may be
hand-operated or power-driven, the former are used for relatively small depths less than 3 to
5m while the latter are used for greater depths.
Wash boring
Wash boring is commonly used for exploration below ground water table for which the auger
method is unsuitable
Percussion drilling
A heavy drill bit called churn bit is suspended from a drill or a cable and is driven by repeated
blows. Water is added to facilitate the breaking of stiff soil or rock and the slurry of the
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pulverized material is bailed out at intervals. The method cannot be used in loose sand and is
slow in plastic clay.
Rotary drilling
This method is fast in rock formations. A drill bit fixed to the lower end of a drill rod is
rotated by power while being kept in firm contact with the hole and a drilling fluid or
bentonite slurry is forced under pressure through the drill rod and it comes up bringing the
cuttings to the surface.
2.7.3.3 Sampling
Soil sampling is the process of obtaining samples of soil from the desired depth at the desired
location in a natural soil deposit, with a view to assessing the engineering properties of the
soil for ensuring a proper design of the foundation. Either disturbed or undisturbed samples
can be obtained from this process
Disturbed samples
A disturbed sample is that which the natural structure of the soil gets modified partly or fully
during sampling.
Undisturbed samples
Samples in which the materials have been subjected to so little disturbance that it is suitable
for all laboratory tests, including shear strength and consolidation test. A truly undisturbed
sample is a fiction since all samples are disturbed to a greater or smaller degree.
2.7.3.4 Sounding and Penetration Tests
Soundings are used for exploring soil strata of an erratic nature and are useful to determine
the presence of any soft pockets between drill holes and also to determine the density index of
cohesionless soils and the consistency of cohesive soils at various desired depths from the
ground surface. Sounding normally consist of driving or pushing a standard sampling tube or
a cone.
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2.8 Geology
The Kakamega District is in the South East quadrant bounded by the equator and latitude
0030’N and longitude 35000’E. The site in study is fifteen kilometers south east of Kakamega
Township. The general geology of the district consists of intrusive (mainly granites),
NyanzianVolcanics and the Kavirondian sediments. However, the granites cover most parts of
the district. Kakamega area comprises of rocks of the Pre-Cambrian basement system, the
Tertiary lavas - Mt. Elgon volcanics and the Recent lateritic and the black cotton soil.
The area is mainly covered by basalts which are highly epitomized and where they occur as
roof pendants in granites, a considerable degree of recrystallization and often shearing is
noticed. Though their widest development is in the area east of Malaba, where they do not
normally form conspicuous outcrops and much of the area is underlain by basalts is covered
with a thick, deep red, rather clayey soil.
In hand-specimen they are dense,fine-grained,dark green rocks in which only occasionally are
minute feldspar crystals recognizable to the unaided eye. Outcrops are normally blocky due to
strong joint development.
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Map1: The Geology of Kenya
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2.9 Consolidation
The application of stress to any material will cause a corresponding strain. For other common
construction material such as steel or wood, the strain occurs simultaneously with the stress
application. In contrast fine-grained soils will usually exhibit a measureable time lag between the
application of a stress and the resulting strain. Therefore, consolidation is slow change in height
caused by time-lag necessary to permit water flow out of a loaded soil mass.
Observations show that when a load is applied to a soil, the volume of the soil decreases since
the individual soil grains are for all practical purposes in-compressible at the load intensities
applied to the soil mass. The change in volume must be due to a decrease in the volume of voids
which is accompanied by a rearrangement of the soil grains and a compression of the material in
the void. If the soil is dry, the voids are air-filled and since air is compressible the rearrangement
of the soil grains can occur rapidly. If the soil is saturated, the voids are filled with
incompressible water and water must flow out of the soil mass before the soil grains can
rearrange themselves and in soils of low permeability this process requires long time interval for
completion hence the strain occurs very slowly.
According to terzaghi’s theory of consolidation the following conditions are assumed;

Homogenous soil

Complete saturation

Incompressible water and soil grains

Compression and flow in one direction

Action of differential soil mass similar to the action of large soil mass

Linear relationship between pressure and void ratio
2.10 Bearing Capacity
Capacity in bearing capacity indicates that it is an ultimate concept and hence it is not a safe or
working or allowable quantity. Bearing capacity refers to the ultimate, the maximum load the
soil can bear or sustain under given circumstances. Therefore, it involves the application of loads
to the soil for which a medium such as a footing is needed whose role is to invoke the property
latent in the soil called its bearing capacity. The bearing capacity of soil is concerned with
strength of soil and not that of footing. Therefore, in all bearing capacity discussions only
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footings which are infinitely rigid and which can bring about the failure of soil without itself
failing are considered. In other words the footing just plays the role of a medium to load the soil.
SOIL TYPE
BEARING
CAPACITY(𝑲𝑵⁄𝒎𝟐 )
Dense gravel or sand and > 600
gravel
Medium dense gravel or sand
200 – 600
and gravel
Loose gravel or sand and < 200
gravel
Dense sand
> 300
Medium dense sand
100 - 300
Loose sand
< 100
Very stiff and hard clays
300 - 600
Stiff clays
150-300
Firm clays
75 - 150
Soft clays and silts
< 75
Very soft clays and silt
<<< 75
REMARKS
B should not be less than 1m.
Water table below foundation
level.
Long
term
settlement
consolidation
Table 2-2: Bearing Capacity Ranges of Soils
2.11 Soil Mechanics and Foundation Engineering
Foundations pass the total load from a structure to the ground by direct contact. The load from
the superstructure reaches the foundation by means of a number of individual units such as
columns or walls and it is the function of the foundation to distribute the load in such a
manner that the ground is neither over stretched nor caused to settle more than the
superstructure can conveniently accommodate. Karl Terzaghi’s writing in 1951 “the influence
of modern soil studies on the design and construction of foundations” commented on
foundations as follows;
“Foundations can appropriately be described as a necessary evil. If a building is to be
constructed on an outcrop of sound rock, no foundation is required .hence in contrast
to the building itself which satisfies specific needs, appeals to the aesthetic sense and
fills its matters with pride, the foundations merely serves as a remedy for the
deficiencies of whatever whimsical nature has provided for the support of the
structure at the site which has been selected. On account that there is no glory
attached to the foundations and that the sources of success or failures are hidden in
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the ground, building foundations have always been treated as step children and their
acts of revenge for the lack of attention can be very embarrassing.”
During design the designer has to make use of properties of soil, the theories pertaining to design
and his own practical experience to adjust the design to suit field conditions. Natural soil
deposits which perform the engineering function of supporting the foundation and superstructure
above it has to be dealt with. The soil deposits in nature are available in an extremely erratic
manner producing thereby an infinite variety of possible combinations which would affect the
choice and design of foundations. So the foundation engineer must have the ability to interpret
the principles of soil mechanics to suit the field conditions. The success or failure of a design
will depend on how much the designer is in tune with nature.
Design of foundations of structures requires knowledge of factors such as:

The load that will be transmitted by the superstructure to the foundation system.

