滑坡碎屑流-结构动力相互作用计算模拟及灾害定量风险分析

In the last decades, with the development of economy, it is a large raising investments and inputs in landslides stabilization, monitoring and early-warning system, observation and prevention operated by mass people in our country. Nevertheless, several landslide-induced debris flows occurred in recent years caused severe damages on lives and constructions. Most of these landslides originate suddenly from the high location of a mountain and progress downward quickly in a mode of flow-like debris flows and have a huge destructive power. Because the origin area of the failure masses is located at the high place of mountain it is very difficult to find the unstable rock masses and construct stabilizations to prevent potential landslide prior to mobilization. To reduce the risk, passive measures (for example, the construction of defense structures in order to stop, deviate or slow down the flow) and an early quantitative risk assessment are recommended. However, the development of analytical and numerical methods for the rational assessment of impact force generated by landslide-induced debris flows is still a challenge as these flow events are highly dynamic, unpredictable and inherently complex in nature. In this project, the dynamic interaction mechanisms between the landslide-induced debris flows and structures are studied. Methods such as field geology survey, physical model tests and numerical simulation are used to solve the problems of impact and fluid-structure interaction. The contact models, energy-balance model and structure damage model will be coupled with dry granular models to simulate the dynamic interaction events. The outcomes of this project are expected to be used in evaluation of the effectiveness of defense structures, optimal design of defense structures, and the quantitative risk assessment of this type of landslides.

近几十年来，我国在滑坡防治、监测预警以及群测群防上投入很大，也取得了较好的效果。然而，近年发生的一些大型高位滑坡碎屑流灾害，由于发生突然、运动距离远、冲击破坏力强，给下游造成了严重的灾害。高位滑坡的滑源区常常比较隐蔽，且地形上处于高位导致主动加固工程难以实施。因此，采取被动防护工程并结合灾害的定量风险分析是减少此类灾害损失的有效途径。滑坡碎屑流-结构动力相互作用是进行工程防护结构设计和灾害定量风险评估面临的最重要的问题和挑战。项目基于灾害现场调查，采用理论分析、物理模型试验和数值模拟的手段，研究碎屑流冲击接触过程中的能量交换、应力扩散、结构损伤破坏过程机制，提出块石冲击力和碎屑流冲击压力的计算模型，耦合接触模型、能量守恒、结构破坏模型，发展基于流固耦合的数值方法，解决滑坡碎屑流灾害防护结构效果评价和优化设计、灾害定量风险评价的问题，为高位滑坡-碎屑流灾害防治和风险评估提供理论和技术支持。

近几十年来，我国在滑坡防治、监测预警以及群测群防上投入很大，也取得了较好的效果。然而，近年发生的一些大型高位滑坡碎屑流灾害，由于发生突然、运动距离远、冲击破坏力强，给下游造成了严重的灾害。高位滑坡的滑源区常常比较隐蔽，且地形上处于高位导致主动加固工程难以实施。因此，采取被动防护工程并结合灾害的定量风险分析是减少此类灾害损失的有效途径。滑坡碎屑流-结构动力相互作用是进行工程防护结构设计和灾害定量风险评估面临的最重要的问题和挑战。项目研究主要内容包括滑坡碎屑流单体块石的冲击力计算；碎屑流-结构冲击压力计算；滑坡碎屑流冲击特性、防护结构效果评价及优化设计；基于滑坡-结构物动力相互作用的定量风险评估等。.本研究数值计算主要采用物质点法，由于物质点法兼具欧拉法和拉格朗日法的优点，避免了有限元法在大变形方面的不足，同时又可以对材料应力应变进行计算，在求解流体-结构相互作用问题时具有一定的优势。基于物质点法采用摩擦系数弱化模型和应变软化本构模型模拟滑体在运动过程中的解体破碎过程，在汶川地震大光包滑坡运动过程模拟中取得了很好的效果。在滑坡碎屑流拦挡结构方面，把滑坡碎屑流考虑为干颗粒流体材料，结构为固体材料，通过设置合理的接触模型，实现滑坡碎屑流和结构之间的流固耦合计算，为滑坡碎屑流拦挡消能结构设计提供了技术基础。采用DP、牛顿流体、Bingham流体模型，对不同流体的运动过程以及和结构之间的动力作用过程进行模拟，模拟粘性泥石流在有齿槛和没有齿槛的水槽中的运动，并与物理模型试验进行了比较验证，实现了泥石流等流体-结构之间的动力过程计算模拟。. 本项目研究探索滑坡碎屑流、泥石流等的运动动力机制，以及和防护结构之间的相互作用过程的计算模拟，相关成果可为滑坡定量风险分析和减灾工程提供重要支持。