Characterizing Lateral Soil-Structure Interaction of Drilled Shaft in Rock

Drilled shafts socket in rock have been used widely as a foundation system for highway bridges. The method of p-y curves has been considered as the most universally accepted method of analysis. In this paper, recent research at Ohio Department of Transportation, including both field lateral load tests on large-size drilled shafts in rock and theoretical study using 3-dimensional finite element (FE) simulation techniques, will be described. Using FE simulation results, coupled with field testing data, theoretical models for p-y curves in rock mass are derived. One case involves a rock mass where elastic rock properties could be treated as isotropic materials and the rock strength is governed by Hoek-Brown strength criteria. The second case involves a rock mass with dominant joint sets such that the elastic rock properties could be characterized as an equivalent transversely isotropic material while the strength of rock is governed by anisotropic strength criteria. The validity of the proposed p-y criteria is presented by way of comparisons between predicted shaft load-deflection and moment-depth curves and measured field data.