a brief of soil mechanics with various IS code

1. Presented by
Er.Krishan Dev
(Arkitechno India Pvt. LTD.)
Presented to
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2. I. Soil Mechanics
II. Soil
III. Soil Classification
IV. Physical Properties
V. Hydraulic Properties
VI. Mechanical Properties
VII. Application of Soil Mechanics
VIII. Liquefaction
IX. Expansive Soil
X. Soil Stabilisation
XI. Major soil deposits in India
XII. Conclusion
XIII. Reference Books
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3.  Discipline of Civil Engineering, involves study of soil, its behaviour
and application as an engineering material.
 Involves the law of mechanics and hydraulics to soil engineering
problems.
• Mechanical law : SBC, Settlement, strength.
• Hydraulics law : Seepage, Well, Permeability.
 Father of Soil Mechanics: Karl Von Tarzaghi.
• Term Soil Mechanics is coined by him in 1925.
 Grandfather of soil mechanics : Coulomb (1776).
• Shear strength is combination of cohesion and angle of internal
friction.
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4.  Generated by weathering of Rocks and Geological cycle.
Mechanical weathering Chemical weathering
•Soil contains original composition
of the parent rock.
•Composition of soil has been
altered by chemical reactions.
•Mainly Cohesionless soil. •Mainly Cohesive soil
•Forcing agents: Forcing agents:
• Wind • Temperature
change
•Oxidation •Leaching by
water
• Animal • Ice •Hydration •Leaching by
organic acids
• Water • Plants •Carbonation 4

5.  Different meaning to different fields.
• Padologist : Substance support plant life.
• Geologist : Substance cover earth surface.
• Engineer : material can be used for
 Built on : foundation of structures.
 Built in : Tunnel, basements.
 Built with : Embankments, Roads, Dam.
 Support : Retaining wall.
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6.  Weathering
• Residual
• Transported
 Alluvial
 Marine Water Transported.
 Lacustrine
 Glacial Drift - Glaciers
 Aeoline - Wind Blown
 Colluvial - Gravity
 Particle size and Texture.
• Coarse or fine grained
 Density and void ratio.
• Loose or Dense
 Swelling Index.
• Expansive or Non expansive
 Highway Research Board.
• Good or Inferior
 USCS System
• Coarse or fine grained (well or poorly graded, plasticity level) 6

7.  Combination of Air, Water (Voids) and solids.
 Variation of these three provide uniqueness to soil.
 Heterogeneous.
 Not behave linearly.
 Therefore to understand the behaviour of soil we have to
understand its Properties.
• Physical Properties .
• Mechanical Properties.
• Hydraulic Properties.
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8. Name of properties Method of determination IS Code
UsedLab. Field
Water content =
Wt. Of water/Wt. Of solids
•Oven Drying
•Pycnometer
•Sand bath
•Alcohol
•Calcium
Carbide
I.S 2720
(5)
I.S 2720
(2)
Specific Gravity =
Unit wt. Of soil solids/unit
wt. Of water
•Pycnometer
•Density Bottle
I.S 2720 (3)
Particle Size Distribution •Sieve Analysis
a. Coarse sieve
b. Fine Sieve
•Sedimentation analysis
a. Pipette method
b. Hydrometer method
I.S 2720 (4)
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9. Name of properties Method of determination IS Code
UsedLab. Field
Bulk Density =
Mass of soil/Vol. Of soil
•Water
displacement
•Rubber balloon
•Submerged
mass density
•Sand
replacement
•Core cutter
IS 2720
(33)
I.S 2720 (28)
I.S 2720 (29)
Dry density =
Dry mass of soil solids/ Total
vol. of soil
•By relationship of bulk density
and water content
IS 2720 (7,8 and 9)
Void ratio =
Vol. Of voids/ Vol. Of solids
•By relationship of dry density IS 2720 (7 and 8)
Liquid Limit = soil is in
liquid but having small
shearing strength.
•Casagrande
•Static cone penetration
I.S 2720 (5)
Plastic Limit = soil starts
crumble at a dia. Of 3 mm.
•Thread method I.S 2720 (5)
Shrinkage Limit = decrease
in water not lead to vol.
Change.
•Shrinkage limit apparatus I.S 2720 (6)
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10. Name of properties Method of determination IS Code
UsedLab. Field
Permeability = Permits the
passage of fluid
•Constant head
•Falling head
•Consolidation
•Pumping in
•Pumping out
IS 2720
(17)
IS 5529
(1)
Specific yield =
Vol. Of water drained by
gravity/ Total vol.
• By Grain size
Specific Retention =
Vol. Of water retained by
gravity/ Total vol.
•By Grain size
Seepage pressure =
pressure exert by water on
soil
•Flow net
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11. Name of properties Method of determination IS Code
Used
Lab. Field
Shear Strength •Triaxial
•Direct shear
•UCS
•Vane shear
•SPT
•CPT
IS 2720 (11)
IS 2720 (13)
IS 2720 (10)
IS 4434
IS 2131
IS 4968
Settlement =
decrease in volume.
•Consolidation
•Compaction
•Proctor needle
•Plate load
IS 2720 (15)
IS 2720 (7
& 8)
-
IS
1888,921
4
Slope Stability = Inclined
soil structure
•Shear strength and Shear stress
•Swedish slip circle
•Taylor stability no.
Lateral Earth Pressure =
Transverse Pressure
Exerted by soil.
•Cohesion and Angle of internal
friction,
•Rehbann, Culmann, Rankine 11

