软弱基座型滑坡形成机制离散元数值模拟研究

Formation Mechanism of Soft Foundation Landslide Based on Numerical Simulation of Discrete Element

软弱基座型斜坡具有“上硬下软”的双层坡体结构,其变形破坏方式和失稳模式也较为复杂。为了详细分析该类型边坡的变形破坏机制,以具有此类坡体结构特征的一库区古滑坡为例,在现场调查的基础上,采用地质分析法和离散元数值模拟方法研究天然、降雨和地震条件下边坡的变形破坏过程。结果表明:活跃的地质时期、陡峭的地形、复杂的地质构造和双层的坡体结构特征构成了该滑坡形成的必要条件,降雨和地震是诱发滑坡的主要外界因素;滑坡表现为倾倒变形和滑移-压制拉裂的复合型失稳模式;利用离散元数值模拟研究了坡体在天然重力、降雨和地震等不同条件下的变形破坏过程,计算结果显示降雨和地震均会导致滑坡发生,其中地震型滑坡具有持续时间更短、发生规模更大、运动距离更远的特点。

The soft foundation slope has a double slope structure with"hard and soft",and its deformation failure mode and instability mode are also complex.In order to analyze the denaturing failure mechanism of this type of slope in detail,an ancient landslide with such characteristics of slope structure was taken as an example,based on field investigation,geological analysis method and discrete element numerical simulation method are used to explore the formation process of landslide.The deformation and failure process of slope under natural,rainfall and seismic conditions is analyzed.The results are as follows.Active geological period,steep terrain,complex geological structure and double slope structure constitutes the necessary conditions of the landslide formation.Rainfall and earthquake are the main external factors.It is inferring that the landslide is characterized by a composite instability mode with toppling deformation and sliding and compression cracking.The slope deformation and failure process under different conditions such as gravity,rainfall and earthquake is simulated by using discrete element numerical simulation.The results show that both rainfall and earthquake can cause landslides.However,the earthquake type landslide has the characteristics of shorter duration,larger scale and farther motion distance.