Undrained bearing capacity of spatially random clays by finite elements and limit analysis

This paper combines the random field methodology with the upper and lower bound finite element limit analysis algorithms (Sloan 1988, 1989) to study the bearing capacity of undrained clays with spatially varying shear strength. The results of the Random Field Limit Analysis (RFLA) analyses are compared with existing results obtained by elastic-plastic Random Finite Element (RFEM) analyses (Griffiths and Fenton 2001). It is shown that RFEM results are bounded by RFLA ones. The difference (Nd) between the upper (Nu) and lower (Nl) bound bearing capacities in random soils is shown to be a lognormally distributed random variable. The effects of spatial correlation length and coefficient of variation of undrained strength on Nu and Nl are also studied.