12. Name of properties Method of determination IS Code
Used
Lab. Field
Safe Allowable Bearing
Capacity =
Should fulfil bearing and
settlement Criteria
•Shallow:
•Cohesion and
Angle of internal
friction
•Pile:
•Dynamic
Formula
•Static Formula
•Plate Load
•SPT
•SCPT
•Pile Load
•Cone
Penetration
IS 6403
IS 8009
IS 2950
(1)
IS 2911
(1,2,3)
IS 1888
IS 2131
IS 4968
(3)
IS 2911
(4)
IS 4968
(3)
Stress Distribution =
Mobilisation of stress
under a footing.
•Soil Type
•Boussinesq
•Westergaard
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13. Shallow
Footings
Strip Spread Combined
Rafts
1.1Foundation Design : Transfer super structure load to soil.
 Design : Allowable Bearing Capacity.
D/B ≤1
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14. Deep
Pile
Load (End
and Friction)
Material
(Timber, Steel,
Concrete)
Function
(Tension,
Compressio
n)
Casting (Pre
and In-situ)
Pier
Drilled
Excavated
Caissons
Box
Open
Pneumatic
D/B ≥1
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15. Ground water table.
Soil Type.
Stress distribution.
Vibration.
Load.
Expansiveness.
Scour.
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16. 1.2 Pavement Design : Rigid or Flexible both transfer load
to soil subgrade.
 Design : Allowable Bearing Capacity Bearing Capacity,
Penetration.
 Keep in Mind :
Load Repetition.
Fatigue.
Frost.
Heave.
Thaw.
Swell and Shrinkage.
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17. 1.3 Underground and Earth Retaining structure:
o Underground : Tunnel. Basements, Pipe, Conduits.
o Retaining : Retaining Wall, Cofferdam.
o Design : Lateral Earth pressure.
o Keep in mind :
Soil structure Behaviour.
Initial standing time.
Initial standing height.
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18. 1.4 Embankment and Excavation : Slope tries to move
downwards because of gravity, undercutting, seepage etc.
 Design : Slope Stability.
 Keep in mind :
Height of slope.
Resisting Force.
Driving Force.
Shear strength.
FOS
Seepage.
Earthquake. 18

19. 1.5 Earth Dams : Restrict the flow of water
 Design : Seepage analysis, slope stability, consolidation, Allowable
Bearing capacity.
 Keep in mind :
OMC and Dry density.
Plasticity characteristics.
Permeability.
Specific Gravity.
Particle size distribution.
Flow Net.
Gradation of soil. Hoover Dam on Colorado river
Earthquake. (U.S. State of Nevada & Arizona)
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20.  Liquefaction : Key for fixing foundation depth in saturated loose
sand and seismic zone.
 Soil looses its all shear strength and behave as a liquid.
 Reason : High strain lead to un drained condition.
 Pore water pressure increases and effective stress decreases.
Niigata EQ (1964)
 Key note :
• EQ induced Shear stress < Shear strength of soil.
• Can occur only if saturated sand is at shallower Depth < 12m.
• Can occur only if SPT N value is less then twice of depth. 20

21.  High potential to volume change.
 Reason :
• Clay mineral (Montmorillonite).
• Osmosis.
• Hydrated cation.
 Methods to Measure :
• Differential free swell test.
• Cole
• Clay content
• CEC and Ac
 Prevention :
• Under ream Pile , Electro kinematics, Chemical stabilisation.
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22. Mitchel 1972 22

23. Name of soil Places where it is found
Black Cotton Maharashtra, Gujarat, Madhya
Pradesh, Andhra Pradesh, Tamil
Nadu, Karnataka.
Marine soil Coast Line, Rann of Kutch.
Desert soil Rajasthan
Alluvial soil Indo-Gangetic plain, North of
Vindhyanchal
Laterite Kerala, Odisha, Karnataka, West
Bengal, South Maharashtra.
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24.  Any structure which depends upon soil in any manner needs
the crystal knowledge of soil mechanics.
 Soil mechanics provides tools to understand the behaviour of
soil.
 Soil mechanics is base of foundation engineering as well as
other design.
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25. MUNI BUDHU B.C. PUNMIA C. VENKATRAMAIAH
BRAJA M. DAS JOSEPH E.
BOWELS
SWAMI SARAN
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26. THANK YOU
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