The uncased cast-in-situ piles can be used only in the condition, where ___

Under-reamed pile foundation is most suitable for _______ type of condition.

The art of driving piles into the ground was first established by ______

The allowable load which the pile can carry safely is determined on the basis of ____

The dimension of the bulb in an under-reamed pile can be checked by ______

When a pile hammer hits the pile, the total driving energy is equal to _____

The bearing capacity of a single pile in clay is mainly due to _____

The diameter of the under-reamed pile is kept equal to ___ times the diameter of pile steam.