降雨条件下高填方边坡稳定性研究

发布时间：2018-04-29 16:47

本文选题：高填方 + 边坡　；参考：《兰州理工大学》2017年硕士论文

【摘要】：随着我国社会经济的高速发展和国家对城市化进程的大力推进,西部地区基础设施建设获得空前的发展机遇。但是受到西部特殊的地质环境和独有的地形地貌条件的限制,不可避免的会遇到很多高填深挖工程,由此产生了大量的高填方边坡稳定性问题。相对于以往的填方边坡工程而言,当前高填方边坡变形及破坏机制日益复杂;特别是,不同降雨条件下高填方边坡稳定性研究匮乏,进而导致的高填方变形过大或失稳事故时有发生,如何在既有成果的基础上,提高高填方边坡稳定性分析的准确性,成为众多科技工作者亟待探索研究的关键问题。本文依托陇南成州民用机场项目,首先,通过非饱和土三轴试验进行了不同配合比填料的土水特征曲线实验研究,以此对其相对渗透系数进行了预测;其次,基于高填方边坡稳定性分析方法的系统分析,讨论了常用边坡稳定性分析方法的优缺点及适用条件;第三,采用Plaxis和GEOstudio软件对不同降雨条件下高填方边坡稳定性进行了深入分析,取得了一些有益成果和认识。具体研究内容和成果如下:1.通过对本项目特点与难点分析,进行了非饱和土三轴实验及其他室内土工实验,确定了不同配合比状态下边坡填料的抗剪强度、土水特征曲线、渗透系数等,为计算分析提供了准确参数。基于实验获取的土水特征曲线对不同吸力下的混合填料相对渗透系数进行合理预测;2.对于不同配合比的填料,在吸力较低水平下,配合比对渗透性影响不够明显;但是随着吸力的增加,土体饱和度不断减小,土石比为2:8的填料渗透系数衰减速度明显大于土石比4:6的填料;在饱和过程的后期,这种差异逐渐减小;3.通过有限元软件建立高填方边坡数值分析模型,分析了自然工况条件下,不同填料、不同坡率和不同坡高的边坡稳定性。结果表明填料土石比为4:6的边坡稳定性较高;同时,随着坡率和坡高的增大,边坡安全系数逐渐减小,此外,上部边坡坡率变化对整体稳定性影响较大。4.分析了最大降雨、不同降雨强度、不同降雨历时和前期降雨等条件下的高填方边坡稳定性,发现边坡在历史最大降雨条件下,表现出良好的稳定性能;随着降雨强度的增大,前期边坡稳定性迅速下降时间节点前移;随着降雨持续时间的增加,安全系数呈现三阶段的变化形式,即先缓慢降低,再急剧减小,最后趋于稳定。
[Abstract]:With the rapid development of China's social economy and the great efforts of the country to promote the process of urbanization, the construction of infrastructure in the western region has obtained unprecedented opportunities for development. However, due to the limitation of the special geological environment and the unique terrain and geomorphology in the west of China, many high fill and deep excavation projects will inevitably be encountered, resulting in a large number of stability problems of the high fill slope. Compared with the previous fill slope engineering, the deformation and failure mechanism of the high fill slope is becoming more and more complicated, especially, the research on the stability of the high fill slope under different rainfall conditions is scarce. As a result of excessive deformation or instability accidents of high fill slope, how to improve the accuracy of slope stability analysis on the basis of existing achievements has become a key problem for many scientific and technological workers to explore and study. In this paper, based on Longnan Chengzhou civil airport project, first of all, through the unsaturated soil triaxial test, the soil and water characteristic curve of different mix ratio fillers were studied, and the relative permeability coefficient was predicted. Based on the systematic analysis of high fill slope stability analysis method, the advantages and disadvantages of common slope stability analysis methods and their applicable conditions are discussed. The stability of high fill slope under different rainfall conditions was analyzed by Plaxis and GEOstudio software, and some useful results and understanding were obtained. The specific research contents and results are as follows: 1. Based on the analysis of the characteristics and difficulties of the project, the triaxial experiments of unsaturated soil and other indoor geotechnical experiments are carried out, and the shear strength, soil-water characteristic curve, permeability coefficient and so on of the slope fillers under different mixing ratios are determined. It provides accurate parameters for calculation and analysis. Based on the characteristic curves of soil and water obtained by experiments, the relative permeability coefficient of mixed fillers under different suction was reasonably predicted. For the fillers with different mix ratio, the influence of mix ratio on permeability is not obvious at the lower suction level, but with the increase of suction, the saturation of soil decreases continuously. The attenuation rate of the permeability coefficient of the fillers with the earth-rock ratio of 2:8 is obviously higher than that of the fillers with the ratio of soil to rock 4:6, and the difference decreases gradually during the latter stage of the saturation process. The numerical analysis model of high fill slope was established by finite element software, and the slope stability of different fillers, different slope ratio and different slope height was analyzed under natural working conditions. The results show that the slope stability is higher when the ratio of soil to rock is 4:6, and the slope safety coefficient decreases gradually with the increase of slope ratio and slope height. In addition, the slope ratio of the upper side has a great influence on the overall stability. The stability of high fill slope under the conditions of maximum rainfall, different rainfall intensity, different rainfall duration and previous rainfall is analyzed. It is found that the slope shows good stability under the condition of historical maximum rainfall, and with the increase of rainfall intensity, With the increase of rainfall duration, the safety factor presents a three-stage change form, that is, the slope stability decreases slowly, then decreases sharply, and then tends to be stable.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU43

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