【作者】 程怡；

【导师】 刘君；

【作者基本信息】 大连理工大学 ， 水工结构工程， 2010， 硕士

【摘要】 能源问题一直是制约国民经济又好又快发展的一个主要问题。水电能源作为一种清洁能源在我国发展很快。随着西部大开发、西电东送以及南水北调等国家级大工程项目的开工建设,高坝大库的建设越来越多。我国水电能源集中在西部和西南地区,这些地区恰是我国的强震区。在高坝大库中,土石坝占了相当大的比重。而土石坝的边坡和坝基的稳定是大坝安全的基本保证。虽然极限平衡法有很多优点,但在处理三维稳定问题时,还很不成熟,而有限元强度折减法处理三维问题则要方便很多。本文以FLAC3D为计算平台,选取面板堆石坝和黏土心墙坝两种坝型,运用强度折减法计算不同工况下坝坡的稳定安全系数,并分析坝体最危险滑裂面的位置,具体工作如下：(1)最危险滑裂面的确定。强度折减计算只能直接给出稳定安全系数,而最危险滑面的准确位置需要进一步分析确定。在现有的一种基于等效塑性应变二维临界滑裂面搜索方法基础上,推广出三维滑裂面的搜索方法。采用强度折减法计算边坡稳定时,处于临界破坏状态下的边坡,其潜在滑裂面是由塑性区中沿竖直方向上等效塑性应变最大的点所组成的。通过这一原理,寻找到这些三维数据点,然后运用NURBS曲面法和最小二乘法对这些数据点进行三维拟合,得到最危险滑裂面。(2)对均质面板坝运用拟静力法计算其在不同坝高、坝坡、地震烈度以及河谷系数下的稳定安全系数,并分析坝体滑裂面的位置。计算结果表明：坝越高,坝坡越陡、地震烈度越大、岸坡越宽,安全系数越小；安全系数与坝坡高宽比值呈线性关系,与坝高、地震烈度系数、河谷系数等呈非线性关系。根据计算结果,文中给出了这些因素与安全系数之间的经验计算公式。同时发现地震烈度的大小对滑裂面位置有较大的影响,随着地震烈度的增加,滑裂面滑出点位置逐渐向坝顶靠近。(3)对黏土心墙坝运用拟静力法计算其在不同坝高、坝坡及地震烈度下的稳定安全系数,并分析最危险滑裂面的位置。计算结果表明：坝高、坝坡及地震烈度对安全系数影响规律与面板坝类似,但其滑裂面的滑出点位置大部分都在坝高1／5的位置,滑弧较深。更多还原

【Abstract】 Energy has been a main problem that restricts the rapid development of the national economy and society. As a kind of clean energy, hydropower develops rapidly in China. Along with the development of the West Regions, West-East electricity transmission project, South-to-North Water Transfer project are under way, there are more and more constructions of high dam and giant reservoir coming up. Our country’s hydropower energy is centered mainly in western and southwestern regions, where are coincidentally meizoseismal areas in our country. The rockfill dam takes up a great proportion in high dam. What’s more, the basis of dam security is stability analysis of slope.Although the limit equilibrium method has many advantageous, it is still not mature when dealing with three dimensional stability analysis problems. Compared with it, the finite element-strength reduction technique is more convenient when doing so. FLAC3D analysis software is used as the main calculating tool in this thesis. The strength reduction technique is applied to analyze the factor of safety and the location of the critical slip surface in two kinds of dams, which are concrete faced rockfill dam and clay core wall dam. The work of this thesis is as follows:(1) The location of the critical slip surface. With the strength reduction technique, only a factor of safety can be obtained directly, and the critical slip surface is usually determined through more analysis. There is a new approach for searching the critical slip surface based on equivalent plastic strain in the two-dimensional slope stability analysis, and this thesis extends this method into three-dimensional case. Once the slope is led to the limit equilibrium state by means of the strength reduction technique, a plastic zone will go through the slope from the toe to the top. Along each of the vertical lines in some planes, the point with the maximum equivalent plastic strain is sought out in this study. All of these points form a functional data. Lastly, these control points could constitute a smooth surface by the NURBS method and the least square method, and then the critical slip surface will be built.(2) The factor of safety is calculated by means of pseudo-static method under circumstance of different height of dam, gradient of slope, earthquake intensity as well as shape of valley. Of course, the location of critical slip surface is analyzed as well. Through analysis, a result is concluded that the higher dam is, the steeper slope is, the greater earthquake intensity is, the wider valley is and the smaller safety factor is. What’s more, the factor of safety has a linear relation with the gradient of slope and a non-linear relation with the other elements. Through the result, an empirical correlation is provided in this thesis. And it’s found that earthquake intensity has a great effect on the location of critical slip surface. The location of critical slip surface ascends gradually to dam crest with the increase of earthquake intensity.(3) A pseudo-static method is also used to study the dynamic stability of clay core wall dam under different circumstances, and the location of critical slip surface is also analyzed. By analyzing the stability of slope, it is known that the effect of height of dam, gradient of slope and earthquake intensity on safety factor is similar to concrete faced rockfill dam, but the location of critical slip surface is deeper, and about 1/5 height of the dam.更多还原