地质科技通报 (Mar 2022)
Evolution mechanism of rainstorm-induced shallow landslides on slopes covered by arbors considering the influence of wind-induced vibration
Abstract
Shallow landslides on slopes covered by trees are often the result of the coaction of heavy rainfall and strong winds under extreme weather, such as severe convection or typhoons. The Fanzhangzu landslide, a rainstorm-induced shallow landslide in the mountainous area in southern Anhui, was taken as a case study. Through field investigation and meteorological data analysis, it is considered that in addition to rainstorms, wind loads may also promote landslide initiation. To reveal the mechanism of the landslide evolution process, including initiation and postfailure movement, the stability under actual rainfall conditions was first analysed based on the infinite slope model. Then, by using a DPRI ring shear apparatus, undrained cyclic shear tests and natural drainage residual shear tests were carried out on two kinds of soil samples taken from the surroundings of the arbor roots and the sliding surface, respectively. The results show that ① The increase in porewater pressure in the sliding surface results from rainfall infiltration, and the subsequent decrease in stability is the direct reason for the initiation of the Fanzhangzu landslide during rainstorms. ② For the saturated soils around the arbor roots, high excess porewater pressure can be built up under cyclic shear loading resulting from wind-induced vibration, which leads to local failure in the shallow layer and elevates the potential for instability of the Fanzhangzu landslide. ③ The residual strength of the sliding surface soil has a significant positive shear rate effect, so the Fanzhangzu landslide does not show the characteristics of high-speed and long-distance movement in the postfailure stage, which is consistent with the field investigation.
Keywords
