International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 2, Issue 12, December 2012)
Performance, Problems and Remedial Measures for the
Structures Constructed on Expansive Soil in Malwa Region,
India
Kartikey Tiwari1, Sahil Khandelwal2, Aman Jatale3
1
Department of Civil Engineering, Sanghvi Institute of Management & Science Behind IIM-Indore, Pigdambar, 453331,
Indore, India
2
Department of Civil Engineering, Sanghvi Institute of Management & Science Behind IIM-Indore, Pigdambar, 453331,
Indore, India
3
Department of Civil Engineering, Sanghvi Institute of Management & Science Behind IIM-Indore, Pigdambar, 453331,
Indore, India
In Malwa region, India previously it seems that only
Black Cotton Soil up to greater depth. However, during
construction of Indore By-pass ( Presently RAUMANGLIYA BY-PASS ) project, it was observed that
Montmorillionite (60-70 %), Illite (5-10 %), Kaolinite (510%) is present.
Essentially expansive soil is one that changes in
volume in relation to changes in water content,
Expansive soils are found in humid environments where
expansive problems occur with soils of high Plasticity
Index (Ip) or in Malwa soils where soils of even
moderate expansiveness causes significant damage.
Expansive
soils
contain
minerals
such
as
Montmorillionite, Illite, Kaolinite clays that are capable
of absorbing water. When they absorb water they
increase in volume, The more water they absorb the more
their volume increases. This change in volume can exert
enough force on a structure to cause damage. These
volume changes are either in the form of swell or in the
form shrinkage and this is why they are sometime known
as swell/shrink soils.
Shrink-swell soils which expand due to high ground
moisture experience a loss of soil strength or “capacity”
and the resulting instability results in various forms of
Sub-grade problems and slope failure.
Expansive soils will also shrink when they dry out.
This shrinkage removes support from structures and
result in damaging subsidence. Fissures in the soil also
develop. These fissures facilitate the deep penetration of
water when moist conditions or runoff occurs. This
produces a cycle of shrinkage and swelling that places
repetitive stress on structure.
When expansive soils are present they will generally
not cause a problem if their water content remains
constant. The situation where greatest damage occurs is
when there are significant or repeated moisture content
changes.
Abstract— The Present paper deals with the properties of
expansive soil in Indore (Malwa region), Madhya Pradesh,
India. The expansive soil here especially posses a problem to
many Structures and National Highways constructed which
is caused due to presence of mineral Montmorillionite. This
paper presents the case study about the Performance,
Problems, and Remedial measures for the Structures
Constructed on expansive Soil. The swelling characteristics
of expansive soil and its effects on the structures are being
revealed.
Expansive soil popularly known as Black Cotton Soil
presents a very challenging task for construction work in
Malwa region. The effect of adding Gypsum, Crude oil and
Laying CNS (Cohesive Non-swelling) layer on expansive soil
is studied. In areas with very less probability of seismic
activities, vibratory ground improvement can reduce the
potential for liquefaction and ground deformation due to
lateral spreading. Various tests are performed on the
expansive soil to determine its Swelling Pressure test, Triaxial Compression Test, Optimum Moisture Content,
Conducting Field Density, Liquid Limit, Plastic Limit,
Shrinkage Limit, Specific Gravity etc.
The experimental results of this paper seeks to explore
and explain the phenomena causing swelling and the
attendant damage based on a local setting, and on the basis
of this study various multiple remedial measures are given
to overcome the swelling of expansive soils by different
means and it is found that swelling pressure decreases with
increase in bearing capacity of soil by addition of Gypsum,
Crude oil, Laying CNS layer and use of Under-reamed piles
(single bulb) under economical consideration.
Keywords: CNS layer, Crude oil, Expansive Soil, Gypsum,
Swelling characteristics, Under-reamed piles.
I. INTRODUCTION
Large scale distress, due to expansive shrinking nature
of expansive soil, can be prevented by either obstructing
the soil movement and reducing the swelling pressure of
soil or making the structure sufficiently resistant to
damage from soil movement.
626
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 2, Issue 12, December 2012)
Soils are composed of a variety of materials, most of
which do not expand in the presence of moisture.