Requirements of local building codes.

Geological conditions of soil under consideration.

Behavior and stress-related deformability of soils that will support the foundation
system.
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CHAPTER THREE: METHODOLOGY
The methodology used in this study comprised of:

Desk study

Reconnaissances

Site investigation
3.1 Desk Study
It involved collecting information on the area of study from published reports, journals and
geological maps. The information from all this sources gave a general background of
Kakamega, the types of soil variation and the terrain of the area.
3.2 Site Investigation
The location of the TPs and BHs was marked on the site. Excavation of the TPs was conducted
manually up to 1.5m depths. Samples were recovered, both undisturbed and disturbed for
laboratory investigations
Figure 3-1: Sample of Trial Pits
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Disturbed Samples
Great care and precision was observed to ensure that disturbed samples were true representative
of the stratum. These samples were satisfactory for performng classification and strength tests.
Undisturbed Samples
The true in-situ structure and water content of the soil was achieved using several samples of
undisturbed nature. Core cutter apparatus was used to recover these samples. They were useful
indetermining reliable information on the shearing resistance and stress-deformation
characteristics of the soils.
Figure 3-2: Extraction of Undisturbed Sample
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3.3 Laboratory Tests
The following described tests were carried out in the laboratory to help in classification and
also to determine properties of the soil samples collected.

Sieve analysis

Hydrometer analysis

Direct shear (shear box)test

Consolidation test

Compaction test

Atterberg limits
All laboratory tests were carried out in accordance to the BS 1377-part2:1990 (BRITISH
STANDARDS) except for the compaction test which was carried out in accordance to
A.A.S.T.H.O standards.
3.3.1 Shear box
Scope
To measure the shear strength of a soil variation in the load applied normal to the plane of shear.
Apparatus

Constant rate strain- shear box apparatus. The box is made up of brass and is 6cm square
by 4cm deep. It is open at top and bottom and is divided horizontally into two halves
which can be accurately fixed by screws passing vertically through the walls of the upper
half to screw into the lower.

Two toothed perforated brass grids 6cm square to fit into the shear box.

Two porous sintered square stones 6 cm square to fit into the box.

A proving ring with dial gauge.

A metal pressure pad which fits into the box and distributes the load from a yoke over the
sample, normal to the shear plane. Yoke bears upon the loading cap through steel ball.

Weights for loading the yoke

Moisture content test apparatus
Procedure
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The top half of the shear box was screwed on top of the bottom half and then placed in the
container. The top half of the box was in contact with the proving ring.
The porous stone was then placed at the bottom followed by a toothed grid set with its serrations
at right angles to the direction of shear. The sample was placed in shear box.
The upper toothed grid was then placed on top of the sample again with the serrations at right
angles to the direction of the shearing plane. The upper porous stone and the pressure pad were
then placed.
Normal load was then applied by placing weights on the yoke. 32.2, 68.9 and 105 kgs were used
in the test. The vertical screws were then removed.
The motor was then started noting the proving ring dial when the sample was sheared. The motor
was then closed.
Three samples were tested and the readings were entered in a laboratory sheets provided. The
values of C and ∅ were then calculated.
3.3.2Sieve Analysis
Scope
Method covers the quantative determination of distribution of particles sizes larger than 75μm
(retention sieve No.200).
Apparatus

Balance

Set of Sieves from 3/8 in –No.200

Tray

oven
Procedure
Sample Preparation
200g of oven dried disturbed sample was soaked in a dish for about 20minutes to soften the soil.
After which the sample was poured into a washing tray and washed thoroughly until it was clear,
underneath was placed sieve No.200 which was used to collect finer particles from the wash
water. The sample on the sieve was then added to the washed sample and oven-dried for
24hours.
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Figure 3-3: Washing of Test Sample
Test sample
The set of sieves was arranged in such a way that every upper sieve had a larger opening than the
sieve below it.
The remaining oven dried sample after washing was taken and transferred on the top sieve and
the set of sieves was shaken for about 10minutes.
The test sieves were agitated so that the soil sample rolled in a regular motion over the sieves.
After the soil was agitated, the soil retained on each sieve was weighed on the balance and mass
retained recorded. From the total mass retained it was checked whether hydrometer analysis was
necessary on the soil (i.e. if 40% passed sieve No.200).
3.3.3 Hydrometer Analysis
The hydrometer method is used to determine the distribution of the finer particles.
The smaller size fractions, silt and clay both of which pass the 75μm (#200) sieve, are
determined by hydrometer analysis.
Apparatus
I.
II.
A calibrated hydrometer
Two 1000ml graduated glass measuring cylinders
III.
A thermometer, readable and accurate to 0.5°C
IV.
A mechanical shaker
V.
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VI.
A stop watch
VII.
A wash bottle
VIII.
A conical flask
IX.
A glass rod
Procedure
a) The soil sample provided had been pretreated and dispersed.
b) The soil sample was placed in a measuring cylinder. Water was added into the measuring
cylinder. A rubber bang was inserted in the mouth of the measuring cylinder and it was
shaken vigorously until a uniform suspension was formed. Immediately the shaking
ceased, the measuring cylinder was allowed to stand and the stop watch started. The
hydrometer was immersed to a depth slightly below its floating position and then allowed
to float freely.
c) Hydrometer readings were taken after periods of ½ min, 1min, 2min and 4min. the
hydrometer was then slowly removed, rinsed in distilled water and kept in the cylinder of
distilled water at the same temperature as the soil suspension.
d) The hydrometer was re-inserted in the measuring cylinder and readings taken after
periods of 8min, 15min, 30min, 1hr, 2hrs and 4hrs. The hydrometer was removed, placed
in the distilled water. After 4hrs, the reading was taken at 20hrs and at 24hrs.
3.3.4 Proctor Compaction Test
Objective
To determine the maximum dry density and optimum moisture content
Theory
The optimum water content is the water content that results in the greatest density for a specified
compactive effort. This method covers the determination of the dry density of soil when
compacted over a range of moisture contents .the method is applicable to soils containing not
less than 90% passing the 3⁄4 in (19mm) B.S.sieve.
The method is also known as the dynamic compaction test.
Apparatus

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
Manual rammer weighing 2.5kg

