边坡地震稳定性分析拟静力法的改进

发布时间：2018-02-04 03:25

本文关键词： 边坡地震改进的拟静力法强度折减法旋转坐标法　出处：《重庆大学》2015年硕士论文　论文类型：学位论文

【摘要】：在公路、铁路和水利等工程的建设中,往往需要修建边坡,边坡工程对我国的国民经济建设有着不可估量的重要作用。人工边坡为基础设施建设提供有力保障,同时也为人们生产生活提供了巨大的便利。然而边坡的稳定性问题也严重影响到公路、铁路和水利等工程施工和运营的安全性。我国处在世界上两个最大地震发生的最集中地带之间,并受到印度板块、菲律宾海洋板块和印度板块的相互挤压,使得地震断裂带不断发展。因此,对在地震作用下边坡的稳定性分析显得十分重要,并且具有很大的现实意义。尤其是我国在2008年经历了汶川地震之后,特大地震对于山区滑坡造成的危害使得更多的学者重视边坡在地震作用时稳定性的研究。为此,本文就边坡地震稳定性分析中的拟静力法做了一些初步的研究工作。本文的主要内容及结论如下:①首先,提出边坡稳定性分析的理论基础,再分别阐述静力作用下和地震作用下边坡稳定性的分析方法。基于静力和地震作用下边坡稳定性分析的研究现状指出地震作用下拟静力分析的优缺点,从而引出本文要研究的内容;②对拟静力法进行全面的分析,针对在竖向条分时计算水平地震力与抗滑力矩时的误差进行分析得出以下结论:计算地震惯性力有很大的误差,同时抗滑力矩计算结果比真实的抗滑力矩偏低。由于人们过于看重水平地震力对边坡的产生破坏,而忽略了竖向地震力的影响,因此本论文中地震加速度考虑是斜向的。在考虑斜向加速度的情况下,改进了拟静力法即:由竖向地震惯性力与土条重力引起的滑动力矩和抗滑动力矩,采用竖向条分计算;由水平地震惯性力引起的滑动力矩和抗滑动力矩,采用水平条分计算;最后再进行叠加;③利用有限元分析的合理性,考虑土体应力与应变关系,采用强度折减法进行边坡的拟静力强度折减法来分析稳定性。利用改进的拟静力法同强度折减法对同一个算例进行对比,分析计算的结果发现强度折减法安全系数偏小。通过分析还发现在强度折减法的模型中,地震惯性力的水平地震力与竖向地震力是对整个模型而言的,然而在改进拟静力法中并没有考虑最危险圆弧滑面底部弓形体的拟地震力,仅仅只是分析了圆弧滑面以上条分土条所受到的水平地震力、竖向地震力和重力。这就说明改进的拟静力法仍然需要进一步完善;④基于改进的拟静力法与强度折减法的对比所发现的问题,提出了一种新的计算方法,即通过旋转原来的坐标将地震力与重力进行矢量叠加,以形成合力,并在合力的方向上建立与合力垂直的新的X坐标,使得地震的边坡稳定问题变为经过土体参数和边坡几何尺寸修正形成新的边坡,从而只需进行静力分析即可。为印证新方法的可行性,使用改进的拟静力法与强度折减法对同一个算例进行计算,将其结果同之前的两个安全系数进行对比,发现旋转坐标法结论与强度折减法结论接近,且数值上都偏小,说明采用旋转坐标法避开了改进的拟静力法没有考虑最危险圆弧滑面下部地震力的问题,该分析方法是可行的,并没有影响拟静力分析方法本身;⑤为提高旋转坐标的实用性,考虑了水下边坡在地震作用下安全系数的计算。通过旋转坐标法、静力计算法与理论推导公式等传统的方法进行对比,分析其结果的准确性,发现数值分析的方法与理论分析的方法所得出的结论相差不大,这说明对于水下边坡的旋转坐标法可以用于地震作用下的水位边坡分析;⑥以一个实际的边坡为例,采用传递系数法计算一般工况下边坡稳定性并采用改进的拟静力法和旋转坐标法校核地震作用下边坡的稳定性。结果表明旋转坐标法得到的稳定系数比改进的拟静力法偏小,采用该方法计算更偏于安全,因而更合理。
[Abstract]:In the construction of highway, railway and water conservancy projects, often requires the construction of slope, plays an important role in national economic construction of slope engineering in our country. To provide effective protection of artificial slope for the infrastructure construction, but also provides great convenience for the production and life of the people. However, the stability problem of slope is also seriously affected highway, railway safety and water conservancy project construction and operation of our country. Among the most concentrated areas of the largest earthquake occurred in the two world, and by the India plate, squeezing Philippines Ocean plate and India plate, with the continuous development of the earthquake fault. Therefore, the stability of slope under earthquake analysis is is very important, which has great practical significance. Especially after our country has experienced the Wenchuan earthquake in 2008, earthquake for the harm of the mountain landslide More and more scholars pay attention to the study of slope stability under earthquake. Therefore, this article makes some preliminary research on the pseudo static analysis of seismic stability of slope. The main contents and conclusions of this paper are as follows: firstly, the theoretical basis of slope stability analysis, and then describes the analysis methods of slope stability under static load and under the earthquake. Research status analysis of slope stability under earthquake static and points out the advantages and disadvantages of static analysis based on quasi earthquake, which leads to the content of this paper to study; second, to conduct a comprehensive analysis of the pseudo static method, aiming at the vertical slice when calculating the horizontal seismic force and anti sliding moment of the error the analysis draws the following conclusions: the calculation of seismic inertial force has a great error, and anti sliding moment calculation results than the low anti slip torque because people focus too much on the real. The level of earthquake damage to