Study on structural damage evolution of excavated slope subjected to earthquake and rainfall using electrical resistivity measurement

Abstract

Earthquake and rainfall are two major factors contributing to the slope failures. To examine the evolution of slope structural damage and the failure mechanism during the shaking and rainfall process, a model test of excavated slope subjected to earthquake and rainfall has been performed. The evolution of structural damage within the slope is considered as the changing process of porosity and crack development. The unique relation between of porosity and resistivity of unsaturated soil is utilized to reveal the spatial-temporal variation of slope structural damage by electrical resistivity measurement method. The testing results show that the shaking induced cracks appear on the surface of upper soil layer at the mid-height of slope model, and the structural damage could be both accumulated on the surface and inside the slope under seismic motion. The damaged area provides preference infiltration path for rainwater flow in the following raining process, resulting in the rapid increase of water content of slope interior. The sliding body extends and develops upwards to the slope crest under rainfall condition. The failure patten suggested by the structural damage parameter is verified by the dynamic response of slope model. The structural damage parameter using resistivity is able to show the spatial-temporal evolution of structural damage inside the slope quantitatively, and reflect the porosity change of soil under continuous earthquake and rainfall conditions. The evolution of structural damage reveals that the dynamic failure mode of excavated slope under earthquake and rainfall is the upwards-developed retrogressive sliding of upper soil layer. The evaluating method using resistivity measurement is particularly promising for field test of slope where it can be used to monitor the structural damage change of soil mass subjected to complex environment conditions.