Ultimate bearing capacity of strip footing resting on rock mass using adaptive finite element method

Abstract

An essential requirement during the design of structures is a rational assessment of the ultimate bearing capacity of the footing resting on rock mass (q_u). The q_u is influenced by several parameters, and the simultaneous consideration of all such factors during the assessment of ultimate bearing capacity is a cumbersome process. Considering that the available literature lacks in providing the influence of various parameters of the rock mass on q_u, an attempt has been made in this study to evaluate q_u of a strip footing resting on a rock mass, which was presumed to follow the latest form of Hoek-Brown failure criterion using finite element modeling. The results obtained in this study were validated with the previous findings of the bearing capacity factors (N_σ0) for a footing resting on weightless rock mass. A comprehensive study has been performed to get an insight into the factors affecting the q_u of a footing resting over the rock mass by varying the Geological Strength Index (GSI) ranging from 10 to 100, as well as the disturbance factor (D) at 0 and 1, together with the embedment depth of the footing (D_f). The q_u is determined by the load-settlement response obtained from numerical simulations and the observed potential failure planes from the simulations are analyzed and discussed. The results showed that the q_u was greatly influenced by the GSI of the rock mass and the effect of D reduces with higher values of GSI. The study recommends that the q_u of a poor mass can be increased by placing the footing at a deeper depth (D_f).