مهندسی عمران شریف (Aug 2019)
EXPERIMENTAL STUDY ON PERFORMANCE OF REINFORCED SOIL EMBANKMENT OVERLYING SHALLOW VOID
Abstract
Underground voids can cause many problems and dangers to the structures in urban areas and this issue can be intensified with time. These voids are made naturally or artificially and may be situated near or underneath of structures. Since shallow voids are located near to the ground surface, their impact can be extended to ground level and cause significant ground settlements or collapse of the voids. Soil reinforcement is currently utilized in the form of physical stabilization over the void crowns. The purpose of this research is to experimentally investigate the impacts of soil reinforcement arrangement on the performance of soil embankment and void stability. Therefore, a physical model designed with void diameter equal to 20cm and the scale of 1:50. The model satisfied plane strain conditions along void axes. For this purpose, poorly graded silica sand (SP) was used for the soil strata in the model tank and a thin plate of aluminum which coated with thin sand layer, was used to represent soil reinforcement. Performance of soil reinforcement was studied through the development of 15 different models. These models loaded sequentially by void air pressure reduction. Void air pressure and soil settlement at failure point, and also soil settlement after void collapse were measured to assess the performance of these models.Experimental results indicated that the performance of reinforced soil was improved when the depth of reinforcement placement increased from the soil surface and the number of reinforced layers were added. The number of reinforcement layers that would improve the performance considerably was limited to a certain number (i.e. two layers in this study). Finally, the results indicated that using reinforcement with more width around the void area would improve soil stability in the model, but this improvement can only be significant under a certain reinforcement width to void diameter ratio (i.e. three times of the void diameter in this study).
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