However, a number of clay minerals are expansive.
These include: montmorillionite. There are also some
sulphate salts that will expand with changes in
temperature. When a soil contains a large amount of
expansive minerals it has the potential of significant
expansion. When the soil contains very little expansive
minerals it has little expansive potential.
The structures commonly affected by expansive soil
are residential structures, roads, irrigation canals &
spillways. This report deals exclusively with variations of
Swelling Pressure, Tri-axial Compression Test, Optimum
Moisture Content, Conducting Field Density, Liquid
Limit , Plastic Limit, Shrinkage Limit, Specific Gravity
etc. through expansive soil in context of slab-on-grade
performance in Malwa region, India.
Fig.2. Cracks develop at Indore-bypass
III. RESULT
A. Experiments Performed
1. Specific Gravity
2. Soil Classification
3. Liquid Limit
4. Plastic Limit
5. Plasticity Index
6. Shrinkage Limit
7. Optimum Moisture Content
8. Conducting Field Density
II. PROBLEMS FOR THE STRUCTURES CONSTRUCTED ON
EXPANSIVE SOIL
The problem is more in case of light structures; those
cannot counteract the upward thrust posed by expansive
soils. The damage will be apparent, usually, several years
after construction. The soil below will exert swelling
pressure both upwards and laterally. As a result, the Subgrade of road & floor slab is lifted up, leading to cracking
roads & floor. Cracking is normally evident at the
Surface texture of roads & corners of window and door
openings.
Fig 1.Cracks in interior walls, as a result of upward soil pressure
The ensuing leakage further aggravates the situation.
Roads that pass through expansive soil sub-grade are
subjected to heaving and shrinkage settlement of these
treacherous soils. Both the lined and unlined canals are
subjected to the vagaries of expansive soils. The unlined
canal slopes erode and become soft. Canal beds heave up
obstructing the functioning of the canal. The concrete
linings splinter like glass pieces on account of deleterious
cyclic movement of background swelling clay. This
heavy results in seepage losses.
Fig. 3. Requirement for performing Liquid Limit Test.
627
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 2, Issue 12, December 2012)
Fig. 6. Soil sample after performing test.
Fig. 4. Soil sample filled in bowl of cassegrande Apparatus.
Fig. 7. Requirement for performing Plastic Limit Test
Fig. 5. Cut made in soil sample
628
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 2, Issue 12, December 2012)
Fig. 9. Graph Between Plastic Index and liquid Properties
IV. SUGGESTED REMEDIAL MEASURES FOR EXPANSIVE
SOIL
A. Providing Foundation surrounded with Granular
Fill:1. Excavation carried out upto depth greater than
the depth of foundation by about 20-30 cm.
2. Free drainage material such as mixture of sand
& gravel is filled & compacted upto the bottom
level of foundation.
3. R.C.C footing foundation is constructed at this
level, over which the brick wall may be raised.
4. A R.C.C apron with light reinforcement and of
about 2m width is provided all along the
building to prevent the moisture from directly
entering the foundation.
5. The cushion of granular soil below the
foundation will absorb the effect of swelling,
thereby reducing its detrimental effects on
R.C.C foundation.
6. Provide slotted footing so that this may reduce
the swelling pressure.
7. Construction should be done in dry season when
soil shrinks to its threshold level.
Fig. 8 Ellipsoidal soil mass during test.
TABLE I
RESULTS OF EXPERIMENTS
Sr.No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Particulars
Specific Gravity
IS Soil Classification
Liquid Limit (WL)
Plastic Limit (WP)
Plasticity Index (IP)
Shrinkage Limit (WS)
Optimum Moisture Content
(%)
Conducting Field Density
(KN/M3)
Degree of expansion
Observations
2.65
MH-OH
58.73 %
32.18
26.55
17.19
18.63 %
16.89 %
Very High
629
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 2, Issue 12, December 2012)
TABLE II
FOR THICKNESS OF CNS LAYER FOR SLOPING & LINING
OVER EXPANSIVE SOIL
Swelling Pressure of Soil
in KN/M2
50 – 150
200 – 300
350 – 500
Thickness of CNS
Material in cm.