the slope, while ignoring the influence of the vertical earthquake force, so this paper is inclined to consider the earthquake acceleration. Considering the oblique acceleration induced by the improved quasi-static method: sliding moment caused by vertical seismic inertia force and the gravity of the earth and anti sliding moment. The vertical slice method; sliding moment caused by horizontal seismic inertial force and anti sliding moment, using horizontal slice calculation; finally the rationality of superposition; using finite element analysis, considering the relationship between stress and strain, the quasi-static strength reduction of slope by strength reduction method to analyze the stability. By using the improved quasi-static method with strength reduction method on the same example compared the results found that safety factor of strength reduction is small. Also found in the model of strength reduction method through the analysis. Horizontal earthquake and vertical earthquake force earthquake inertia force of the whole model, however, in the modified pseudo static method is not intended to force the most dangerous slip surface seismic bottom toxoplasmatic consideration, just above the analysis of circular slip surface of soil strip by horizontal seismic force, vertical seismic force and gravity. This shows that still need to further improve the improved quasi static method; the comparison of pseudo static method and strength reduction method based on improved problems, puts forward a new calculation method, namely the earthquake force vector superposition and gravitational force by coordinate rotation of the original, to form a joint force, and establishment and force the new X coordinates in the vertical direction of the force on the slope stability problem of earthquake into the soil parameters and slope geometry correction to form a new slope, thus requiring the static analysis for the new evidence. The feasibility of the method, using the pseudo static method and strength reduction method with a calculation example of improvement, the results of the two safety factor before the same comparison, found the rotating coordinate method and strength reduction method is close to the conclusion conclusion, and the values are small, the rotating coordinate method to avoid the improved static method does not consider the most dangerous part of the seismic force of circular slip surface, the analysis method is feasible, and has no effect on pseudo static analysis method itself; in order to improve the practicality of rotating coordinates, considering the calculation of underwater safety coefficient of slope under earthquake. By rotating coordinate method, static calculation method with the theoretical formula, comparing to the traditional, the accuracy of analysis results, found the method of numerical analysis and theoretical analysis of the conclusion of the difference, it shows that the water slope under rotation Coordinate method can be used for the analysis of water level slope under earthquake; according to an actual slope as an example, by using transfer coefficient method to calculate the slope stability under normal conditions and using the quasi static method of slope stability and the rotating coordinate method checking under earthquake. The results show that the improved stability coefficient obtained rotating coordinate method is smaller than the quasi static method is improved, using the method of calculation is more secure, and more reasonable.

【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU435

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