Question

A concentrated vertical laod of 6000 lbf is applied at the ground suface most nearly what is the increase in the vertical pressure 3.5 ft below the surface and 4 ft away from a point directly below the concentrated load?

(A) 29 lbf/ft^2
(B) 36 lbf/ft^2
(C) 41 lbf/ft^2
(D) 58 lbf/ft^2

Answer 1

the correct answer is option A

Step-by-step explanation:

given,

Load = 6000 lbf

depth = 3.5 ft

distance from the load = 4 ft

vertical stress =
`\frac{3Pz^3}{2\pi (r^2+z^2)^{(5)/(2)}}`

=
`\frac{3* 6000* 3.5^3}{2\pi (4^2+3.5^2)^{(5)/(2)}}`

= 28.96 lbf/ft²

= 29 lbf/ft²

hence, the correct answer is option A