Lateral response of piles in weak calcareous sandstone

Abstract

Existing design methods for laterally loaded piles in soft rock have insufficient supporting case history data and consequently cannot be regarded as having a high level of reliability. This paper addresses the shortage of experimental data by describing the results from four instrumented lateral load tests on drilled and grouted piles installed in weak calcareous sandstone. The derived lateral load transfer (p-y) curves are first compared with existing approaches for weak rock and cemented soils. The paper then examines the potential of using cone penetration test (CPT) data directly for the design analysis of laterally loaded piles in weak rock. It is shown that equivalent elastic moduli of the rock controlling values of qc at the test site are very similar to those controlling lateral pile response. This finding is used to formulate a simple bilinear p-y approximation of the lateral response that requires qc data and an estimate of the rock’s effective stress strength parameters. It is shown that such an approach is likely to be sufficient for many practical purposes if the moment capacity of the pile section is incorporated in the analysis.