SOIL MECHANICS AND
FOUNDATION
ENGINEERING-II
(CE 311)
TEXT/ REFERENCE BOOKS
1. SOIL MECHANICS by T WILLIAM LAMBE & ROBERT V.
WHITMAN, Wiley ASTERN
2. FOUNDATION ANALYSIS & DESIGN by JOSEPH E.
BOWLES, Mc Graw Hills
3. GEOTECHNICAL ENGINEERING by SHASHI K GULHATI
& MANOJ DATTA, TATA Mc Graw Hill
4. SOIL MECHANICS AND FOUNDATION ENGINEERING
by B C PUNMIA, A K JAIN & A K JAIN, Laxmi Publications
Pvt. Ltd.
SOIL & ROCK INVESTIGATIONS
 The purpose of the investigation is to find out
what are types of soils and rocks at the site at various locations
as well as various depths.
What are the properties of soils and rocks
The properties can be determined by conducting TESTS IN
THE FIELD or by bringing the soil samples and TESTING IN
THE LABORATORY.
To get samples from different depths or conduct field tests
the BORE HOLES are to be drilled.
SOIL & ROCK INVESTIGATION
(Contd.)
1.
2.
3.
4.
5.
6.
How many bore holes should be drilled?
Where should the bore holes be located?
How deep should the bore hole be?
With what equipment should the bore holes be drilled?
At what depth intervals should soil samples be taken?
What type of samples and sampling techniques should be
used?
7. Which samples should be subjected to laboratory tests?
8. What laboratory tests should be conducted?
9. What field i.e. in-situ tests should be conducted?
10. Where should the in-situ tests be conducted?
SOIL & ROCK INVESTIGATION (Contd.)
INVESTIGATION METHODOLOGIES
 Geophysical and Remote sensing Methods
 Drilling Bore Holes and Sampling
 Pits, Trenches & Shafts
 In-Situ Testing
 Laboratory Testing
INVESTIGATION METHODOLOGIES
GEOPHYSICAL AND REMOTE SENSING METHODS
 Enables us to obtain information about the soil profile by using
the fact that different soils have different resistivities or that a
wave generated by in impact load will travel through different
soils with different velocities. These methods are referred as
Geophysical Methods.
 They are useful when we are interested in obtaining a macro
view of the soil profile over a relatively large area.
 Method based on wave velocity is referred as SEISMIC
METHOD which is useful in determining the depth of various
bedrocks.
 ELECTRICAL RESISTIVITY METHOD is useful in determining
the depth of water below the ground surface.
INVESTIGATION METHODOLOGIES
GEOPHYSICAL AND REMOTE SENSING METHODS (Contd.)
 Interpreting Areal Photographs gives nature of surface soils,
drainage pattern, land use, geological features, topography
etc.
 These are called REMOTE SENSING TECHNIQUES.
INVESTIGATION METHODOLOGIES
DRILLING BORE HOLES AND SAMPLING
 Most powerful technology for site investigation available to
the Consulting Geotechnical Engineer is that of drilling bore
holes, taking samples from various depths and subjecting
them to careful scrutiny and testing in the laboratory.
 Over the years, we have learnt that the process of drilling
and sampling can disturb the soil and that properties
determined using disturbed soil samples can be different
from the properties as they exist in the natural state in the
field.
 This leads to refine the techniques of drilling, sampling,
transporting, storing, retrieving and testing. Thus evolution of
Correction Techniques.
INVESTIGATION METHODOLOGIES
PITS TRENCHES AND SHAFTS
 When we need to investigate only to shallow depths, PITS
are excavated for a close look. Undisturbed soil samples are
taken by simply using hands. Typically, pits have base area
of 1.2 x 1.2 m.
 When bedrock is at shallow depth, TRENCHES can be dug
along the entire length and breadth of the area to determine
the profile of the bedrock as well as to examine the condition
of bedrock.
 In deposits of Cobble and Boulders, large diameter shafts are
excavated to see profile with depth.
INVESTIGATION METHODOLOGIES
IN-SITU TESTING
 In general we can not obtain undisturbed samples of coarse
grained soils such as SAND. Numerous field test have been
developed.
 Some are conducted in the bore holes at different depths.
 Some are conducted without drilling bore holes by merely
pushing PROBES into the soil deposits to desired depths.
 Apart from coarse grained soils, deposits of CLAY having
very high sensitivity are also require In-Situ Testing.
INVESTIGATION METHODOLOGIES
LABORATORY TESTING
 Samples collected from bore holes are carefully sealed
labeled before transporting them to the laboratory.
 This is backbone of the Investigation Methodologies.
 In the laboratory, the Engineer prepares a testing programme
specifying which samples are to be subjected to what tests.
 These tests are used to validate the visual classification as
well as to find both the physical and engineering properties
required for analysis and design.
DRILLING TECHNOLGIES
 AUGER DRILLING
 PERCUSSION DRILLING
 JET DRILLING AND WASH DRILLING
 HIGH SPEED ROTARY DRILLING
DRILLING TECHNOLOGIES
AUGER DRILLING
 TYPES OF AUGERS
 POST HOLE AUGER
AUGER DRILLING
TYPES OF AUGER
 HELICAL AUGER
HOLLOW HELICAL AUGER
AUGER DRILLING
 The augers can be rotated and pushed into the ground manually
and by using motorized system.
 Using manually operated augers, bore holes of 100 mm diameter
and depth upto 20 m depending upon the type of soils.
 The auger drilling is effective in soils that possess some
stickiness.
 The soils which do not possess stickiness e.g. sands, augers are
not able to create a hole.
 AUGER BORING IS THUS MOST EFFECTIVE IN CLAYS, SILTY
CLAYES, CLAYEY SILTS etc.
 HOLLOW STEM AUGERS are sometimes are used for NON
STICKY soils.
PERCUSSION DRILLING
 ROPE HUNG BAILERS are
dropped from a certain height
to create hole in the soil and
filling it with some soils from
its bottom end.
 It can be used manually as
well as by machine operated
depending upon the depth of
exploration.
JET AND WASH DRILLING
 A bore hole is advanced into the soil using a high pressure water
jet to cut the soil and flush the cuttings out of the hole.
 Because the water jet tends to disturb the soil below the bottom
of the hole, JET DRILLING IS NOT USED where undisturbed
sample is required.
 In wash drilling, the soil is cut by UP/ DOWN action of chopping
bit, ROTARY action of bit, ROTARY ACTION ON CUTTING
PIPE.
 When undisturbed sample are required, rotary boring is preferred
since they do not disturb soil below the bottom of the hole as
much as the up/down action of chopping bit.
HIGH SPEED ROTARY DRILLING
 For drilling in ROCK, the preceding techniques do not work and
we have to resort to high speed drilling in which a core cutter with
its leading end fitted with diamond drill bit is simultaneously
rotated and pressed down.
 When the core cutter fills up, it is lifted to the ground surface and
the rock core is carefully removed.
 During the drilling process, drilling fluid circulates around the bit
to reduce the temperature produced due to drilling and to take
out slurry of rock dust from the bottom.