Reliability-based design for allowable bearing capacity of footings on rock masses by considering angle of distortion

This study addresses the impact of spatial variability on the angle of distortion between two footings in rock masses. A simple elasto-perfectly-plastic model based on the Hoek–Brown criterion is taken to simulate the spatial variation of rock mass properties in the finite element analyses. This model is calibrated by a large rock mass database. With Monte Carlo simulations, stochastic samples of angle of distortion between two footings are obtained, which are further used to derive reliability-based allowable bearing stresses. The analysis results show that the geological strength index (GSI) of rock masses and uniaxial compressive strength of intact rock are the two dominate factors that affect the reliability-based design. Comparisons to the existing codes show that these codes are appropriate for poor to fair rock masses, conservative for good to very good rock masses and un-conservative for very poor rock masses.

► We compile a large database for deformation modulus of rock mass.
► We compile a database of uniaxial compression strength of intact rock.
► We propose a probabilistic model for the random fields of rock mass properties.
► Random field finite element is used to quantify distortion angle between two footings.
► Tables and charts are provided for reliability-based design.