Piles in rock: Socket resistance estimation using JRC and fractal dimension

Socket resistance contributes significantly to pile capacity. In the present work, an approach is presented for estimating the capacity of side-resistance-only piles socketed in rock by considering the effect of interlocking in terms of JRC and Fractal Dimension. Unlike available methods of quantification of roughness of surfaces, Fractal geometry allows the description of irregular shapes. A correlation is established between JRC and Fractal Dimension (D). This is used to estimate socket contribution and predict pile capacity based on an iterative procedure. Here the axial load is calculated by incrementing vertical displacement along the interface and estimating the shear strength mobilised at the interface using above correlation. Pile socket data reported in literature is used for validating the approach. The study is then extended to piles socketed in weathered rock in Mumbai region. The results show that it is feasible to make a reliable estimate of the socket strength contribution