Effect of locally accumulated crushed stone soil on the infiltration of intense rainfall: a case study on the reactivation of an old deep landslide deposit

An old landslide deposit situated in Deqin County, Yunnan Province, China, was used to investigate the effects of local accumulation of crushed stone soil on infiltration of intense rainfall. This study considers the infiltration process and landslide stability using finite-element method (FEM)-based models and a physical experimental model. The results show that reactivation of the old landslide was triggered by intense rainfall that occurred on 7–9 October 2012. The crushed stone soil played a key role in the rapid infiltration of rainfall deep into the landslide deposit. Accumulated rainfall and runoff water caused the formation of high pore water pressure in the crushed stone soil, which induced higher infiltration of the surrounding soil due to the higher gradient. The original slip zone was another key factor, as infiltrated water accumulated at the slip zone and form a high pore water pressure due to the lower permeability of the slip zone. The high pore water pressure that formed at the slip zone was the main factor triggering reactivation of the landslide during the rainfall.