75 – 85
90 – 100
105 – 125
C. Using of Under-reamed Piles to Carry Load up to
Stable Zone:Fig. 10. Wall without Footing and Wall with Footing and Void
Ratio
1.
2.
3.
Under-reamed piles with single under-ream are
vastly used in expansive soil to construct the
safe foundation.
The bulb or the under-ream of such a single
reamed pile is placed in the stable zone where,
there will be no change in moisture content.
The pile is extended into the stable zone by
sufficient depth as to take care of uplift pressure
exerted on pile shaft in the unstable zone.
Fig. 11. Typical Shallow Foundation in Expansive Soil
B. Using CNS layer technology:1. This method consists of laying a layer of
Cohesive-Non swelling soil (CNS), over the
expansive soil to a depth to counter react the
detrimental effect of having caused due to
Expansive soil.
2. The larger the thickness of CNS layer over the
expansive soil lesser the swelling and
Deformation.
3. Evidently the thickness of CNS layer is thicker
for more expansive soil & thinner for less
Expansive soil.
4. Some percentage of clay, sand and the existing
swelling soil may be used as CNS material.
Fig. 12. Schematic Diagram of Under-Reamed Pile (Single-bulb incast situ Pile)
D. Addition of Gypsum:1.
The use of CNS layer has found to be very effective in
construction of road pavement and also water resources
project particularly in Lining of Canals constructed in
expansive soil in Indore. The CNS layer is placed over &
before placing of side slopes for roads and lining of water
resource projects.
2.
630
Gypsum, in addition to prevention and
correction of sodicity, include greater stability
of soil organic matter, more stable soil
aggregates, improved water penetration into soil,
and more rapid seed emergence.
Gypsum can help break up compacted soil and
decrease penetrometers resistance. Combination
with organic amendments also helps, especially
in preventing return of the compaction.
International Journal of Emerging Technology and Advanced Engineering
Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 2, Issue 12, December 2012)
3.
4.
5.
Gypsum improves the ability of soil to drain and
not become waterlogged due to a combination
of high sodium, swelling clay, and excess water.
Soils that have been treated with gypsum have a
wider range of soil moisture levels where it is
safe to till without danger of compaction or deflocculation.
Gypsum can decrease the swelling and cracking
associated with high levels of sodium on the
montmorillionite type clays. As sodium is
replaced by calcium on these clays they swell
less and therefore do not easily clog the pore
spaces through which air, water and roots move.
To understand and hence engineer expansive soils in
an effective way it is necessary to Understand soil
properties, suction/water conditions, water content
variations
temporal
and
Spatial
and
the
geometry/stiffness of foundations and associated
structures. This paper Provides an overview of these
features and includes methods to investigate expansive
Behaviour both in the field and in the laboratory together
with associated empirical and Analytical tools to evaluate
expansive behaviour. Following this remedial measures
for pre and Post constructions are highlighted for both
foundations and pavements together with methods to
ameliorate potentially damaging expansive behaviour
Addition of gypsum will reduce the swelling pressure.
Limit the foundation depth if swelling soil is at some
depth so that distance between foundation and swelling
soil will be more and as the distance is more there are
less chances of cracks in building. Take effective
measures to maintain moisture equilibrium in foundation
soil, add Narmada sand in the existing swelling soil.
REFERENCES
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[2]
[3]
[4]
E. Crude Oil:1.
2.
It should be sprayed on top surface of the roads
as it helps in lubrication of surface layer with
the aggregates.
It should be preferred over water as its density is
much higher than that of water.
[5]
[6]
V. CONCLUSION
Expansive soils are one of the most significant ground
related hazards found in central region, Expansive soils
are found throughout and are commonly found in
arid/semi-arid regions where their high suctions and
potential for large water content changes on
exposure/deficient with water can cause significant
volume changes. In humid regions such as Indore
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clays of high IP. Either way, expansive soils have the
potential to demonstrate significant volume change in
direct response to changes in water content. This can be
induced through water ingress, through modification to
water conditions or via the action of external influence
such as trees.
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