Abstract: Rainfall is a crucial causative factor of landslide.In previous studies,water saturation is usually taken as the criterion for landslide occurrence;as a matter of fact,however,most landslides are still in an unsaturated state when they occur.The response of landslide deformation to changes in water content is investigated to further reveal the mechanism of rainfall-induced landslides.The correlation between soil moisture content and rainfall-induced landslides is examined through various methods inclusive of field monitoring,field model tests and indoor soil column infiltration tests.The results manifest that:1) The change rate of water content is a key indicator of rainfall-induced landslides.Due to rainfall impact,the rate of water content increment peaks and then results in the instability and damage of landslide.2) Rainfall process in the early stage is an important factor which affects the rate of water content change.The water content of soil is prone to surge under high-frequency rainfall after a prolonged drought.3) Heavy rainfall is the key influencing factor for the increase in the change rate of water content.Under the same initial conditions,the greater the rainfall intensity,the greater the change rate of water content,and the faster the change rate of water content reaches peak.

Key words: rainfall-induced landslide, previous rainfall process, heavy rainfall, moisture content, change rate of moisture content