Extruder, Balance, Drying oven,

Mixing pan, Trowel, ¾ inch sieve,

Moisture cans,

Graduated cylinder,

Straight Edge.
Procedure
An air dried sample was prepared to provide about 20kg of soil passing the ¾ in B.S sieve and 6
subsamples weighed each weighing about 3kg
The samples were mixed with different amounts of water to give suitable range of moisture
content. The mould with the base plate was weighed W1 and the collar attached
Each sub sample was compacted into the mould in 3layers of equal weight each layer being
given 25blows from the rammer dropped above the soil
The collar was removed and the excess soil trimmed off and the mould, base plate and soil
specimen contained weighed W2
The specimen was extruded from the mould and a fraction of it taken for moisture determination
m the same procedure was repeated for other subsample with different water content.
3.3.5 Determination of the One-Dimension Consolidation Properties
Theory
This method covers the determination of magnitude and rate of the consolidation of saturated or
near-saturated specimen of soil in the form of disc confined laterally, subjected to vertical axial
pressure, and allowed to drain freely from the top to the bottom surfaces. The main purpose of
the consolidation test on soil samples is to obtain the necessary information about the
compressibility properties of a saturated soil for use in determining the magnitude and rate of
settlement of structures. The following test procedure is applied to any type of soil in the
standard consolidation test.
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Figure 3-4Casagrande Odometers Apparatus
Consolidation apparatus
The consolidation apparatus was the fixed ring type and consisted of the following:
1) A metal consolidation ring of high grade stainless steel, which was completely and
rigidly confined and supported the soil specimen laterally.
2) Porous plates for placing at the top and bottom surfaces of the test specimen e.g. sintered
fused aluminum oxide, sintered bronze or similar material.
3) A consolidation cell of suitable material within which is placed the best specimen
assembly consisting of the test specimen held within the consolidation ring and between
the top and the bottom porous plates and resting centrally on, the base of the cell
4) A micrometer dial gauge or other device, which is called the compression gauge,
supported for measuring the vertical compression or swelling of the specimen
throughout the test. The gauge was read to support 0.002mm and had at least 6mm
travel.
5) A loading device having a rigid bed for supporting the consolidation cell. The device
enabled vertical force to be applied axially in suitable increments to the test specimen
through a suitable loading yoke.
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Procedure
Preparation of test specimen. The test specimen was prepared as follows:
(1) A short length of the soil sample was extruded from sample tube by means of the jack
and frame and examined for soil type.
(2) A consolidation ring of suitable dimensions and watch glass was cleaned, dried, and
weighed separately. The ring was then lubricated slightly with silicone grease. The
extruded length of sample was cut off flush with end of the tube using the thin bladed
trimming knife
The procedure was as follows.
1. A representative sample for testing was extruded and cut off, care being taken to ensure that
the two plane faces of the disc of soil are parallel to each other. The thickness of the disc of
soil was somewhat greater than the height of the consolidation ring.
2. When an undisturbed sample was received in the form of an excavated block, a disc of
similar size to the above was cut from the block with two parallel faces, care being taken to
ensure that the soil stratum is oriented in the appropriate direction in the consolidation
apparatus (The laboratory test should normally compress the soil in the same direction
relative to the soil stratum as the applied force in the field.)
3. Using the consolidation ring as a template the edges of the disc was trimmed carefully over
the soil; the last fraction of soil being pared a way by cutting edge of the as it was pushed
down slowly and evenly over the sample, with no unnatural voids against the inner face of
the ring. The thickness of the consolidation specimen was measured and the specimen in its
ring was placed on the watch glass or metal tray and weighed immediately.
4. A reading of the gauge and the time was noted.
Loading sequence:
UNLOADING
On completion of the compression gauge readings under the maximum applied pressure, the load
was removed from the test specimen and the consolidation cell removed from the apparatus. The
mass of the watch glass, or metal tray was checked. The specimen in its ring was then removed
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from the cell, the filter papers taken off the specimen, and the whole transferred to the oven on
the watch glass or metal tray.
The specimen was dried in the oven to constant mass.
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CHAPTER FOUR: RESULTS, ANALYSIS AND DISCUSSION
The analysis covers test results from five trial pit logging which are: Tp 2,5,8,13,18.
4.1 Soil Description and Classification

Particles Size Distribution
Test results for particle size distribution are summarized in appendix A. sampling was done
within 1.5m-2.0m and soils were predominantly clayey SAND. The trial pit logs as shown in
appendix B shows that there is existence of a top 0.2-0.5m depth of loose darkish clay loamy soil
underlain by stiff yellowish clayey SAND strata.
Water oozed out from some of the trial pits at shallow depths, near the swampy area indicating
that there is existence of shallow water table within the vicinity of these trial pits.
Trial pit
Soil type
2TP3
Silty SAND
2TP5
Silty clayey SAND
2TP8
Silty clayey SAND
2TP13
Silty clayey SAND
2TP18
Silty clayey SAND
Table 4-1: classification according to particle size distribution

Atterberg Limits
The materials are classified using the unified soil classification system and the test results are as
shown in Appendix A.As deduced the soils are generally classified as SC and CH (clayey sands
and inorganic clays of high plasticity) since the plasticity index (PI) of the soil ranges between
15 – 40.
(Ref to table 2-1)
4.2 Strength Tests

Compaction Tests
This was used to obtain the moisture content of soil and also the dry density of the soil.
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Trial pit No.
OMC
MDD (kg/m3
2Tp3
17.1%
1696.1
2Tp5
14.5%
1752.1
2Tp8
13.9%
1770.3
2Tp13
15.5%
1721.1
2Tp 18
13.2%
1810.4
Table 4-2: Summary of Compaction Test Analysis
From the laboratory test results graphs of dry density against moisture content were plotted as
shown in appendix A which indicated maximum dry density ranging between 1696.1kg/m3 and
1810kg/m3 with corresponding Optimum moisture content (OMC) ranging between 13.2 and
17.1%.

Bulk density
The bulk density ranged between 1414 and 1735kg/m3, with MDD ranging between 86-98%.

