**31) What is the intensity of pressure below a point load where r is equal to zero on the axis of loading?**

a) σ_z= (0.4775Q )/(z^2 )

b) σ_z= (0.7Q )/(z^2 )

c) σ_z= (0.4775Q )/( z^3 )

d) σ_z= (0.8Q )/z

Komal Bhandakkar Answered question January 5, 2021

**Answer: a) σ_z= (0.4775Q )/(z^2 )**

Explanation:The formula of Boussinesq’s vertical stress is,

σ_z= 3Q/(2π z^2 ) 〖{1/(1+〖(r/z)〗^2 )}〗^(5/2)Put, r is equal to zero.

We will get,

σ_z= (0.4775Q )/(z^2 )

Komal Bhandakkar Edited answer January 5, 2021