| Summary: | 碩士 === 國立臺灣大學 === 土木工程學研究所 === 107 === Geosynthetic reinforced soil walls (GRS walls) are considered as one of the best among all slope stabilization methods. However, in-situ soil (marginal backfill) was often adopted to adhere to a local regulation which specifies that the excavated and backfilled soils should be balanced. Loss of matric suction and soil shear strength due to rainfall infiltration is a main cause of the failure of GRS walls with marginal backfill.
A series of reduced scale model tests was performed to investigate the performance of GRS walls with marginal backfill under rainfall conditions and to propose improved methods for practical design. The effects of the three improved methods, namely, reduction of reinforcement spacing, selection of better quality backfill, and adoption of sand cushions, were evaluated. Rainfall duration was set such that the wall model became fully wet or the monitored value reached steady state. The volumetric water content and the pore water pressure were monitored and the wall displacement was recorded throughout the tests. Mobilized reinforcement tensile strain was evaluated and the strain distribution in the wall models was analyzed via post image processing.
The test results indicated that the reduction of reinforcement spacing can effectively improve the stability of the wall; meanwhile, the displacement was diminished. In addition, applying granular backfill can indeed avoid the loss of matric suction; however, tensions cracks or critical failure surface developed suddenly. Finally, the adoption of sand cushions is complementary beneficial to the performance of GRS walls with marginal backfill under rainfall condition. Not only was the interface friction enhanced but the deformation characteristic was improved. The sand cushions also accelerated the dissipation of water.
|
|---|