Shear Box test
The summary of test results is tabulated in appendix A. using the results from laboratory a graph
of shear stress against normal stress was plotted to obtain the shear strength parameters c and ϕ
𝑙𝑜𝑎𝑑 𝑎𝑝𝑝𝑙𝑖𝑒𝑑
Normal stress (δ) =𝑎𝑟𝑒𝑎 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑎𝑚𝑝𝑙𝑒
Shear stress (ῖ)=
𝑝𝑟𝑜𝑣𝑖𝑛𝑔 𝑟𝑖𝑛𝑔 𝑑𝑖𝑣∗𝑟𝑖𝑛𝑔 𝑓𝑎𝑐𝑡𝑜𝑟
𝑎𝑟𝑒𝑎 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒
Therefore values of shear strength can also be obtained from the equation below;
Shear strength = c + δ tan ϕ
The results show that cohesion ranged from 0.07 to 0.13
𝑘𝑔⁄
𝑐𝑚2 while angle of internal friction
ranged from 23 to 25 degrees, indicating that the soils are very stiff in nature.
P.A.O
Page 36
FINAL YEAR PROJECT 2015

Consolidation
The values used in the following analysis are results obtained in the consolidation test which are
attached in appendix A. This corresponds to low to medium compressibility, shrinkage and
swell.
TRIAL PITS
BULK DENSITY
(kg/m3 )
VOLUME
OF CEOFFICIENT
OF
CONSOLIDATION
COMPRESSIBITY(𝑚2 /𝑀𝑁)
(𝑚2 /Year)
2TP 5
2TP18
1680
1700
0.22
0.233

0.514
0.203
Ultimate bearing capacity of foundation- bell’s method
The classical earth pressure theory assumes that on exceeding a certain stress condition, rapture
surfaces are formed in the soil. The stress developed upon the formation of the rapture surfaces is
treated as the ultimate bearing capacity of the soil. The bearing capacity may be determined from
the relation between the principal stresses at failure.
Bell (1915) developed a formula applicable for cohesive soils i.e. soils having both cohesion and
friction, as is case with Kakamega soils. From Bell’s Bearing Capacity Equation (1915) for c – ϕ
soils the following equation can be applicable to compute the ultimate bearing capacity of soil
samples.
𝑞𝑢 = 𝛾𝐷𝑁∅ 2 + 2∁√𝑁∅ (1 + 𝑁∅ )
ϕ – Angle of internal friction (degrees)
Where:
𝑞𝑢− Ultimate bearing capacity (𝐾𝑁⁄𝑚2 )
D -Depth
𝛾 −Bulk density (𝐾𝑁 ⁄𝑚3 )
∅
𝑁∅ - 𝑡𝑎𝑛2 (45 + 2)
By replacing the parameters from shear strength results, the safe bearing capacity of the soils
were computed as show
P.A.O
Page 37
FINAL YEAR PROJECT 2015
Trial
Depth
Cohesion,
Pit
(m)
Ф deg
Bulk
Ultimate
Factor
Safe
C
Density
Bearing
of
Bearing
(𝑲𝑵⁄𝒎𝟐 )
(𝑲𝑵⁄𝒎𝟑 ) Capacity,𝒒𝒖 Safety
Capacity
(𝑲𝑵⁄𝒎𝟐 )
TP2
1.5
13
23
14.16
181
3
60
TP5
1.5
8
26
16.23
207
3
69
TP8
1.5
10
25
17.13
213
3
71
TP18
1.5
13
25
17.00
229
3
76
Table 4-2: Bearing Capacity Table
The results as tabulated gave an ultimate bearing capacity ranging from 181 to 229𝐾𝑁⁄𝑚2 with
safe bearing capacity ranging between60-80 𝐾𝑁⁄𝑚2 these showed that the soil type is stiff
clays. (Ref to table 2-2)
P.A.O
Page 38
FINAL YEAR PROJECT 2015
CHAPTER FIVE: CONCLUSION AND RECOMMENDATION
5.1 Conclusion
This purpose of this study was to investigate the properties of soil on this site for the proposed
residential building. The main objective of the study was to determine the bearing capacity of the
soil. The study was successful in:

