STUDY ON EVOLUTION PROCESS OF LANDSLIDES TRIGGERED BY TYPHOON RAINSTORM

Typhoon storm-induced landslides are very common in the hilly and mountainous areas of southeast China. Understanding the evolution law of this kind of landslide failures is great helpful for the monitoring and early warning of rainfall storm landslides in this area. This study takes the Dehua Shishan landslide in Quanzhou,Fujian Province as a research object and combine the on-site geological survey data to establish a landslide physical and numerical model and to simulate the landslide deformation evolution process. After exploring the laws of seepage and landslide displacement in slope instability,results indicate the follows. (1)In the early period,the rainfall vertically infiltrates slope body with a high infiltration rate. The later infiltration rate decreases as the saturation of slope increases. The early rainfall can make the soil layer at the foot of the slope more prone to the saturation. (2)Rainfall infiltration is the main factor of slope instability. During heavy rainfall condition E3(The rainfall intensity is 100 mm·d^-1),the factor of safety decreases from 1.197 to 1.125. In the double peak heavy rain condition E4(The early rainfall intensity is 30 mm·d^-1,and the later rainfall intensity is 100 mm·d^-1),the factor of safety remains basically unchanged during the early rainfall from 1.197 to 1.188. When the rainstorm starts,the factor of safety drops to 1.060. (4)When early rainfall occurs firstly(rainfall intensity ≤30 mm·d^-1) and sudden heavy rainstorm occurs in the later period(rainfall intensity ≥100 mm·d^-1)in the experiment,the displacement suddenly increases by 20 mm,and then quickly develops to about 90 mm.