泥石流与多重防护系统相互作用机理的研究

Debris flows are a particularly dangerous type of landslide and are of particular concern in the mountainous regions around the world where they routinely destroy property and claim lives. To intercept this hazardous phenomenon, multiple-barrier systems are a practicable means to mitigate reasonably large volume of debris flows. Current design of a multiple-barrier systems predominantly focuses on retention volume, however, there are no well-established scientific formulations for assessing the effect of the presence of debris-barrier interaction of multiple barriers on landslide debris mobility for overflow and landing mechanisms. Despite the high engineering value of multiple barrier systems, they are installed using empirical approaches globally. The danger in empiricism includes barrier spacing which enable debris to reaccelerate dangerously between barriers or even overshoot past subsequent barriers. Also, it is beneficial to understand how energy dissipates upon landing to be able to reduce the scale of subsequent barriers to enhance the sustainability of a multiple-barrier design. In this study small-scale physical tests using a 5-m long channel will be carried out to study the interaction between debris flow and multiple barriers. The channel inclination and particle diameter will be varied to study a wide range of flow types characterised by different pertinent dimensionless groups. Results from the physical model tests will then be adopted to calibrate a coupled Discrete Element Method with Computational Fluid Dynamics (DEM-CFD) model with a new pore pressure formulation. The calibrated numerical model will be used to carry out back-analyses to bear further insight by quantifying the energy dissipation, and mesoscopic flow characteristics such as stress, strain, and pore pressure. Finally, a field investigation will be carried out in Dongchuan, China to help verify scaled physical tests and numerical simulations. The combination of (i) physical model tests, (ii) numerical modelling, and (iii) field investigation will provide an improved understanding of debris flow interaction with multiple-barrier systems. Findings from this study will be invaluable for providing scientific recommendations and encourage practitioners to adopt multiple barriers systems for mitigating risk from debris flows worldwide.

泥石流是一种极度危险的山地灾害，其所到之处往往给当地人民或基础设施带来极大危害。当前的防灾减灾工程中，多重防护系统常被用于拦截方量较大的泥石流。然而，国内外现有的设计主要基于经验方法，以承载体积作为考虑因素，并无完善的计算方法考虑多重防护系统中泥石流-结构相互作用对于运动特性的影响，以及泥石流的溢流和着陆过程的机理。这种忽略了溢流和着陆过程的设计方法会使得下游的防护结构设计或过于保守或过于孱弱。深入了解泥石流的溢流过程以及着陆能量耗散过程可以指导下游防护结构的合理设计施工，从而保障人员及基础设施的安全。本项目将开展流槽实验来研究不同流态泥石流与多重防护系统的相互作用过程，建立考虑孔隙水压的流固耦合数值模型，比较分析野外实地数据与物理模型、数值模拟的结果，从而揭示泥石流与多重防护系统相互作用时溢流、着陆过程机理。

泥石流是一种极度危险的山地灾害，其所到之处往往给当地人民或基础设施带来极大危害。当前的防灾减灾工程中，多重防护系统常被用于拦截方量较大的泥石流。然而，国内外现有的设计主要基于经验方法，以承载体积作为考虑因素，并无完善的计算方法考虑多重防护系统中泥石流-结构相互作用对于运动特性的影响，以及泥石流的溢流和着陆过程的机理。在此背景下，本项目系统研究了泥石流与多重防护系统相互作用机理，主要取得了以下成果：（1）揭示了极端流态的泥石流与不同高度的多重拦挡结构相互作用过程，并提出了泥石流对多重防护结构的冲击荷载计算方法；（2）不同固体颗粒含量的泥石流溢流以及着陆机理；（3）新型底部开口式防护结构与不同粒径大小的泥石流相互作用机理以及对于多重防护结构的优化；（4）利用多重防护桩结构以及泥石流消能垫层优化下游防护结构的机理；（5）利用野外大尺度实验进行模拟挟带大块石的泥石流与刚性防护结构的相互作用及理论分析；（6）不同尺度的泥石流溢流及着陆过程机理及其与多重防护结构的相互作用。