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水动力作用下泥石流源区固体物质可移动判别模型研究
Alternative TitleStudy on the movable critical model of solid materials under hydro-dynamical condition in debris flow area
杨顺
Thesis Advisor欧国强
2014
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline岩土工程
Keyword可移动固体物质 饱和渗流 表面径流 临界判别模型 原位观测
Abstract水动力作用下泥石流源区固体物质失稳、移动形成泥石流是山区流域最为常见的灾害类型之一,尤其汶川地震后,频繁暴发的泥石流直接影响到灾区人民生命财产安全和灾后恢复重建工作。目前,对流域内沟坡系统固体物质失稳、起动、运动过程等理论及试验研究较多,而固体物质在水动力作用下是否移动的临界问题研究较少。 针对泥石流源区固体物质在水动力作用下是否移动的临界问题,本研究从泥石流源区松散固体物质和水动力条件入手,提出可移动固体物质概念;通过力学分析,建立其在渗流、饱和渗流+表面径流共同作用下的动力表达式、抗力表达式以及可移动厚度临界判别式;进而通过多物理场数值模拟和同尺寸物理模型试验进行验证;此外,对泥石流源区土体在非饱和渗流条件下含水量、孔隙水压力等时空变化特征进行了原位观测和分析,为将来非均质粘性等复杂坡体物质在水动力作用下的可移动性问题研究奠定基础。 通过分析研究,初步得到如下结论: (1)基于力学平衡原理,提出了可移动固体物质概念及其定义,并与传统的泥石流松散固体物质、动储量、有效固体物质等术语进行了区别 可移动固体物质为“当水动力(渗流、表面径流)和重力分量的合力不小于阻力时,土层中临界厚度范围内的土体”,基于力学平衡原理导出,具有明确的物理力学意义。 (2)建立了水动力(饱和渗流/表面径流)和重力分力共同作用下坡体可移动固体物质判别模型 首先对可移动固体物质进行分类,然后选择平直型坡体为研究对象,建立饱和渗流、饱和渗流+表面径流共同作用两种水动力方式下的可移动固体物质判别模型。 在此基础上,开展了数值仿真实验(多物理场COMSOL Multiphysics)和物理模型试验。数值仿真实验主要对饱和渗流条件下的渗流力和可移动厚度与理论模型进行了验证;室内物理模型试验对饱和渗流、饱和渗流+表面径流条件下的动力和可移动厚度与理论模型进行了验证。结果表明理论模型合理。 (3)通过原位观测,分析了非饱和渗流条件下斜坡土体含水量与孔隙水压力时空变化特征 固体物质的移动现象不仅发生在饱和渗流/表面径流条件下,而且还会发生在非饱和渗流环境(一般发生在陡坡地形上的堆积物)。通过斜坡土体原位观测,分析了固体物质在非饱和渗流作用下土体含水量和孔隙水压力的时空变化特征。结果表明:土体含水量变幅随深度递减,同位置孔隙水压力峰值随时间滞后于含水量峰值。
Other AbstractSoild material in debris flow source area under hydrodynamical effect which transform to form debris flow is one of the most common disaster patten in the mountain area, especially post 5.12 Wenchuan earthquake, the high frequency debris flow events take menace to mountain people’s safety of life and properties directly, as well as reconstruction work etc. Currently, more theory and experiment research on solid materials instability mechanism, debris flow initiation, movement process etc of slope-gully system but less research on the moveable critical condition of solid materials are under hydro condition as seepage flow and thinner surface flow. Thus, with this critical problem of solid materials in debris flow area under hydrodynamic condition effect, through the solid materials and water condition as entry point, propose the concept of movable solid materials first. Then, use mechanical analysis to build the dynamics formula, resistance formula and the movable critical model of the two hydrodynamical condtion (constant seepage flow, constant seepage and surface flow) respectively. Third, with multi-physics numerical simulation method and the same scale physical experiment are to verificate the movable critical models. Last, analyze the temporal and spatial characteristics of water content and pore water pressure under unsaturated seepage flow in debris flow area, which provide the research on the complex slope materials as heterogeneity viscous with the right direction in future and the significant theoretical value. Through analysis, main conclusions are as following. (1) Propose the Concept of Movable Solid Materials Based on Mechanism Balance and Make a Distinction Among the Traditional Solid Materials, Dynamical Reserves of Loosen Solid Materials and Valid Solid Materials et al. The definition of movable solid materials is that the composite force of hydro- dynamic and gravity is larger than solid materials resistant, the solid materials within the critical thickness is the movable soild materials, which proposed based on mechanism balance and possess clear mechanical sense. (2) Set up the Movable Critical Model of Solid Materials under the Hydro- dynamic and Grivity Effect (Saturated Seepage Flow/ Surface Flow) Firstly, take a classification of the movable solid materials; then choose straight slope as research object to establish the movable critical model of solid materials by two type’s hydro effect (saturate seepage flow, constant seepage and surface thinner flow). On this basis, lauch numerical simulation (Comsol Multiphysics method) and flume experiment. The numerical simulation verificate the seepage force and critical thickness with movable critical model; while the flume experiment validate the dynamic force and critical thickness with theory model under the saturated seepage and saturated seepage + surface flow. Results reveal a certain reasonable. (3) Through Field Observation, Analyze the Temporal and Spatial Characteristics of Water Content and Pore Water Pressure under Unsaturated Seepage Flow Condition in Debris Flow Area Solid materials are moving not only happened in saturated seepage flow/surface flow, but also in the unsaturated environment (such as deposit on the steep topography). Through field observation of slope body, it analyzes the variation of water content and pore water pressure in unsaturated area; the results show that the water content magnitude decrease with depth, the peak value of pore water pressure was in a lag of water content in time.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/7859
Collection山地灾害与地表过程重点实验室
Recommended Citation
GB/T 7714
杨顺. 水动力作用下泥石流源区固体物质可移动判别模型研究[D]. 北京. 中国科学院研究生院,2014.
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