| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 107 === Rainfall infiltration continually causes serious threats on the stability of natural slopes and earth retaining structures and has been identified as one of the main causes for failures of geosynthetic-reinforced soil (GRS) walls. The fact that failure cases continue to occur despite existing established knowledge means there is a need to reevaluate what is understood of the effect of rainfall on GRS structures. This study therefore aims to investigate the performance of geogrid-reinforced walls with different backfill qualities subjected to rainfall.
Experiments were conducted on reduced-scale GRS walls in accordance to the similitude law: wall geometry and reinforcement properties were scaled down, while backfill properties remain unchanged. Rainfall was introduced into the model by means of a suspended irrigation system. The wall deformation and failure process of the GRS wall model were also observed with a camera and analyzed via digital image analysis.
For model walls built with silty sand, failure occurred in the form of interlayer sliding or excessive deformation. Water infiltration data showed water can accumulate up to the top of the wall. Wall deformations were large and had a cantilever shape, and the mobilized tensile load was concentrated at the top of the wall. For a model wall built with clean sand, the performance is overall better: failure was limited to vertical interlayer cracks, wall deformation was smaller and more uniform, water infiltration data showed good patterns, and distribution of mobilized tensile load was uniform across the reinforcement layers. These results will give better insights on design by increasing the required factor of safety against breakage and pullout for routine design calculations involving the simplified method, and by ensuring the top of the wall stays unsaturated through proper drainage measures or by applying an impermeable layer.
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