A Method for Predicting Base Resistance of Drilled Shafts in Disturbed Rock Mass

Conventional methods for estimating the base resistance of rock-socketed drilled shafts simply use the unconfined compressive strength of intact rock, although the base resistance also depends on in-situ rock mass characteristics. In this study, an improved method for determining the base resistance of drilled shafts socketed in disturbed rock masses is presented. The method is based on a finite element limit analysis with the Hoek-Brown (HB) failure criterion that is applicable to both the intact and jointed rocks. The method also emphasizes the importance of disturbance and unit weight of the rock mass. A database of base resistance from load tests with available rock properties are compiled from the literature, which is used for method validation. Comparison to the measured rock-socket base resistance indicates that the proposed method produces satisfactory predictions.