Abstract: Rainfall induced landslides frequently occurred in Fujian Province, and it is important to reveal the evolution of landslides triggered by rainfall and its patterns to study the formation mechanism of geological hazards and risk warning criteria in Fujian Province. A numerical model for the Houting landslide in Yongtai County, Fuzhou City, Fujian Province is established and calibrated with field monitoring data to study the changes of landslide seepage field and its stability response under the rainfall effect. The study shows that: (1) the landslide forms a local high negative pore pressure zone under strong rainfall, and causes the water flow to converge to this area, and the response of soil moisture content is positively correlated with rainfall, and the response is timely; (2) the stability coefficient of the landslide decreases rapidly under strong rainfall, and recovers after rainfall, but the recovery rate is much smaller than the decline rate, and cannot recover to the initial value; (3) the strength of the soil decreases after wet and dry cycles, which causes the landslide under the same conditions to stability decreases, so after several rainfall cycles, its stability may decrease resulting in landslides; (4) under strong rainfall, the surface displacement grows steadily and there is still some growth after the rain due to water infiltration.

Key words: Rainfall, Landslide Stability, Dry and Wet Cycles, Numerical Simulation