降雨诱发坡面泥石流的数值模拟研究

发布时间：2018-03-10 02:35

本文选题：坡面泥石流　切入点：变形过程　出处：《重庆交通大学》2015年硕士论文　论文类型：学位论文

【摘要】：坡面泥石流是我国山区公路沿线的重要地质灾害,主要受降雨控制。本文在国家自然科学基金项目“坡面泥石流精细演化机制研究”(编号41071017)资助下,对模型试验结果进行数值模拟研究,取得如下成果:(1)分析了坡面泥石流的形成影响因素,主要研究了地形条件和水源条件对坡面泥石流形成过程的影响。地形条件是坡面泥石流发生的控制因素,它决定了泥石流发生后的破坏形式。水文条件主要是降雨的作用,降雨是坡面泥石流发生的主要诱发因素,它改变斜坡岩土体的水文地质条件,而且降雨也是坡面泥石流形成的必备条件,它不仅为泥石流的形成提供丰富的水源,降雨还为泥石流的运动提供动力作用。(2)孔隙水压力的增长与累积降雨量有着密不可分的关系,累计降雨量增长越快,孔隙水压力增长幅度反而小。以实验中5号点为例,在相同的降雨量情况下,在降雨历时8h试验中的,累积降雨量平均增长速度为12.5mm/h,孔隙水压力从-0.00433Mpa增长到0.0041Mpa,增长幅度为0.00843Mpa。在降雨历时4小时试验中,累积降雨量平均增长速度为25mm/h,孔隙水压力从-0.00619Mpa增长到0.0031Mpa,增长幅度为0.00919MPa。(3)依照模型试验的尺寸和数据,采用ANSYS14.5中FLUENT模块结合大变形模拟的数值模拟方法,对降雨诱发坡面泥石流的演化过程作了数值模拟,通过模型的建立、参数的设置、网格的划分、边界条件的设定和模型计算等步骤,得到了坡面泥石流的变形云图和变形数据。通过对部分点的变形分析,得到了土体单元的变形规律,通过对剖面的分析,得到了整个坡面土体的整体变形规律,通过对整个坡面变形的分析,得到了坡面泥石流在降雨作用下的变形趋势。通过对比分析了模型试验和数值模拟两种情况下,坡面在降雨作用下的变形趋势基本相同。(4)模拟了不同坡度下坡面泥石流土体的变形过程,得到不同坡度下,坡体的变形云图和变形数据。通过对不同坡度下坡体的变形云图的分析,发现坡度越大,土体变形越大,且随着坡度的增大,坡体后缘土体的变形增长较快,而前缘土体变形增长较慢。
[Abstract]:Slope debris flow is an important geological hazard along highway in mountainous area of China, which is mainly controlled by rainfall. This paper is supported by the project of National Natural Science Foundation "study on fine evolution mechanism of slope debris flow" (No. 41071017). The numerical simulation results of the model test results are obtained as follows: 1) the factors affecting the formation of debris flow on the slope are analyzed. This paper mainly studies the influence of terrain condition and water source condition on the forming process of debris flow on slope surface. Terrain condition is the controlling factor of debris flow on slope surface, which determines the failure form of debris flow after occurrence, and the hydrological condition is mainly the function of rainfall. Rainfall is the main inducing factor of debris flow on slope, which changes the hydrogeological condition of slope rock and soil, and it is also the necessary condition for the formation of debris flow on slope. It not only provides abundant water for the formation of debris flow. The increase of pore water pressure is closely related to the accumulated rainfall. The faster the accumulated rainfall, the smaller the increase of pore water pressure. Under the same rainfall condition, the average growth rate of cumulative rainfall was 12.5 mm / h, and the pore water pressure increased from -0.00433Mpa to 0.0041Mpa. the increase was 0.00843Mpa. in the 4-hour rainfall experiment, the average growth rate of cumulative rainfall was 12.5mm / h, and the pore water pressure increased from -0.00433Mpa to 0.0041Mpa. The average growth rate of accumulated rainfall is 25mm / h, the pore water pressure increases from -0.00619Mpa to 0.0031Mpa. the increase range is 0.00919MPa.m3) according to the size and data of the model test, the numerical simulation method of FLUENT module combined with large deformation simulation in ANSYS14.5 is adopted. The evolution process of slope debris flow induced by rainfall is numerically simulated. Through the establishment of model, the setting of parameters, the division of grid, the setting of boundary conditions and the calculation of model, etc. The deformation cloud map and deformation data of debris flow on slope surface are obtained. Through the deformation analysis of some points, the deformation law of soil element is obtained, and the integral deformation law of the whole slope soil is obtained by analyzing the profile. Through the analysis of the deformation of the whole slope surface, the deformation trend of debris flow on the slope surface under the action of rainfall is obtained. The deformation trend of slope surface under rainfall is basically the same. 4) the deformation process of debris flow soil under different slope degrees is simulated, and the deformation process of debris flow soil is obtained under different slope degrees. The deformation cloud map and deformation data of slope body. By analyzing the deformation cloud map of slope body with different slope degrees, it is found that the larger the slope degree is, the larger the deformation of soil is, and with the increase of slope, the deformation of soil in the back edge of slope body increases rapidly. However, the deformation of the front soil increased slowly.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P642.23

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