Analysis on lag effect of typhoon-induced landslide: A case study of typhoon “Lekima” in Qingtian County, Zhejiang Province

Typhoon landing is frequent in the southeast coastal areas of China, and the typhoon-induced landslide caused by associated rainstorms has caused serious economic losses and casualties. Some studies have made some achievements in the slope hydrological response process and stability analysis of single-peak and multi-peaks typhoon rainstorms, but research on mechanism analysis on the hysteresis effect of typhoon-induced landslide is lacked. Therefore, taking “Lekima” in Qingtian county, Zhejiang Province as an example, based on the statistics of the number and rainfall of typhoon-type landslides, this paper constructs 16 groups of slope models with different structural combinations to simulate the seepage-stability changes of slopes under different rainfall conditions during the landing of a typhoon. The results show that there are still 26.4% landslides in Qingtian county after typhoon “Lekima” left the land, which is lagging. The stability of slopes with different structural combinations is the lowest after landing, which is 13.82% lower than that before typhoon landing. Under the action of typhoon landing rainstorm, the slope is the most sensitive among the influencing parameters of slope stability structure in Qingtian county. It is considered that rainfall at different landing stages of the typhoon will lead to the difference of infiltration characteristics of the slope, thus forming a hysteresis effect. The conclusion has a certain guiding significance for the early identification of typhoon-induced landslides in this area.