Steady-State Groundwater in Mechanical Stabilized Earth Walls of Various Dimensions with Geocomposite Back Drain Installation

Abstract

Recently, considerable risks to the internal instability of mechanically stabilized earth (MSE) walls have been encountered from the inadequate drainage capacity of some backfill under extremely heavy rainfall. Due to its high drainage capacity, geocomposite is regarded as an appropriate material for drainage purposes in many geotechnical structures, including MSE walls. However, the installation of a geocomposite drain produces hydrologically complex boundary conditions, and unsaturated flow through the MSE wall becomes more complicated. This article reports a series of numerical simulations conducted to investigate the influences of MSE wall dimensions and drainage capacity on seepage responses inside the protected zone of the wall. The results indicated that the distance from the upstream water source to the drainage face (L) contributes most to the level of the phreatic surface inside the protected (reinforced) zone. Furthermore, a relationship existed between the permeability of the soil on the upstream side and the lowering of the phreatic surface due to increased geonet transmissivity. Results reported in this study might reinforce understanding of complex flow behaviors in MSE walls with back drain installation.