降雨条件下大型慢速滑坡变形与孔压波动互馈机制研究

Large slow landslides often cause widespread and long-term damage and threat to highways, railways, bridges, hydropower stations and buildings because of their large numbers, long duration and imperceptible slow deformation. However, the importance of this type of landslides has been greatly underestimated at present, compared with high speed landslides. Domestic and foreign scholars generally agree that the deformation of the landslides is closely related to the fluctuation of pore water pressure caused by rainfall in the slope body. But because of the complexity, randomness and uncertainty of the large slow landslides during their evolution process, the feedback mechanism between the deformation and the fluctuation of pore water pressure is not still fully understood at present. It is especially lack of effective and real-time quantitative deformation prediction models with clear physical mechanism under rainfall condition in the practice of slow landslides. In view of this, this project will take a typical slow landslide in China as the research object and study its dynamics mechanism under seasonal rainfall condition. The study is based on field investigation, indoor and outdoor tests, supplement monitoring and theoretical analysis, physical simulation and numerical calculation method. Finally, we will build a physical mechanism model of considering the feedback of the intermittent deformation and pore water pressure fluctuation of the landslide. The model will provide a scientific theoretical basis for quantitative prediction and disaster prevention and mitigation of large slow landslides.

大型慢速滑坡因其具有数量多、持续时间长、变形缓慢且不易察觉等特点，常常对公路、铁路、桥梁、水电站和建筑物等造成广泛的、长期的危害和威胁。但相比高速滑坡，目前此类滑坡的重要性已被大大低估。国内外学者普遍认为大型慢速滑坡的变形与季节性降雨引起的坡体内孔隙水压力的变化密切相关。但由于大型慢速滑坡变形演化过程的复杂性、随机性和不确定性，目前对季节性降雨条件下大型慢速滑坡变形与孔压波动互馈机制的认识和理解仍很不充分，特别缺乏行之有效的、且具有清晰物理机制的大型慢速滑坡变形演化的实时定量预测模型。鉴于此，本项目拟以我国典型的大型慢速滑坡为研究对象，通过现场调查、室内外试验和补充监测以及理论分析、物理模型试验和数值计算等手段，在揭示降雨条件下慢速滑坡变形演化动力学机理的基础上，建立降雨条件下慢速滑坡间歇性变形与孔压波动互馈的物理机制模型，从而为大型慢速滑坡的定量评价预测及防灾减灾提供理论依据。

大型慢速滑坡因其具有数量多、持续时间长、变形缓慢且不易察觉等特点，常常对公路、铁路、桥梁、水电站和建筑物等造成广泛的、长期的危害和威胁。但相比高速滑坡，目前此类滑坡的重要性被大大低估。国内外学者普遍认为大型慢速滑坡的变形与季节性降雨引起的坡体内孔隙水压力的变化密切相关。但由于大型慢速滑坡变形演化过程的复杂性、随机性和不确定性，目前特别缺乏行之有效的、且具有清晰物理机制的大型慢速滑坡变形演化的实时定量预测模型。鉴于此，本研究首先系统搜集了国内外101个典型慢速滑坡实例，对其类型、特征、诱发因素及成因机理和危害对象及危害特征等进行了深入系统的梳理和总结，阐释了国内外慢速滑坡孕育演化的主要驱动力和部分慢速滑坡转化为快速滑坡的相关机理，并探究了慢速滑坡对不同危害对象的致损响应关系。然后，通过对典型慢速滑坡滑带土样进行“剪切―保持―剪切”（SHS）室内试验，研究处于残余状态下的剪切面在不同法向应力、不同保持时间和排水条件下的强度恢复情况，揭示了滑带土的自愈合现象是慢速滑坡产生间歇性变形的重要内在机制。在此基础上，以两个典型大型慢速滑坡为例，通过现场调查、室内试验以及理论模型和数值模拟等手段，在分析慢速滑坡间歇性变形与降雨、地下水、孔隙水压力的响应规律及机制的基础上，将慢速滑坡蠕变过程中的水文地质条件（Hydrogeology）、力学破坏机理（Mechanism）和滑坡变形（Deformation）三者有机结合起来，从一维和二维的角度，建立了大型慢速滑坡的水文-力学-变形耦合模型，实现了基于动力学机理模型的慢速滑坡变形定量预测。相关研究成果有助于我们加深对慢速滑坡的总体认知，可以为大型慢速滑坡的定量评价预测及防灾减灾提供理论依据。