Classifying the soil

Determining the bearing capacity

Determining whether the soils bearing capacity was sufficient for the proposed structure.
The soil was generally classified as stiff clays with safe bearing capacity ranging between 6080𝐾𝑁⁄𝑚2 .
The footings that support a residential house usually require a minimum allowable soil bearing
capacity of 75𝐾𝑁⁄𝑚2 . Generally, excavations to undisturbed soil below the layer of topsoil of
>1.5m shall provide the required 75𝐾𝑁⁄𝑚2 . At 2m and beyond, the bearing capacity increases
considerably, and values >191𝐾𝑁⁄𝑚2 are obtained. A higher factor of safety of three was used
so as to incorporate sesmic loads being that kakamega is situated on an area of sesmic hazards.
A natural variation that may affect the construction of the structure is rainfall but to avoid its
interference site clearance and excavation of trenches can be done during dry season.
It is therefore safe to conclude that the study was a success.
5.2 Recommendations
Recommended
Allowable
depth(m)
capacity(𝐾𝑁⁄𝑚2 )
Up to 1.5
60
bearing
Foundation soil type
Recommended foundation type
(estimated settlement<25mm)
Medium dense
Not recommended
Clayey Silt Sand
1.5 – 2.0
87
Medium dense
PAD/RAFT
Clayey Silt Sand
2.0 – 3.0
191
Dense GravelSand
PAD/RAFT
3.0 – 3.5
227
Dense GravelSand
PAD/RAFT
4.5 – 5.0
234
Dense GravelSand
STRIP/PAD
P.A.O
Page 39
FINAL YEAR PROJECT 2015
Table 5-1: Recommended Bearing Capacity
The foundation depths to be adopted for the engineering structure to be put up within the project
area are as shown above. I would recommend foundation depth of 1.7m (average of 1.5 and 2.0)
below the ground level with allowable ground end bearing capacity of 87𝐾𝑁⁄𝑚2 .
Kakamega area is based in an area of medium seismic hazard therefore structural design of
substructure should take care of these expected vibrations and incorporate earthquake loads.
The topsoil should be removed during grading and may be stockpiled and re-used for nonstructural areas only, such as landscaping. Reusing this material as backfill soil for sub-grade
support is not recommended.
P.A.O
Page 40
FINAL YEAR PROJECT 2015
REFERENCES
Geotechnical Engineering (Basics of Soil Mechanics), S. Chand & Company Ltd, NewDelhi.
Foundation Engineering Handbook, CBS Publishers & Distributors, New Delhi.
Vanicek, I.&Vanicek, M.Earth Structures In Transport, Water and Environmental Engineering.
Schroeder.W.L, Soils in construction (1975), published in Canada.
Venkatramaiah, C. (2006). Geotechnical Engineering 3rd edition.
Bharat Singh & Shamsher P. (1981). Soil Mechanics and Foundation Engineering 5thEdition.
Geotechnical Investigation (2014 August) http://en.wikipedia.org/w/index.php
www.usbr.gov/pmts/geology/geolman chap 3.pdf
Singh. A, (1990). Soil Engineering in Theory and Practice vol 2, 2nd edition.
BS 1377:1990 soils for civil engineering
P.A.O
Page 41
FINAL YEAR PROJECT 2015
APPENDIX A: SUMMARY OF LABORATORY RESULTS AND ANALYSIS
UNIVERSITY OF NAIROBI
SOIL MECHANICS LABORATORY
SOIL COMPACTION BY THE 2.5KG RAMMER METHOD
SOIL TYPE:
TESTED BY: OYUGI P A
WEIGHT OF MOULD: 4120g
VOLUME OF MOULD: 0.956
NO.OF LAYERS: 3
NO.OF BLOWS PER LAYER: 25
SAMPLE NO: 2TP 3
TEST NO
1
2
3
4
WT OF MOULD +
5730
5830
6000
6015
WET
MATERIAL
(G)
WT
WET
1610
1710
1880
1895
MATERIAL (G)
WET
DENSITY
3
1684.1004 1788.7029 1966.527197 1982.2176
(KG/M )
(N.M.C)
MOISTURE CONTENT DETERMINATION
CONTAINER NO
197A
184A
68A
107A
WT
OF
220.20
197.60
259.40
208.10
CONTAINER + WET
MATERIAL (G)
WT
OF
74.50
75.30
88.40
91.00
CONTAINER (G)
WT
OF
214.10
189.00
242.10
192.90
CONTAINER + DRY
MATERIAL (G)
WT
DRY
139.60
113.70
153.70
101.90
MATERIAL (G)
WT OF MOISTURE
6.10
8.60
17.30
15.20
(G)
MOISTURE
4.37
7.56
11.26
14.92
CONTENT (%)
DRY
DENSITY
1565.68
1607.74
1711.26
(KG/M3)
P.A.O
5
5980
1860
1945.6067
201A
180.30
74.70
163.80
89.10
16.50
18.52
1672.50
Page 42
FINAL YEAR PROJECT 2015
GRAPH OF DRY DENSITY AGAINST MOISTURE CONTENT (%)
1800.00
1750.00
MDD (kg/m3)
1700.00
1650.00
1600.00
1550.00
1500.00
5.0
15.0
25.0
Moisture Content (%)
Optimum Moisture Content = 17.1%
Maximum Dry Density = 1696.1 kg/m3
P.A.O
Page 43
FINAL YEAR PROJECT 2015
UNIVERSITY OF NAIROBI
SOIL MECHANICS LABORATORY
SOIL COMPACTION BY THE 2.5KG RAMMER METHOD
SOIL TYPE:
TESTED BY: OYUGI P A
WEIGHT OF MOULD: 4120g
VOLUME OF MOULD: 0.956
NO.OF LAYERS: 3
NO.OF BLOWS PER LAYER: 25
SAMPLE NO: 2TP 5
TEST NO
WT OF MOULD +
WET MATERIAL
(G)
WT
WET
MATERIAL (G)
WET
DENSITY
3
(KG/M )
(N.M.C)
CONTAINER NO
WT
OF
CONTAINER
+
