Analysis of Laterally Loaded Shafts in Rock

Abstract

The behavior of both flexible and rigid shafts socketed into rock and subjected to lateral loads and moments is studied. Parametric solutions for the load‐displacement relations are generated using the finite element technique. Based on these solutions, simple, approximate, closed‐form equations are developed to describe the response for the full range of loading conditions, material parameters, and socket‐rock mass stiffnesses encountered in practice. These results are in close agreement with available solutions for the limiting cases of flexible and rigid shafts. The solutions give horizontal groundline displacements and rotations and can incorporate an overlying soil layer. The problem of assessing the lateral load capacity of rock‐socketed foundations is also addressed, and a method of analysis to predict this capacity is suggested. The application of the theory, in the form of back‐analysis, to a single case involving the field loading of a pair of rock‐socketed shafts is also described.