Correct Answer - Option 4 : None of the above
Shear strength of soil is the capacity of soil to resist shearing stresses. It can be defined as the maximum value of shear stress that can be mobilized within a soil mass. If this value exceeded by the shear stress on any plane or a surface at a point, failure will occur in soil because of movement of a portion of the soil mass along that particular plane. The soil is then said to be fail in shear. Therefore, shear strength generally represented the strength of soil.
As per Mohr- Coulomb criteria, Shear strength of soil is given as:
τ = C + σ tanϕ
C is the Cohesion
σ is normal stress
ϕ is the friction angle
From above, it can be concluded that
a. It increases with an increase in the normal stress.
b. It is proportional to the cohesion of the soil i.e. increases with increase in cohesion.
c. it increases with increases in friction angle.