Case history on failure of geosynthetics-reinforced soil bridge approach retaining walls: Fid-Bau Portal

Case history on failure of geosynthetics-reinforced soil bridge approach retaining walls

Xiao, Chengzhi / Gao, Shan / Liu, Huabei / Du, Yanqing

Abstract Six geosynthetic-reinforced soil (GRS) retaining walls supporting bridge approach roads of an overpass bridge in China exhibited a series of structural problems after 18 years of service. Field investigations demonstrated that the major structural problems consist of excessive lateral facing displacement, settlement and damage of facing panels, and pavement cracks above the GRS retaining walls. The structural problems were mainly caused by inadequate backfill compaction behind the facing, rain water infiltration, the settlement of foundation soil, and reinforcement ageing. Among the six GRS walls, a 22-m-long section collapsed after mild rain in July 2016, and the failure surface in the collapsed zone was mainly located 0.5–0.9 m away from the back of facing panels along the wall height. The field investigation found that external water filtration into the backfill behind the facing panels, and the breakage of connection between reinforcement and facing panels were the main causes of the failure. The connection breakage resulted from the ageing of PP reinforcement strips, and the critical issue of PP reinforcement ageing in complex backfill environment was pinpointed. Remedial measures of the failed section and reinforcing techniques of the remaining GRS walls were briefly presented in the end.

Highlights • Field observations were carried out to investigate the main structural problems for 6 bridge approach GRS retaining walls. • Ageing of PP reinforcement strips was the main cause of the failure of a 22 m-long partial collaspe GRS wall. • The as-built design of the GRS walls was evaluated and the remedial measure for the failed section was presented. • Case History on Failure of Geosynthetic-Reinforced Soil Walls Supporting Bridge Approach Roads.