Effect of element sizes in random field finite element simulations of soil shear strength

In random field finite element analysis (FEA), continuous random fields must be discretized, and the discretized solution is different from the continuous one. In this paper, it is found that the tolerable maximum element size to achieve acceptable accuracy for soil shear strength is surprisingly small. The discrepancy is governed by the line averaging effect along potential slip curves – the discrepancy is small if the line averaging is strong. Discretization based on element-level averaging (ELA) is always unconservative, giving mobilized shear strength always larger than the actual value, while discretization based on the midpoint method can be sometimes conservative.

► Mobilized shear strengths of spatially variable soils are simulated by finite element analysis (FEA).
► Maximum element size retaining correct mobilized strength is identified for two FEA discretization methods.
► Degree of discrepancy in resulting mobilized strengths is determined if element size in #2 is exceeded.
► The mechanisms causing the discrepancy in #3 are discussed for two FEA discretization methods.