Question

In the pile load estimation in very soft clay, the adhesion factor considered is ............

• A. 1.0
• B. 0.7
• C. 0.3
• D. zero

Hint:

For very soft clays, assume full adhesion between pile and soil. Use \( \alpha = 1.0 \) for estimating skin friction in pile capacity calculations.

Answer 1

The Correct Option is A

In pile load estimation, particularly in cohesive soils like clay, the adhesion factor (\( \alpha \)) is used to estimate the skin friction resistance offered by the clay along the surface of the pile.
In the case of very soft clay, the skin resistance is assumed to be entirely mobilized and proportional to the undrained shear strength. The adhesion factor (\( \alpha \)) approaches unity (1.0) in such cases, because the bond between the pile surface and the soft clay is maximized due to full adhesion.
The skin friction is estimated using the formula: \[ f_s = \alpha \cdot c_u \] where \( c_u \) is the undrained cohesion of the clay. For very soft clay, \( \alpha = 1.0 \), indicating complete adhesion. Thus, the correct answer is: \[ \boxed{1.0} \]