civil engineering

1. TYPES OF SOIL,SHEAR STRENGTH
OF SANDS: STRESS STRAIN AND
VOLUME CHANGE BEHAVIOUR,
ANGLE OF REPOSE
SUBMITTED BY :
RAHULCHHATA(CO20236)
RAHUL YADAV (CO20237)

2. COHESIVE SOIL
• fine grained , low strength and easily
deformable soil that have a tendency
to adhere. Example- clay, silt
• Clay have cohesion between
particles.
• Silt have both cohesion and frictional
resistance.
COHESIONLESS SOIL
• Any free running type of soil ,whose
strength depends on friction between
particles . Example – sand , gravel
• Dense sand have interlocking and
frictional resistance
• Loose sand have only frictional
resistance.
TYPES OF SOIL

3. STRESS STRAIN CHARACTERISTICS OF SAND
• Stress strain curve is plotted between deviator stress and axial
stress.
• In dense sand the peak stress is attain at a low strain and
decreases with increasing strain and finally the stress becomes
constant called the ultimate stress. The peak stress obtained is
used to define the shear strength.
• In loose sand the stress increases gradually with strain and
finally reaches to ultimate stress, no peak value is obtained. So,
maximum stress value or arbitrary selected value is used to
define shear strength.

4. VOLUME CHANGE CHARACTERISTICS OF SAND
• The curve is plotted between volume change and axial strain.
• In dense sand while increasing axial strain initially volume
decreases, but after the interlocking between the particles
breaks the volume gradually increases.
• In loose sand volume decreases continuously with increasing
axial strain.

5. VOID RATIO CHARACTERISTICS OF SAND
• Critical void ratio(ecr ) – At large value of shearing strain the void ratio
of both initially loose and initially dense sands approaches a constant
void ratio , further application of shearing strain does not produce
change in void ratio or volume called the critical void ratio.
• In loose sand (e > ecr )
• In dense sand (e< ecr )
• In loose sand on increasing shear strain the void ratio decreases from
an initial large value el
• In dense sand the initial void ratio ed increases after slight initial slight
decrease.

6. DETERMINATION OF CRITICAL VOID RATIO
• To determine the ecr different specimens of soil, each at a different initial void ratio, are sheared to
failure, after subjecting them to same cell pressure 𝜎3 in all cases. The corresponding volume
changes positive or negative are measured. These are plotted against the initial void ratio.
The void ratio corresponding to zero volume change is then the critical void ratio for that
particular confining pressure.

7. FACTORS AFFECTING ANGLE OF SHEARING
RESISTANCE
∅1= grain shape factor
∅2 = 𝑔𝑟𝑎𝑖𝑛 𝑠𝑖𝑧𝑒 𝑓𝑎𝑐𝑡𝑜𝑟
∅3= correction factor for gradation
∅4 = 𝑐𝑜𝑟𝑟𝑒𝑐𝑡𝑖𝑜𝑛 𝑓𝑎𝑐𝑡𝑜𝑟 𝑓𝑜𝑟 𝑟𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦

8. ANGLE OF REPOSE
• The maximum slope at which a material , drop down
through a natural process remains stable, is called the angle
of repose.
• The use of angle of repose is limited only to dry , granular
soils because of the constant value of angle of repose.
• The angle of repose is equal to the angle of internal friction
of soil in its loosest state .

9. THANK
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