THE AXIAL CAPACITY OF PILE SOCKETS IN ROCKS AND HARD SOILS

In this paper, the traditional approaches to design of piles in soil and rock are briefly reviewed. It is shown that the unrelated empirical relationships developed for soil and rock lead to considerable uncertainty in the design of piles in the large class of hard soil or soft rock that are sometimes referred to as intermediate materials. A new method for predicting the shaft resistance of piles socketed into rock, and based on fundamental principles is outlined. It is shown that the shaft resistance predictions of this method agree well with the field test data for rock and hard soil, and suggest a transition which links the disparate empirical relationships for soil and rock. It is demonstrated by way of a limited parametric study that shaft roughness and socket diameter are critical factors in the performance of piles constructed in these materials. (A)