边坡强震稳定性分析与临界滑动面确定方法

发布时间：2018-03-22 13:03

本文选题：临界滑动面　切入点：竖向地震动　出处：《哈尔滨工业大学》2014年硕士论文　论文类型：学位论文

【摘要】：我国是一个地震多发的国家，地震灾害居世界之首。汶川地震表明，强震下边坡失稳破坏是最重要的震害形式之一。国内外学者在边坡地震稳定性分析方面做了大量研究。目前，边坡强震稳定性分析方法主要有拟静力法、Newmark滑块分析法、数值分析法、试验法和概率分析法等。拟静力法因具有概念简单、工程应用方便等优势，在实际工程中得到广泛应用。但是，传统的拟静力法通常预先假定边坡滑动面的形状，，并引入不同的假定条件减少边坡稳定性分析中求解未知量的个数，借助力和力矩平衡方程，计算出地震下边坡安全系数。但是，这类方法并不能真实的确定出地震下边坡滑动面的真实形状。显然，这类方法具有较明显的误差。此外，通常假定主要是水平地震惯性力控制着边坡地震失稳破坏，竖向地震动的影响可以忽略。但是，边坡震害实例还显示，竖向地震动对边坡动力稳定性影响显著。鉴于此，本文根据土的极限平衡理论，通过理论分析、数学解析方法和数值模拟相结合的手段，发展一种能够准确地确定边坡滑动面的真实几何形状和位置，以及考虑土体非均质性、孔压效应和竖向地震动作用的边坡地震稳定性分析与滑动面确定方法。本文主要研究工作与取得的若干认识如下：（1）考虑竖向地震效应的边坡临界滑动面简化方法：依据极限平衡理论，借助数学解析手段，保证地震中边坡满足土体应力和运动学容许准则，结合边坡变形的几何相容条件，构建出土条的非线性运动方程组，采用matlab中fslove函数进行求解，建立能够确定边坡地震稳定性分析与临界滑动面的基本理论与寻优方法，得到边坡运动学上容许的最小临界加速度，确定出边坡临界滑动面。应用土体强度参数加权平均方法考虑土层分界处边坡的潜在失效机理，运用平均孔压比法计算土体孔压影响效应，将上述方法拓展至可考虑土体孔压效应的非均质土质边坡中。最后，构建了可考虑竖向地震动对边坡稳定性分析与临界滑动面确定的解析方法。（2）采用土的弹－塑性多屈服面模型，以及水土动力耦合的有效应力原理，通过自由场边界条件模拟人工边界，同时为了土体液化分析采用土的两相介质理论，建立了可考虑土体液化效应的三维有限元分析模型与相应的计算方法，并验证拟建立分析方法的正确性；据此开发了界面友好的前后处理界面的计算平台SlopeSAR，分析了强震下边坡的动力响应特征。（3）最后，通过三维有限元方法计算结果检验简化方法的正确性，并开展简化方法在边坡地震稳定性分析与滑动面确定的中应用工作，重点讨论了简化方法中求解非线性方程组的方法的收敛性。同时，研究了土体强度对边坡临界滑动面的影响，考察了水平增量Δx对单个土条滑动面和边坡整体滑动面影响，分析了孔压、土体非均匀性和竖向地震动对边坡临界滑动面的影响。
[Abstract]:China is an earthquake-prone country, and the earthquake disaster ranks first in the world. The Wenchuan earthquake shows that. Slope failure under strong earthquake is one of the most important forms of earthquake damage. Scholars at home and abroad have done a lot of research on slope seismic stability analysis. At present, the main methods of slope strong earthquake stability analysis are pseudostatic method and Newmark sliding block analysis method. The pseudostatic method is widely used in practical engineering because of its advantages of simple concept and convenient engineering application. However, the traditional pseudostatic method usually presupposes the shape of slope sliding surface. Different assumptions are introduced to reduce the number of unknown variables in slope stability analysis, and the slope safety factor under earthquake is calculated by force and moment equilibrium equations. This kind of method can not really determine the true shape of slope sliding surface under earthquake. Obviously, this kind of method has obvious error. In addition, it is usually assumed that the horizontal seismic inertia forces control the slope seismic instability. The influence of vertical ground motion can be neglected. However, the example of slope earthquake damage also shows that vertical ground motion has a significant effect on the dynamic stability of slope. In view of this, according to the limit equilibrium theory of soil, the paper analyzes the effect of vertical ground motion on slope dynamic stability by theoretical analysis. By combining mathematical analytical method with numerical simulation, a method that can accurately determine the true geometric shape and position of slope sliding surface and consider the heterogeneity of soil is developed. Seismic stability analysis and sliding surface determination method of slope due to pore pressure effect and vertical ground motion. The main research work and some understandings obtained in this paper are as follows:. 1) the simplified method of slope critical sliding surface considering vertical seismic effect: according to the limit equilibrium theory, by means of mathematical analysis, the slope in earthquake meets the soil stress and kinematics tolerance criterion, combined with the geometric compatibility condition of slope deformation. The nonlinear motion equations of unearthed sliver are constructed and solved by fslove function in matlab. The basic theory and optimization method for determining the seismic stability and critical sliding surface of slope are established. The minimum critical acceleration of the slope kinematics is obtained and the critical slip surface is determined. The potential failure mechanism of the slope at the soil boundary is considered by using the weighted average method of soil strength parameters. The average pore pressure ratio method is used to calculate the effect of soil pore pressure, and the above method is extended to the heterogeneous soil slope which can take account of the pore pressure effect of soil. Finally, An analytical method for slope stability analysis and critical sliding surface determination considering vertical ground motion is proposed. (2) adopting the elasto-plastic multi-yield surface model of soil and the effective stress principle of soil and water dynamic coupling, the artificial boundary is simulated by the boundary condition of free field, and the two-phase medium theory of soil is adopted for soil liquefaction analysis. The three-dimensional finite element analysis model and the corresponding calculation method are established to consider the liquefaction effect of soil, and the correctness of the proposed analysis method is verified. Based on this, a calculation platform Slope SAR with friendly interface before and after treatment is developed, and the dynamic response characteristics of slope under strong earthquake are analyzed. Finally, the correctness of the simplified method is verified by the results of the three-dimensional finite element method, and the application of the simplified method to the seismic stability analysis and the determination of the sliding surface of the slope is carried out. The convergence of the simplified method for solving nonlinear equations is discussed, and the influence of soil strength on the critical sliding surface of slope is studied, and the influence of horizontal increment 螖 x on the slip surface of single soil strip and the whole sliding surface of slope is investigated. The influence of pore pressure, soil inhomogeneity and vertical ground motion on the critical sliding surface of slope is analyzed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU435

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