甘肃天水地区强降雨诱发黄土-泥岩滑坡机理实验研究

在甘肃天水地区每年由降雨诱发的黄土-泥岩滑坡灾害事故很多,给当地人民生命财产造成巨大损失。为探索该类斜坡的滑动破坏过程与机理,在野外地质调查、工程地质钻探及岩土体力学测试的基础上,通过室内大型物理模型实验,研究“上部黄土+下部泥岩”二元结构类型斜坡在强降雨作用下的动态变形演化过程,揭示该类斜坡的破坏机理和破坏模式。结果表明:强降雨作用下斜坡变形破坏以滑动破坏为主,水分的作用主要表现为增加土体自重、引起土体强度降低、降低结构面的抗滑力、产生孔隙水压力及降低有效应力等几个方面,斜坡的破坏模式则主要表现为坡肩侵蚀→微裂隙产生、发展、贯通→斜坡局部滑动破坏→斜坡整体滑动破坏。研究结果对天水地区该类滑坡的早期识别有重要的参考意义,可为该类滑坡的防灾减灾提供科学依据。

Experimental Study on Mechanism of Heavy Rainfall-induced Loess-mudstone Landslides in Tianshui Area,Gansu

Rainfall-induced loess-mudstone landslide disasters are common every year in the Tianshui area (Gansu Province), causing significant loss of life and property. Based on field geological survey, engineering geological drilling, and rock and soil mechanics analyses, and through laboratory large-scale physical modelling experiment, we explore the dynamic deformation process of heavy rainfall-induced landslides (which are characterized by loess-mudstone bimodal structure), and reveal the failure mode and mechanism for this type of landslide. The results show that the slope deformation is mainly manifested as sliding damage under heavy rainfall. The role of water is mainly on increasing the soil weight and pore water pressure, and decreasing the soil strength, effective stress, and sliding resistance of the structural surface. Meanwhile, the failure mode of landslide is mainly manifested by slope shoulder erosion→microcrack growth and interconnection→local failure→overall sliding failure. Our findings are important for early-stage landslide recognition and provide scientific basis for landslide-related disaster prevention in the region.