Case Study on Instrumenting and Monitoring Geosynthetic-Reinforced Pile-Supported Mechanically Stabilized Earth Wall Built over Soft Soil

Abstract

This paper presents a case study on instrumenting, monitoring, and finite element modeling (FEM) of geosynthetic-reinforced pile-supported (GRPS) mechanically stabilized earth (MSE) walls. The GRPS-MSE wall was monitored using various instruments such as piezometers, earth pressure cells, shape-acceleration arrays (SAAs), and strain gauges. The performance criteria included efficacy, stress concentration ratio (SCR), differential settlement, and reinforcement tension. Collected data, such as excess pore-water pressures, contact pressures on pile and soft soil, differential settlements, and lateral displacement of MSE wall, were analyzed thoroughly. A 3D FEM was also developed to simulate the GRPS MSE wall, and the results are in good agreement with field data. The results demonstrated significant load transfer from soil to piles as a result of soil arching, yielding 30–32 SCR. The field efficacy was measured at 37.69 %, while the FEM efficacy was estimated as 42.4. Strains in geogrids within the geosynthetic-reinforced load transfer platform (GLTP) system were under 1%, less than the 5% maximum recommended by FHWA. The maximum differential settlement measured between pile cap and soft soil from SAAs is 7.1 mm, while it is estimated to be 8.3 mm from FEM. The MSE wall exhibited low lateral displacement (<25 mm), indicating enhanced stability because of GLTP. The comparison between five analytical GLTP design methods showed that the CUR226 methods gave the closest results to field measurements and FEM results. This study offers crucial insights into leveraging GLTP and MSE walls in highway construction.