Masafumi Hirata

Numerical Simulation of Soil Structures Reinforced by Geosynthetics

The behavior of soil structure reinforced by geosynthetics is governed by the mechanical interaction of soils and geosynthetics materials. In a numeric simulation of such soil structure behavior, appropriate modeling of the mechanical interaction is required. In this chapter, the numerical modeling of the geosynthetics-reinforcement mechanism in soil structures is described. The confining effect brought about by geosynthetics working so as to prevent dilation of soils is considered using elasto-plastic constitutive models that can express dilation of soils with shear. The deformation–failure behavior of two full-scale, geosynthetics-reinforced soil structures were simulated using the finite element computation technique. The compacted materials actually used were sands, but herein the compacted soils are treated as if they are clays saturated and heavily overconsolidated; and a determination procedure for input parameters needed in these models is proposed. Last, numerically predicted and monitored behavior are compared.

Spatial Discretization of a Water Head in Soil–Water Coupled Finite Element Method Analysis Using the Hybrid-Type Penalty Method

In the present soil–water coupled finite element method (FEM) analysis, a program known as deformation analysis considering stress anisotropy and reorientation (DACSAR; Iizuka and Ohta, Soil Found 27(3): 71–87, 1987), the spatial discretization procedure for representing the water head at the center of each finite element was adopted. However, it is known that the outflow of pore water from the element boundary happens to be incorrectly calculated depending on the mesh arrangement and the inclination of the boundary. To address this problem, this chapter proposes a more rigorous spatial discretization procedure for pore water flow. Namely, the hybrid-type penalty method (HPM) is introduced to spatially discretize the pore water flow in soil–water coupled finite element formulation, and the DACSAR program is modified using the proposed technique.