土石坝渗流场与应力场耦合及边坡稳定分析

发布时间：2018-12-31 08:21

【摘要】：渗流问题不仅是影响土石坝的安全稳定性的一个关键因素,且与其经济性息息相关。受坝址开发条件等因素的限制,在西北地区尤其是沙漠和半沙漠地区所修建的土石坝工程,渗流及稳定问题成为制约这些工程设计与施工的关键问题之一。本文结合正在修建的水利枢纽工程,水库大坝为均质土坝,坝基存在强透水性砂层,因此对此工程进行渗流稳定安全分析研究,对于保证水库安全以及提高工程效益具有现实意义。对蓄水前后考虑干、湿态参数的影响进行分析;并针对渗流的防渗措施设计合理的方案,基于渗流与应力耦合分析的基本理论和方法,建立分析模型,围绕不同的防渗方案(防渗墙深入坝肩、坝基的不同长度),对渗流量及渗透坡降等渗流要素进行分析;并结合强度折减法,懫用有限元软件Abaqus对此工程进行坝体稳定性分析,得出位移分布图以及塑性贯通区位置分布图。本文的主要工作和成果如下:(1)阐述了坝体填土在蓄水前后考虑干、湿态参数的影响在Abaqus中实现计算的思路,并且总结和探讨计算中的土体单元拉裂、剪切破坏修正方法,联系具体的工程计算案例,应用Duncan-Chang E-B本构模型模拟计算土体的竣工后、蓄水后和考虑干、湿参数的蓄水过程,并对所得的应力场以及位移场计算结果进行了分析。(2)介绍了土体渗流场与应力场之间的耦合作用机理及其有限元格式;计算了考虑渗流场与应力场耦合作用下土石坝在不同工况下的渗流,得到孔隙水压力、流速分布云图,并且得到具体的渗流量和渗透坡降值,判断防渗墙对渗流量的影响以确定合理设计方案。首先建立渗流场-应力场耦合模型,计算在不同的防渗方案下,考虑渗流-应力耦合作用后,并由此确定此土石坝的防渗墙深入坝肩长度为50m。(3)使用有限元程序Abaqus中特有的场变量设置以此来实现强度折减,在五种不同工况下确定最危险的塑性贯通区滑裂面以及最小安全系数,并根据规范选定两种工况下进行地震惯性力的影响计算,得到塑性贯通区滑裂面及最小安全系数。
[Abstract]:Seepage problem is not only a key factor affecting the safety and stability of earth-rock dams, but also closely related to its economy. Restricted by the conditions of dam site development, seepage flow and stability have become one of the key problems in the design and construction of earth-rock dams built in northwest China, especially in desert and semi-desert areas. In this paper, the reservoir dam is a homogeneous earth dam, and there is a strong permeable sand layer in the dam foundation, so the seepage stability and safety analysis of this project is carried out. It is of practical significance for ensuring reservoir safety and improving engineering benefit. The effects of dry and wet state parameters before and after storage were analyzed. Based on the basic theory and method of seepage and stress coupling analysis, the analysis model is established, which revolves around different seepage prevention schemes (seepage wall is deep in dam abutment, dam foundation is different in length). The seepage factors such as seepage volume and seepage slope are analyzed. Combined with the strength reduction method, the stability of the dam body is analyzed by using the finite element software Abaqus, and the displacement distribution map and the position distribution map of the plastic through-through area are obtained. The main work and results of this paper are as follows: (1) the idea of calculating the effect of dry and wet parameters before and after the dam filling is expounded in Abaqus, and the methods of soil element tensile fracture and shear failure correction in calculation are summarized and discussed. The Duncan-Chang E-B constitutive model is used to simulate and calculate the process of water storage after the completion of soil mass storage and considering the dry and wet parameters. The calculated results of stress field and displacement field are analyzed. (2) the coupling mechanism between seepage field and stress field and its finite element scheme are introduced. Considering the coupling of seepage field and stress field, the seepage of earth-rock dam under different working conditions is calculated, and the pore water pressure and velocity distribution cloud diagram are obtained, and the specific seepage flow and seepage gradient are obtained. Determine the influence of the cutoff wall on the seepage flow to determine the reasonable design scheme. Firstly, the coupling model of seepage field and stress field is established, and the seepage stress coupling is considered under different seepage control schemes. It is determined that the length of the impervious wall of the earth and rock dam is 50 m. (3) the specific field variables in the finite element program Abaqus are used to reduce the strength of the dam. The most dangerous slip surface and minimum safety factor of the plastic through zone are determined under five different working conditions, and the influence of seismic inertial force is calculated under two conditions according to the code, and the slip surface and the minimum safety factor of the plastic through area are obtained.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV223

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