基于滑带土强度劣化的库水复活型滑坡渐进失稳机理研究

Study on progressive instability mechanism of reservoir water resurrection laudslide based on strength deterioration of sliding zone soil

为研究库水复活型滑坡的渐进失稳机理,采用颗粒流离散元模拟滑坡的变形破坏全过程.通过离散元PFC2D双轴压缩试验进行微观参数标定,而后建立等比例计算模型,对不同分段滑带进行强度折减,模拟滑坡的渐进失稳过程,并采用“分段式滑面底渗法”的模型试验方法进行验证.结果表明,数值模拟结果与模型试验结果吻合较好.滑带土强度衰减是诱发滑坡失稳的重要因素.滑坡体失稳主要经历了坡面微裂缝产生、后缘破裂面贯通、底滑面蠕滑失稳、直至整体滑移等渐进破坏过程.库岸滑坡表现为蠕滑-拉裂的牵引式滑坡破坏模式.各级滑块仅有一条主裂缝,滑块内部伴生有次生裂缝.滑坡体表层发生拉破坏,底滑面主要发生剪破坏,中间部分为拉剪综合的动平衡状态.

To study the progressive instability mechanism of reservoir water reactivated landslide,the particle flow discrete element was used to simulate the whole process of deformation and failure of the landslide.The microscopic parameters were calibrated by the discrete element PFC2D biaxial compression test,and then a equal proportion calculation model was established to simulate the progressive instability process of the landslide by strength reduction of different sectional sliding zones.The model test method of“sectional sliding surface infiltration method”was used to verify the results.The numerical simulation results are in good agreement with the model test results.The strength attenuation of the sliding zone soil is an important factor to induce the instability of the landslide.The instability of the landslide body mainly experiences the gradual failure process of the micro-cracks on the slope surface,the penetration of the trailing edge fracture surface,the creep instability of the bottom sliding surface,until the overall sliding.The reservoir bank landslide is usually characterized by a creep-cracking traction landslide failure mode.There is only one main crack in the sliding blocks at all levels,and there are secondary cracks in the sliding blocks.The surface of the landslide body is tensile failure,the bottom sliding surface is mainly shear failure,and the middle part is a comprehensive dynamic equilibrium state of tension and shear.