Characteristics of the Groundwater Seepage and Failure Mechanisms of Landslide Induced by Typhoon Rainstorm

Typhoon rainstorm usually causes a large number of landslides leading to property and life losses. The research on the characteristics of groundwater seepage and genetic mechanism of landslides, therefore, is of great significance in early warning and forecasting of typhoon-induced-landslide. Taking Zhonglincun landslide located in Zhejiang province as an example, the paper used finite element method to simulate the transient seepage field and stability of the landslide under two conditions including rainfalls with constant intensity of 200 mm/d and gradually increased intensity. The results showed that the characteristics of groundwater seepage under both conditions were almost the same. The groundwater level responded rapidly and finally approached near the contact between strongly and moderately weathered strata, in addition, the ground water overflowed from the slope toe. The rising speed of groundwater level, however, was faster and the range was larger under the first condition. The factor of safety was closely related to the ground water level and rainfall intensity. Under the former condition, factor of safety decreased rapidly with increased water level, the falling speed slowed down after the water level became roughly stable. Failure mode of the Zhonglincun landslide can be summed up as creep-crack and slide-crack-creep, while rise of water table, decrease of matrix suction and increase of pore pressure in the slope were the main reasons leading to the failure of Zhonglincun landslide.