WET MATERIAL
(G)
WT
OF
CONTAINER (G)
WT
OF
CONTAINER
+
DRY MATERIAL
(G)
WT
DRY
MATERIAL (G)
WT
OF
MOISTURE (G)
MOISTURE
CONTENT (%)
DRY
DENSITY
(KG/M3)
P.A.O
1
2
3
4
5
5790
5975
6060
6030
5950
1670
1855
1940
1910
1830
1746.8619
1940.3766
2029.288703
1997.9079
1914.2259
MOISTURE CONTENT DETERMINATION
121A
13A
108A
92A
156.80
169.60
159.40
141.50
68A
173.80
62A
218.90
14.60
25.50
15.40
17.90
15.00
14.50
149.90
158.00
143.70
124.40
147.50
179.70
135.30
132.50
128.30
106.50
132.50
165.20
6.90
11.60
15.70
17.10
26.30
39.20
5.10
8.75
12.24
16.06
19.85
23.73
1606.24
1728.82
1748.54
1667.02
1547.11
Page 44
FINAL YEAR PROJECT 2015
1800.00
1750.00
MDD (kg/m3)
1700.00
1650.00
1600.00
1550.00
1500.00
5.0
15.0
25.0
Moisture Content (%)
Optimum Moisture Content = 14.5%
Maximum Dry Density = 1752.1 kg/m3
P.A.O
Page 45
FINAL YEAR PROJECT 2015
UNIVERSITY OF NAIROBI
SOIL MECHANICS LABORATORY
SOIL COMPACTION BY THE 2.5KG RAMMER METHOD
SOIL TYPE:
TESTED BY: OYUGI P A
WEIGHT OF MOULD:
VOLUME OF MOULD:
NO.OF LAYERS: 3
NO.OF BLOWS PER LAYER: 25
SAMPLE NO: 2TP 8
TEST NO
WT OF MOULD +
WET MATERIAL
(G)
WT
WET
MATERIAL (G)
WET
DENSITY
3
(KG/M )
(N.M.C)
CONTAINER NO
WT
OF
CONTAINER
+
WET MATERIAL
(G)
WT
OF
CONTAINER (G)
WT
OF
CONTAINER
+
DRY MATERIAL
(G)
WT
DRY
MATERIAL (G)
WT
OF
MOISTURE (G)
MOISTURE
CONTENT (%)
DRY
DENSITY
(KG/M3)
P.A.O
1
2
3
4
5
5705
5915
6020
6065
5970
1585
1795
1900
1945
1850
1657.9498
1877.6151
1987.447699
2034.5188
1935.1464
MOISTURE CONTENT DETERMINATION
1B
35B
209A
184A
195A
98A
268.40
225.40
196.80
166.80
193.40
268.10
77.40
78.60
72.20
75.30
75.00
82.60
263.20
217.60
185.80
156.60
177.20
236.70
185.80
139.00
113.60
81.30
102.20
154.10
5.20
7.80
11.00
10.20
16.20
31.40
2.80
5.61
9.68
12.55
15.85
20.38
1569.86
1711.85
1765.90
1756.15
1607.58
Page 46
FINAL YEAR PROJECT 2015
1800.00
1750.00
MDD (kg/m3)
1700.00
1650.00
1600.00
1550.00
1500.00
5.0
15.0
25.0
Moisture Content (%)
Optimum Moisture Content =13.9%
P.A.O
Page 47
FINAL YEAR PROJECT 2015
Maximum Dry Density = 1770.3 kg/m3
UNIVERSITY OF NAIROBI
SOIL MECHANICS LABORATORY
SOIL COMPACTION BY THE 2.5KG RAMMER METHOD
SOIL TYPE:
TESTED BY: OYUGI P A
WEIGHT OF MOULD: 4120g
NO.OF LAYERS: 3
VOLUME OF MOULD: 0.956
NO.OF BLOWS PER LAYER: 25
SAMPLE NO: 2TP 13
TEST NO
1
2
3
4
WT OF MOULD +
5840
5985
6030
5940
WET
MATERIAL
(G)
WT
WET
1720
1865
1910
1820
MATERIAL (G)
WET
DENSITY
1799.1632 1950.8368 1997.90795
1903.7657
(KG/M3)
(N.M.C)
MOISTURE CONTENT DETERMINATION
106A
106A
198A
209A
CONTAINER NO
WT
OF
270.90
270.90
227.50
242.00
CONTAINER + WET
MATERIAL (G)
WT
OF
106.40
106.40
81.20
72.20
CONTAINER (G)
WT
OF
255.80
255.80
209.60
216.30
CONTAINER + DRY
MATERIAL (G)
WT
DRY
149.40
149.40
128.40
144.10
MATERIAL (G)
WT OF MOISTURE
15.10
15.10
17.90
25.70
(G)
MOISTURE
10.11
10.11
13.94
17.83
CONTENT (%)
DRY
DENSITY
1634.01
1712.15
1695.52
3
(KG/M )
P.A.O
5
216A
272.70
75.60
238.50
162.90
34.20
20.99
1573.43
Page 48
FINAL YEAR PROJECT 2015
1750.00
MDD (kg/m3)
1700.00
1650.00
1600.00
1550.00
5.0
15.0
25.0
Moisture Content (%)
Optimum Moisture Content = 15.5%
Maximum Dry Density = 1721.2 kg/m3
P.A.O
Page 49
FINAL YEAR PROJECT 2015
UNIVERSITY OF NAIROBI
SOIL MECHANICS LABORATORY
SOIL COMPACTION BY THE 2.5KG RAMMER METHOD
SOIL TYPE:
TESTED BY: OYUGI P A
WEIGHT OF MOULD: 4120g
VOLUME OF MOULD: 0.956
NO.OF LAYERS: 3
NO.OF BLOWS PER LAYER: 25
SAMPLE NO: 2TP 18
TEST NO
WT OF MOULD +
WET MATERIAL
(G)
WT
WET
MATERIAL (G)
WET
DENSITY
3
(KG/M )
(N.M.C)
CONTAINER NO
WT
OF
CONTAINER
+
WET MATERIAL
(G)
WT
OF
CONTAINER (G)
WT
OF
CONTAINER
+
DRY MATERIAL
(G)
WT
DRY
MATERIAL (G)
WT
OF
MOISTURE (G)
MOISTURE
CONTENT (%)
DRY
DENSITY
(KG/M3)
P.A.O
1
2
3
4
5
5790
5995
6100
6080
6030
1670
1875
1980
1960
1910
1746.8619
1961.2971
2071.129707
2050.2092
1997.9079
MOISTURE CONTENT DETERMINATION
60B
22B
16B
12B
225A
15B
247.60
221.70
260.00
223.10
224.30
300.60
77.80
81.30
74.40
81.00
72.10
82.20
241.70
212.70
242.40
205.60
201.40
263.10
163.90
131.40
168.00
124.60
129.30
180.90
5.90
9.00
17.60
17.50
22.90
37.50
3.60
6.85
10.48
14.04
17.71
20.73
1634.88
1775.31
1816.06
1741.73
1654.86
Page 50
FINAL YEAR PROJECT 2015
1850.00
1800.00
MDD (kg/m3)
1750.00
1700.00
1650.00
1600.00
5.0
15.0
Moisture Content (%)
Optimum Moisture Content = 13.2%
Maximum Dry Density = 1810.4 kg/m3
P.A.O
Page 51
FINAL YEAR PROJECT 2015
UNIVERSITY OF NAIROBI
SOIL MECHANICS LABORATORY
BULK DENSITY
TESTED BY: OYUGI P A
SAMPLE TYPE: UNDISTURBED SAMPLE
Sample Number
Mass of core cutter
+ Wet soil(g)
Mass
of
core
cutter(g)
