|Alternative Title||Debris flow formation model combining hydrological processes and stochastic material supplying simulation in watershed|
|Thesis Advisor||崔鹏 ; 刘昌明|
|Place of Conferral||北京|
|Keyword||泥石流 阵流模拟 土体补给 随机过程 汇流模型|
泥石流往往被看成一定降雨条件下土体与水流混合的结果，从这种程度上讲，流域水文过程是泥石流形成的主线，坡面物质补给过程和沟谷汇流过程的强度决定了泥石流的规模和频率，其随机性和间歇性，则导致了泥石流的阵流现象。论文针对流域泥石流的形成过程，研究流域水文特性，构建了流域次径流的产汇流模型；研究降雨条件下土体浅层失稳的随机特征，建立了物源补给泥石流的随机过程模型；进而结合运动波方程，构建了流域泥石流的汇流模型，实现流域阵流模拟。取得了以下主要成果：1. 以典型区域为例，分析了流域泥石流的形成条件和形成过程，总结了流域泥石流的系统性和阵流特征，明确了本文的研究对象。从系统的角度来讲，泥石流的形成过程可以概化为一个多级系统的演化过程，可划分为坡面过程、沟谷过程和汇流过程。物质补给过程的间歇性和分支汇流的非同步性从源头上决定了流域泥石流形成的阵性现象，因此可以看作是是流域系统的一种“主动”行为。2. 研究了泥石流多发流域蒋家沟的降雨空间分布特征和径流年内分布特征，发现海拔是影响小流域降雨空间差异的最主要因素，建立了基于海拔的降雨空间插值方法，以坡面为子流域划分依据，在子流域内部和单坡面上根据地形精细概化产流单元，利用SCN-CN模型进行产流模拟，用运动波方程和动力波方程分布模拟坡面流和河道流，建立了流域次径流产汇流模型。流域次降雨总径流量的模拟效果良好，证明了模型的有效性。3. 野外源地实验发现，降雨过程中松散土体浅层失稳补给泥石流的过程可看作是一个随机序列，具有时间上的间歇性、空间上的离散性和规模上的涨落性；土体活动时间间隔和规模分别随雨强指数式减小和增大；时间过程可用Poisson分布描述，规模过程可用Pareto分布描述，其概率分布参数都与雨强有良好的统计关系；在此基础上建立了坡面土体补给泥石流的随机过程模型，单坡源土体失稳过程的模拟和流域尺度上土体补给总量的模拟结果都证明了模型的有效性。4. 基于质量守恒连续方程和泥石流流速基本公式，建立了泥石流汇流运动波方程，在其解析解的快速计算方法基础上，结合流域内水、土计算结果，建立了泥石流汇流模型，并在蒋家沟进行了次降雨-泥石流的过程模拟；从结果上看，泥石流总量误差在可接受范围之内；从过程上看，实现了流域的阵流模拟，且实际发生的泥石流均在模拟泥石流发生的时段内。尽管仍存在一定的缺陷，模型也为流域泥石流的流量过程模拟提供了一种新的思路和方法。;
Debris flow is generally considered as a combining result of runoff and slope failures during the rainfalls. Therefore, the debris formation process can be simulated based on the hydrological process and the material supplying process modeling. This research focused the mechanism and simulation of aforementioned processes, and built a debris flow formation model, using for debris flow surges simulation. 1. The objective of this research was identified through comparing the formation conditions and processes between debris flows in watersheds and on a single slope. The formation processes can be regarded as an evolution chain from the mass failure on slope, to initial debris flows formation through soil-water interaction in gully, and then to eventual debris flow via influx processes in watershed. The surges resulted from the discontinuities and non-synchronization of the aforementioned processes, and therefore can be regarded as a reflection of self-organization of debris flow in watersheds.2. A hydrological model was built and the event rainfall-runoff processes were simulated Jiangjia Ravine. A new spatial interpolation method was build based on the spatial analysis of relationship between rainfall difference and elevation, for the modeling input. Sub basins were divided based on the slope distribution, and was finely generalized based on the precise terrain. The SCS-CN method was used for runoff yield and kinematic wave and dynamic wave equations were used for overland flow and river flow, respectively. The observed runoff hydrographs were reorganized and analyzed for the modeling test. The result indicted the model can be used for the hydrological process simulation in the corresponding watershed. 3. A series of experiments in debris flow source regions were carried out, and indicated that the shallow failures on slope can be regarded as a “random series”, with the time-intermittent, spatial-discreteness and magnitude fluctuation. The time interval and average magnitude were verified to decrease and increase exponentially with the rainfall intensity imposed, respectively. The Poisson and Pareto distributions were used to describe and simulate the time and magnitude in the material supply processes resulting from the slope failures, and the key parameters in the distributions were identified based on their statistic relations with the rainfall intensities. The reasonability of the theory and the availability of the stochastic model were verified by the simulation result of slope failure processes on a single slope, and the total material amount calculation in the watershed.4. By deriving the fast solution algorithm of analytic solutions, the kinematic wave equations, which were built based on the unified form of debris flow movements equations and the mass conservation continuity equation, were used for describing debris flow movement processes in the channel. The confluence system was built based on the runoff and soil materials calculation results, and an assumptive linear water-soil interaction principle. The hydrographs of debris flow surges in Jiangjia Ravine were simulated successfully, and moreover, the total amount and debris flow occurrence time shows acceptable precisions. This theory and model provide an innovative approach for debris flow surges, despite the mismatching of debris flow peak discharge.
|郭晓军. 基于产汇流和土体随机补给的泥石流形成过程[D]. 北京. 中国科学院大学,2016.|
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