Settlement of axially loaded piles entirely embedded in rock - analytical and experimental study

Abstract

Finite element analysis was performed to study the settlement behaviour of axially loaded piles entirely embedded in nonhomogenous rock. The elastic modulus of the rock mass was taken to increase linearly along the pile length starting from a nonzero value at the ground surface. Cases of pile-rock stiffness ratios that have not been considered in the literature were investigated. Such ratios are typical for reinforced concrete piles bored in sedimentary rocks. Results of the numerical analysis were verified through conducting static loading tests on full-scale piles in rock of well-defined physical and mechanical properties. Charts were developed to predict the elastic settlement of piles in rock. An equation was also introduced to incorporate the effect of rock nonhomogeneity in estimating the depth at which settlement becomes insensitive to the increase of pile length. A complementary numerical analysis utilizing a simple piled foundation system showed that the pile load share is sensitive to the rate of increase in rock stiffness along the pile length. The sensitivity is more pronounced for piled foundations resting on rock with high mass stiffness.