Drought-induced stability reduction in unsaturated geotechnical applications

This paper addresses numerically, using an upper bound theorem approach, the impact of drought on the stability of three unsaturated geotechnical aspects: bearing capacity, slope and tunnel stabilities. Post the approach validation, a parametric study was carried out for each problem at a low degree of saturation range, slightly before the residual suction and up to a near-dry level, for two different simulated soils to investigate the drought influence at various retention behaviors. The numerical results showed a significant reduction in stability across all problems, attributed to the impact of the drought, which negated the benefits that can be acquired owing to the effect of suction. A relatively small decrease in suction up to the dry state was sufficient to cause the maximum reduction in stability for coarser soils. However, the stability reduction was seen higher for the finer soils for the same range of suction decrease when compared with the coarser soils.