Effect of spatial variability on the bearing capacity of cement-treated ground

This paper presents a reliability assessment for the undrained bearing capacity of a surface strip foundation based on the results of a probabilistic study in which the shear strength and unit weight of cement-treated ground are represented as random fields in Monte Carlo simulations of undrained stability using numerical limit analyses. The results show how the bearing capacity is related to the coefficient of variation and correlation length scale in both shear strength and unit weight. Based on the results, the authors propose an overdesign factor, tolerable percentage of defective core specimens, and resistance factors for LRFD ultimate limit state of surface footings on cement-treated ground in order to achieve a target reliability index and probability of failure. The proposed method is illustrated through example calculations based on the spatial variation of unconfined compressive strength measured using a variety of cement-mixing methods from projects in Japan.