泥石流孕育发生和发展的动力学模型与机理研究

In debris flow problem, the medium complexity of the debris mixture, the coupling dynamics of sand, rock and water in the mixture, and the interaction between flow and bed are the key features and the crucial issues for the understanding and prediction of the debris flow hazard. Lacking of in-depth mechanical study in these full coupling problems, the understanding on the debris flow remains rather inadequate to date. Focusing on the formation mechanism and dynamics of the debris flow, this project aims to derive new knowledge of the interaction between debris mixture and water, and build up coupled hydro-debris dynamic modeling theory. This research will start with the investigation on the mechanics properties of the debris mixture which is constituted with soil, rock and water, and then develop the theory on yield strength and rheological characteristics of the debris mixture, finally unravel the coupling mechanism in water-particle and flow-bed systems in this process. Then, a coupled model of seepage and deformation in soil-rock aggregate for debris flow generation process, and a dynamic coupled model for the flow process will be established. Based on these studies, the multi-processes coupling mechanism and the combination effects of various factors in debris flow breeding and generation will be revealed. The dynamic critical condition and diagnostic method on the occurrence of debris flow hazard will be proposed. The full coupled numerical simulation of the debris flow processes considering the interaction between flow and bed deformation will be achieved. Further understanding on the occurrence and evolution of the debris flow is expected. The project will drive a revolutionary shift paradigm in which debris flow processes are examined quantitatively through physically modeling practice. The proposed research turns out multidisciplinary in nature, and will certainly enrich the theory, methodology and application of the environmental mechanics subject.

泥石流的介质复杂性和水沙石以及流动与底床的强耦合是泥石流问题的显著特征，也是深入认识和科学预测泥石流成灾过程的关键科学问题。迄今仍缺乏对这一问题的深入力学研究，致使对泥石流的认识远不成熟。为此，本项目将针对泥石流的形成机制和运动规律这一关键问题，以土石水混合介质力学特性为切入点，采用力学理论和方法, 发展水沙混合介质强度和流变等力学特性的理论，探讨水-颗粒以及流动-底床之间的耦合作用机制，建立水渗流与土石混合体耦合作用模型和泥石流运动耦合模型；揭示泥石流孕育、发生的多因素综合作用和多过程耦合机理，提出泥石流发生的临界动力条件和诊断方法，实现对泥石流运动与底床冲淤变化的强耦合数值模拟，增强对泥石流发生、演变和发展规律的理解。为提高对泥石流灾害的定量预测能力提供科学理论和方法。同时，进一步深化对复杂介质和多过程耦合问题的认识，丰富和发展环境力学这门新兴交叉学科的内容、方法和理论。

介质复杂性和流动与底床强耦合是泥石流问题的显著特征，也是深入认识泥石流过程的关键科学问题，迄今仍缺乏对这一问题的深入认识。本项目重点研究了泥石流形成的力学机制和运动规律这一关键问题，在土石水混合介质的力学特性、泥石流发生的力学机制、以及泥石流动力学模型及运动演化规律等方面取得了创新性的研究成果，对泥石流复杂流动新理论的发展和泥石流灾害的预测和评估等具有重要意义。.1.提出了从细观力学描述土石水混合介质力学特性的新理念，建立了描述这类复杂介质从固态到流态本构/流变关系的力学理论和数值模型；研究了混合物固体、固-液转化及流体不同相态的力学特性，给出了含水土体新的强度准则及软化规律，发现了泥石流流变分层的特点，发展了包含颗粒两种主要作用方式的本构模型，首次给出了颗粒物质固液转化的临界态及本构关系。.2.建立了从地质体临界破坏、运动到流动各阶段的力学模型，实现了泥石流从形成到运动演化灾害链的数值模拟；研究了泥石流从孕育、发生及发展各过程的规律特点和力学过程；提出了颗粒物质破坏运动过程中的 “流变元”概念和流变率模型；揭示了滑坡转泥石流，以及山洪转泥石流的内在力学机制。.3.基于泥石流流变本构关系与运动状态相关的认识，建立了基于拟单相流的水沙床耦合泥石流运动模型、包含颗粒两种相态本构的三维泥石流两相流模型，以及目前最为完善的基于垂向积分的泥石流两相流模型，得到了实际泥石流事件的良好验证；发展了可方便用于工程应用的泥石流灾害数值模拟软件。.4.研究了泥石流运动的基本规律和特征，揭示了泥石流运动自增强、颗粒分选、能量转化等内在机制，提出了相间及颗粒间能量转化（做功）决定泥石流输运效率的新观点，有效地解决和回答了泥石流输运效率随初始体积增大而显著提高这一长期困扰人们的难题。.5.发表了学术论文81篇，其中SCI收录论文33篇，EI收录论文12篇。国内外学术会议大会邀请报告9人次。