Mass of wet soil(g)
Volume of core
cutter(cm3)
Bulk
density
(g/cm3)
Container No.
Mass of wet soil +
Container(g)
Mass of dry soil +
Container(g)
Mass
of
Container(g)
Loss in Moisture
(g)
Mass of Dry soil
Moisture Content
(%)
Dry density(g/cm3)
P.A.O
2 TP 2
2 TP 5
2 TP 7
2 TP 12
2 TP 18
3895
6412
4305
3378
3340
1025
2870
3176
3236
1768
2537
1304
2074
1257
2083
1633
1678
1257
1051
1015
1.758
213
1.928
137
2.018
146
1.973
129
2.052
181
278
310
270.5
322.5
246
242
278
246
286
217.5
92.8
107.7
108.7
109.2
80
36
149.2
32
170.3
24.5
137.3
36.5
176.8
28.5
137.5
24.1
1.416
18.8
1.623
17.84
1.713
20.6
1.636
20.73
1.700
Page 52
FINAL YEAR PROJECT 2015
UNIVERSITY OF NAIROBI
SOIL MECHANICS LABORATORY
ATTERBERG LIMITS: CONE PENETROMETER
SOIL TYPE:
TESTED BY: OYUGI P A
SAMPLE NO: 2TP3
Container number
Initial dial reading
(mm)
Final dial reading
(mm)
Mass of container +
Wet soil, M2 (g)
Mass of container +
Dry soil, M3 (g)
Mass of container,
M1 (g)
Mass of moisture,
(M2-M3) (g)
Mass of dry soil,
(M3-M1) (g)
Moisture content (%)
P.A.O
Z
LIQUID LIMIT
26
8
11
PLASTIC LIMIT
A1
3
0.0
0.0
0.0
0.0
15.5
18
20.3
23.5
58.3
57.5
63.7
55.3
11.4
11.7
45.3
46.4
48.9
44.0
10.8
11
23.1
29.2
27.2
28.5
8.7
8.7
13.0
11.1
14.8
11.3
0.6
0.7
22.2
17.2
21.7
15.5
2.1
2.3
58.6
64.5
68.2
72.9
28.6
30.4
Page 53
FINAL YEAR PROJECT 2015
LIQUID LIMIT
80.0
78.0
76.0
74.0
Moisture Content (%)
72.0
70.0
68.0
66.0
64.0
LIQUID LIMIT = 68%
62.0
60.0
58.0
56.0
54.0
52.0
50.0
15
17
19
21
23
25
Penetration (mm)
P.A.O
Page 54
FINAL YEAR PROJECT 2015
SAMPLE NO: 2TP5
LIQUID LIMIT
Container number
Initial dial reading (mm)
Final dial reading (mm)
Mass of container + Wet
soil, M2 (g)
Mass of container + Dry
soil, M3 (g)
Mass of container, M1
(g)
Mass of moisture, (M2M3) (g)
Mass of dry soil, (M3M1) (g)
Moisture content (%)
PLASTIC LIMIT
26
0.0
15.4
5B
0.0
18
21
0.0
19.6
31
0.0
23.5
1P
O
69
50
59.6
60.4
15.5
15.2
56.5
38.9
49.5
50.0
13.7
13.7
29.3
15.3
28.5
28.8
8.2
8.7
12.5
11.1
10.1
10.4
1.8
1.5
27.2
23.6
21.0
21.2
5.5
5.0
46.0
47.0
48.1
49.1
32.7
30.0
LIQUID LIMIT
50.0
Moisture Content (%)
49.0
48.0
47.0
LIQUID LIMIT = 48%
46.0
45.0
P.A.O
15
17
Penetration (mm)
19
21
23
25Page 55
FINAL YEAR PROJECT 2015
SAMPLE NO: 2TP13
Container number
Initial dial reading (mm)
Final dial reading (mm)
Mass of container + Wet
soil, M2 (g)
Mass of container + Dry
soil, M3 (g)
Mass of container, M1
(g)
Mass of moisture, (M2M3) (g)
Mass of dry soil, (M3M1) (g)
Moisture content (%)
48
0.0
16
LIQUID LIMIT
11
7
0.0
0.0
17
20.3
PLASTIC LIMIT
DD
AI
35
0.0
23.1
81.5
57.9
83.5
69
15.2
16.8
66.1
49.1
66.3
56.1
13.7
15
28.9
28.6
28.4
29.5
8.9
8.9
15.4
8.8
17.2
12.9
1.5
1.8
37.2
20.5
37.9
26.6
4.8
6.1
41.4
42.9
45.4
48.5
31.3
29.5
LIQUID LIMIT
50.0
49.0
48.0
Moisture Content (%)
47.0
46.0
45.0
44.0
43.0
LIQUID LIMIT = 45%
42.0
41.0
40.0
P.A.O
15
17
Penetration (mm)
19
21
23
25
Page 56
FINAL YEAR PROJECT 2015
SAMPLE NO: 2TP18
Container number
Initial dial reading (mm)
Final dial reading (mm)
Mass of container + Wet
soil, M2 (g)
Mass of container + Dry
soil, M3 (g)
Mass of container, M1 (g)
Mass of moisture, (M2M3) (g)
Mass of dry soil, (M3-M1)
(g)
Moisture content (%)
7
0.0
15.1
LIQUID LIMIT
8
E116
0.0
0.0
18
19.8
E119
0.0
22.9
PLASTIC LIMIT
JJ
WX
50.5
68.2
81.9
76.1
16.1
15.5
41.2
56.2
65.0
60.1
14.4
14
17.6
27.3
26.5
25.6
8.6
8.7
9.3
12.0
16.9
16.0
1.7
1.5
23.6
28.9
38.5
34.5
5.8
5.3
39.4
41.5
43.9
46.4
29.3
28.3
LIQUID LIMIT
50.0
49.0
48.0
47.0
Moisture Content (%)
46.0
45.0
44.0
43.0
42.0
LIQUID LIMIT = 44%
41.0
40.0
39.0
P.A.O
38.0
15
17
Penetration (mm)
19
21
23
25
Page 57
FINAL YEAR PROJECT 2015
UNIVERSITY OF NAIROBI
SOIL MECHANICS LABORATORY
PARTICLE SIZE DISTRIBUTION
SOIL TYPE:
TESTED BY: OYUGI P A
SAMPLE NO: 2TP 3
MASS OF SAMPLE: 100gms
MASS OF WASHED DRY SAMPLE: 78.7gms
SIEVE SIZE
(MM)
RETAINED MASS
(GM)
% RETAINED
(%)
20
14
10
5
2.36
1.18
0.6
0.425
0.3
0.15
0.075
0
0
0
3.7
15.7
20.3
19.6
5.2
5.9
5.1
3.2
21.3
100
0.0
0.0
0.0
3.7
15.7
20.3
19.6
5.2
5.9
5.1
3.2
21.3
P.A.O
CUMULATIVE
PASSED
PERCENTAGE (%)
100.0
100.0
100.0
96.3
80.6
60.3
40.7
35.5
29.6
24.5
21.3
Page 58
FINAL YEAR PROJECT 2015
Passing (%)
100
90
80
70
60
50
40
30
20
10
0
0.001
0.01
0.1
1
Sieves (mm)
10
100
SAMPLE NO: 2TP18
MASS OF SAMPLE: 100gms
MASS OF WASHED DRY SAMPLE: 65.9gms
SIEVE SIZE
(MM)
RETAINED MASS
(gm)
% RETAINED
(%)
20
14
10
5
2.36
1.18
0.6
0.425
0.3
0.15
0.075
0
0
0
1
8.2
19.1
17.7
5.1
4.7
5.1
5
34.1
100
0.0
0.0
0.0
1.0
8.2
19.1
17.7
5.1
4.7
5.1
5.0
34.1
P.A.O
CUMULATIVE
PASSED
PERCENTAGE (%)
100.0
100.0
100.0
