考虑土水相互作用的流滑三维运动过程数值模拟研究

Flowslide is regarded as one of the most insidious form of landslide for its lack of pre-failure indication. In general, flowslide is characterized by rapid movement, fluid-like motion, and long run-out distance. Soil-water interaction plays a key role in run-out behavior of flowslide, it can influence the complex time and space dependent changing of pore water pressure, hence influence the run-out behavior. Present numerical studies take flowslide mass as one phase material without considering soil-water interaction. So the results, especially lateral depositing and depositing modes, can't truly represent the run-out behavior. The aim of this project is to conduct numerical study on 3D run-out behavior of flowslide considering soil-water interaction, through calibration of material test, experiment and case study, based on discrete element method coupling with fluid. Through this research, correlation between micro and macro parameters can be drawn, numerical model can be built to present the initial conditions of flowslide, and boundary conditions of changing boundaries can be assigned. This research can help to understand the mechanism of high-speed movement and depositing modes, it can also promote the level of numerical assessment of flowslide hazard.

流滑是滑体呈流态运动的一类滑坡灾害，具有突发性强、高速、远距等特点，一旦发生往往造成灾难性的后果。流滑过程中土水共存，且两者相互作用会导致孔隙水压力时空变化，从而影响运动过程。然而当前流滑运动过程的数值模拟均假设滑体为单相物质，没有考虑运动过程中的土水相互作用及其对运动的影响，导致模拟结果，特别是弯道超高堆积和沉积模式，与实际有较大的偏差。本项目拟通过材料试验、模型试验和流滑实例校正，将固液耦合理论融入离散元模拟中，获取微观固液耦合参数与宏观参数的关系，探讨反应流滑初始状态的离散元建模方法，研究流滑运动过程中动态边界的边界条件设定方法，最终建立可以考虑土水相互作用的流滑三维运动过程数值模拟技术。通过本项目的研究，有望阐释流滑体高速运移与沉积形态的形成机理，进一步提升流滑风险的数值预测方法。

流滑是滑体呈流态运动的一类滑坡灾害，多由降雨诱发于尾矿坝、黄土、填土边坡、城市固体废弃物堆填体等松散体中，具有突发性强、高速、远距等特点，一旦发生往往造成灾难性的后果。项目从流滑水力灾变过程研究的角度出发，分为水文响应过程及其灾变机理与运动过程数值模拟两个方面开展研究。其中在滑坡水文响应过程及其灾变机理方面，主要研究了极端降雨条件下填土高边坡的水文响应、降雨流滑地下水优势渗流路径、降雨入渗条件下边坡的水气两相响应；在滑坡的运动过程数值模拟方面，主要通过颗粒流模拟研究了不同细粒含量条件下填土的细观结构、红石岩滑坡三维堰塞过程数值模拟、填方边坡降雨失稳运动过程模拟；在数值模拟方法方面，主要基于颗粒有限元法（PFEM）、颗粒流法（PFC）与物质点法（MPM）三种方法，开展了降雨流滑运动过程模拟对比分析。本项目开展的降雨流滑诱发机理与运动过程模拟对于定量预测流滑的持时、速率、冲击力、滑动距离、覆盖范围等灾害效应，对于流滑风险分析、治理措施等减灾防灾工作具有重要的意义。