In the present study, performance of geosynthetic reinforced MSE walls backfilled with locally available marginal lateritic soil at the onset of rainfall infiltration was investigated. Two different types of geosynthetics reinforcements were used. One was a conventional type of geogrids usually used in MSE walls, and the other was composite geogrids. Seepage analysis, stability analysis and strength and deformation analysis were carried out on MSE walls with rainfall simulated for a duration of 3 days. In case of geogrid reinforced soil wall (GR-W), the suction within the backfill was lost completely at the end of 2.176 days of rainfall, whereas suction was maintained even at the end of 3 days of rainfall in walls reinforced with composite geogrids (CGR-W). From the stability analysis, it was observed that the factor of safety of GR-W decreased at the onset of rainfall infiltration with time and reached less than the desirable value of less than 1.5 in 2.125 days of rainfall. The factor of safety of CGR-W was maintained at 1.88 throughout the period of rainfall. The facing deformation in GR-W was found to increase, with a maximum of 3.2 times increase at the end of three days of rainfall. Similarly, there was an increase in maximum tensile load mobilized in the reinforcements in GR-W, whereas in the case of CGR-W, the influence of rainfall was negligible. From the present study, it can be concluded that the presence of composite geogrids improves the overall performance of MSE walls backfilled with marginal lateritic backfills.
Major part of Kerala is covered with lateritic soil. Lateritic soils, in general, can withstand high stress under unsaturated conditions. However, during rainfall infiltration, there is a tendency that the lateritic soil may undergo large and sudden deformation. In the recent past, Kerala experienced heavy rainfall induced distress. Associated with the rainfall event, a series of landslides and formation of cavities and subsidence of ground were observed in many parts of Kerala. Mechanically stabilised earth (MSE) structures such as reinforced soil walls and slopes can be used in landslide mitigation; especially in slide repair using the slide mass as the backfill. In the present study, soil was collected from a nearby site where landslide has occurred due to heavy rainfall. Experimental studies were conducted to study the collapse potential of the soil. An attempt was also made herein to investigate the deformation behaviour of geosynthetic reinforced soil slope resting on foundation soil subjected to rainfall induced subsidence.