99.0
90.8
71.7
54.0
48.9
44.2
39.1
34.1
Page 59
FINAL YEAR PROJECT 2015
100
90
80
Passing (%)
70
60
50
40
30
20
10
0
0.001
0.01
0.1
1
10
100
Sieves (mm)
SAMPLE NO: 2TP8
MASS OF SAMPLE: 100gms
MASS OF WASHED DRY SAMPLE: 64.9gms
SIEVE SIZE
(MM)
RETAINED MASS
(gm)
% RETAINED
(%)
20
14
10
5
2.36
1.18
0.6
0.425
0.3
0.15
0.075
0
0
0
2.2
10.3
18.2
15.2
5.5
5
4.3
4.2
35.1
100
0.0
0.0
0.0
2.2
10.3
18.2
15.2
5.5
5.0
4.3
4.2
35.1
P.A.O
CUMULATIVE
PASSED
PERCENTAGE (%)
100.0
100.0
100.0
97.8
87.5
69.3
54.1
48.6
43.6
39.3
35.1
Page 60
FINAL YEAR PROJECT 2015
100
90
Passing (%)
80
70
60
50
40
30
20
10
0
0.001
0.01
0.1
Sieves (mm)1
10
100
SAMPLE NO: 2TP13
MASS OF SAMPLE: 100gms
MASS OF WASHED DRY SAMPLE: 59.8gms
TEST: SIEVE ANALYSIS
SIEVE SIZE
(MM)
RETAINED MASS
(gm)
% RETAINED
(%)
20
14
10
5
2.36
1.18
0.6
0.425
0.3
0.15
0.075
0
0
1.4
4.1
14.6
16.3
5.9
5.1
8.4
4
40.2
100
0.0
0.0
1.4
4.1
14.6
16.3
5.9
5.1
8.4
4.0
40.2
P.A.O
CUMULATIVE
PASSED
PERCENTAGE (%)
100.0
100.0
98.6
94.5
79.9
63.6
57.7
52.6
44.2
40.2
Page 61
FINAL YEAR PROJECT 2015
HYDROMETER ANALYSIS
SAMPLE NO: 2TP 13
MASS OF SAMPLE: 100gms
MASS OF WASHED DRY SAMPLE: 78.7gms
Date
Time
In min
0.5
Temp o
C.
20
Rh1
27.5
Rh
28
HR
9.1
D(mm)
0.0578
K(%)
87
K(corrected)
35
1
2
4
8
15
30
60
120
300
1440
20
20
20
20
20
20
20
20
20
20
26
24.5
22
20.5
18
15.5
13.5
10.5
8
5.5
26.5
25
22.5
21
18.5
16
14
11
8.5
6
9.7
10.3
11.3
11.9
12.9
13.9
14.7
15.9
16.9
17.8
0.0422
0.0307
0.0228
0.0165
0.0126
0.0092
0.0067
0.0049
0.0032
0.0015
83
78
70
65
57
49
42
32
24
16
33
31
28
26
23
20
17
13
10
7
Grading curve-Hydrometer analysis
100
90
Passing (%)
80
70
60
50
40
30
P.A.O
20
10
Page 62
FINAL YEAR PROJECT 2015
SAMPLE NO: 2TP5
MASS OF SAMPLE: 200gms
MASS OF WASHED DRY SAMPLE: 112.3gms
SIEVE SIZE
(MM)
RETAINED MASS
(gm)
% RETAINED
(%)
20
14
10
5
2.36
1.18
0.6
0.425
0.3
0.15
0.075
0
0
1.6
27.2
35.7
21.1
7.3
7
6.3
6.1
87.7
200
0.0
0.0
0.8
13.6
17.9
10.6
3.7
3.5
3.2
3.1
43.9
P.A.O
CUMULATIVE
PASSED
PERCENTAGE (%)
100.0
100.0
99.2
85.6
67.8
57.2
53.6
50.1
46.9
43.9
Page 63
FINAL YEAR PROJECT 2015
HYDROMETER ANALYSIS
SAMPLE NO: 2TP 5
MASS OF SAMPLE: 100gms
MASS OF WASHED DRY SAMPLE: 78.7gms
Date
Time
In min
0.5
Temp o
C.
20
Rh1
27.5
Rh
28
HR
9.2
D(mm)
0.0581
K(%)
87
K(corrected)
38
1
2
4
8
15
30
60
120
300
1440
20
20
20
20
20
20
20
20
20
20
26.5
25
23.5
22
20.5
18.5
16.5
15.5
13
10
27
25.5
24
22.5
21
19
17
16
13.5
10.5
9.6
10.4
10.9
11.4
12
12.8
13.6
14
15
16.3
0.042
0.0309
0.0224
0.0162
0.0121
0.0088
0.0064
0.0046
0.0034
0.0014
84
79
75
70
65
58
52
49
41
31
37
35
33
31
28
26
23
21
18
13
Grading curve-Hydrometer analysis
100
90
Passing (%)
80
70
60
50
40
30
20
10
P.A.O
0
0.001
Page 64
0.01
0.1
1
10
Sieves (mm)
100
FINAL YEAR PROJECT 2015
SHEAR BOX TEST
SAMPLE NO: 2TP2
AREA OF SHEAR BOX: 36𝒄𝒎𝟐
WEIGHT OF HANGER: 4.5KG
Load applied
(kg)
32.2
68.9
105
CALIBRATION FACTOR: 0.0742181kg/div
Total=load+hanger Normal
(kg)
stress=T/A
(kg/𝒄𝒎𝟐 )
36.7
1.02
73.4
2.04
109.5
3.04
Force at failure
(div)
266.78
504.46
683.93
Shear
stress=F*factor/A
(kg/𝒄𝒎𝟐 )
0.55
1.04
1.41
A graph of shear stress against normal stress
3
P.A.O
m2)
2.5
2
Page 65
FINAL YEAR PROJECT 2015
C = 0.13 kg/cm²
Ø = 23°
SAMPLE NO: 2TP5
AREA OF SHEAR BOX: 36𝒄𝒎𝟐
WEIGHT OF HANGER: 4.5KG
Load applied
(kg)
32.2
68.9
105
CALIBRATION FACTOR: 0.0742181kg/div
Total=load+hanger Normal
(kg)
stress=T/A
(kg/𝒄𝒎𝟐 )
36.7
1.02
73.4
2.04
109.5
3.04
Force at failure
(div)
271.63
543.26
751.84
Shear
stress=F*factor/A
(kg/𝒄𝒎𝟐 )
0.56
1.12
1.55
A graph of shear stress against normal stress
3
P.A.O
are cm)
2.5
2
Page 66
FINAL YEAR PROJECT 2015
C
=
0.08
kg/cm
Ø = 26°
SAMPLE NO: 2TP8
AREA OF SHEAR BOX: 36𝒄𝒎𝟐
WEIGHT OF HANGER: 4.5KG
Load applied
(kg)
32.2
68.9
105
Total=load+
hanger
(kg)
36.7
73.4
109.5
CALIBRATION FACTOR: 0.0742181kg/div
Normal
stress=T/A
(kg/𝒄𝒎𝟐 )
1.02
2.04
3.04
Force at failure
(div)
266.78
519.01
717.88
Shear
stress=F*factor/A
(kg/𝒄𝒎𝟐 )
0.55
1.07
1.48
A graph of shear stress against normal stress
3
P.A.O
re cm)
2.5
2
Page 67
FINAL YEAR PROJECT 2015
C = 0.10 kg/cm²
Ø = 25°
SAMPLE NO: 2TP18
AREA OF SHEAR BOX: 36𝒄𝒎𝟐
WEIGHT OF HANGER: 4.5KG
Load applied
(kg)
32.2
68.9
105
CALIBRATION FACTOR: 0.0742181kg/div
Total=load+hanger Normal
(kg)
stress=T/A
(kg/𝒄𝒎𝟐 )
36.7
1.02
73.4
2.04
109.5
3.04
Force at failure
(div)
276.48
548.11
727.59
Shear
stress=F*factor/A
(kg/𝒄𝒎𝟐 )
0.57
1.13
1.50
A graph of shear stress against normal stress
3
P.A.O
e cm)
2.5
Page 68
FINAL YEAR PROJECT 2015
C = 0.13 kg/cm²
Ø = 25°
APPENDIX B: TRIAL PIT LOGS
2TP2
P.A.O
2TP5
Page 69