A New Approach to Estimate Side Resistance of Rock Socketed Drilled Shafts

The uniaxial compressive strength of intact rock is widely used as the sole factor to estimate the side resistance of drilled shafts socketed in rock. However, the side resistance should also depend on in situ rock mass characteristics such as rock type, strength, joint frequency, and weathering conditions. In this study, a new approach is proposed to estimate the side resistance of rock socketed drilled shafts. The approach is based on the GSI rock mass classification, and the Hoek and Brown failure criterion. Inclusion of all these factors into the proposed method explains, to some extent, the differences that are obtained when various empirical methods are used. Comparisons between observed side resistances from field case studies and estimated side resistances with the proposed method show a good correlation. The method appears to be robust since the results are relatively insensitive to estimation from the different rock mass classification and properties and are comparable with predictions from previous empirical correlations.