Model tests for anchored geosynthetic slope systems under dry and seepage conditions

ABSTRACT: The anchored geosynthetic system (AGS), which combines anchors or nails with natural or synthetic geotextiles to form a flexible reinforcing system, can stabilise steep soil slopes. In this study, a series of model tests on steep slopes of sandy soil were performed to investigate the mechanism and failure behaviour of slopes reinforced with two AGS systems. Particle image velocimetry was employed to measure the displacement of sand particles, and to identify the sliding zones. The effects of slope angle (50° and 70°), reinforcement type (wires and nails), anchorage force and seepage condition were investigated. The test results showed that application of a geotextile contributed to effectively retain soil particles, prevent accumulation of water pressure in the slope, and restrain the run-out distance when the slope failed. With regard to the failure mode, dry slopes anchored with stainless wires behaved as a wedge sliding, whereas a circular failure mode was observed in slopes subjected to seepage. On the other hand, the failure of the slope reinforced with nails was similar to a coherent block sliding. Limit equilibrium analysis was also employed to examine the stabilities of slopes, and proved itself a reliable method for such examination.