Effect of soil variability on bearing capacity accounting for non-stationary characteristics of undrained shear strength

The objective of this paper is to investigate the bearing capacity of spatially varying soil in the presence of non-stationary feature of undrained shear strength. Firstly, undrained shear strength is modeled by a non-stationary random field. In this model, the mean of undrained shear strength is non-zero at the ground surface and linearly increases with depth, while the coefficient of variation (COV) of undrained shear strength keeps constant. Based on this non-stationarity, an algorithm is proposed to produce the corresponding random field. Then, Monte Carlo Simulations are carried out to evaluate the statistical characteristics of the resulted bearing capacity, followed by a detailed discussion on the effects of COV, strength gradient parameter, distribution type, and vertical auto-correlation length. At last, two computation schemes that enable the prediction of statistical characteristics (e.g., mean, standard deviation, and cumulative probability function) of bearing capacity in non-stationary random fields utilizing results from a stationary one are proposed, and demonstrated through numerical examples.