Question

: To design and construct a retaining wall, the Engineer extracted an undisturbed cohesionless soil sample from the construction site. Why the engineer collected the undisturbed soil sample? Also discuss how the height of the soil retained and properties of cohesionless soil retained influences the calculation of lateral pressure of soil.

Answer 1

These kinds of samples are used for testing the properties in laboratory, without disturbing its structure, texture, density, natural water content and stress condition are help in computing the compressibility, shear strength, and permeability of the soil.

We know that lateral pressure is given as

p = 0.5* (coefficient of earth pressure)* unit weight of soil * height of soil^2

Pressure is directly proportional to square of height of soil/wall.

Coefficient of pressure is dependent on phi values.

Ka= {1-sin(phi))}/{1+sin(phi)}

Ka*Kp=1