Effects of extreme drought–rainfall on slope failure mechanisms: centrifuge modelling

Abstract

The extreme drought–rainfall seesaw is projected to occur with an increasing frequency. However, there still lacks a thorough understanding of its impacts on slope behaviour, in which desiccation crack plays a key role. To address this issue, a centrifuge test was conducted to investigate the effects of drought-induced desiccation crack on slope instability under extreme rainfall. During the test, the non-cracked slope was firstly subjected to extreme rainfall with 100-year return period. Subsequently, a long-term drying was applied to induce desiccation crack, and hence forming a cracked slope. The cracked slope is then subjected to an identical extreme rainfall. The non-cracked slope only exhibits swelling deformation, whereas for the cracked slope, a slip surface (2 m in depth) is clearly observed to initiate from one deep crack at crest. The global sliding failure of the cracked slope is mainly related to preferential flow, which could result in soil shear strength reduction.