土钉支护基坑中位移矢量角预测基坑失稳的意义研究

发布时间：2018-03-04 23:27

本文选题：基坑坡体　切入点：位移矢量角　出处：《青岛理工大学》2013年硕士论文　论文类型：学位论文

【摘要】：论文的研究内容基于国家自然科学基金与山东省自然科学杰出青年基金项目,开展了对基坑坡体安全性问题数值计算的研究和分析,根据土体的变形特性,采用非线性有限元方法,通过对数值模拟的结果分析,探讨基坑坡体监测位移矢量角与基坑安全性的关系。具体内容如下： 1、从动力学角度分析了在基坑坡体演化破坏过程中仅依赖位移或位移速率这一单一信息的缺陷性,并阐述位移矢量角的研究意义及其动力学特征,介绍了基坑坡体表面位移矢量角的基本构成及演化特征。 2、提出三条基坑坡体稳定性判据：(1)在基坑坡底位移矢量角将突然变小；在基坑坡顶位移矢量角将突然变大,在中间部分位移矢量角随时间将逐渐增大；(2)根据数理统计基本原理,对基坑坡体位移矢量角的异常变化是否为突变可采用均方差做判据,即位移矢量角变化值是否在其均值加均方差的倍数范围内波动作为边坡位移矢量角异常变化判据；(3)对于基坑坡底位移矢量角减小突变的最小值应与基坑坡体的倾角进行对比,如果大于坡体倾角,说明基坑土体下滑移动在其抗剪强度范围内,无剪出破坏的可能性,如果小于坡体倾角,说明基坑土体有向基坑以外运动,有剪出坡体发生失稳的趋势。 3、根据土钉支护的作用机理,将土钉与基坑坡体的土体组合起到骨架作用,从而提高土体的整体刚度和结构整体性,且指出土钉支护属于被动制约机制。 4、考虑基坑坡体在无支护和土钉支护条件两种情况时位移矢量角演化过程的变化规律,提出并验证位移矢量角在基坑坡体稳定性中的判据。 5、根据位移矢量角在简单土质条件下对基坑边坡稳定性的判据,进而探讨极端降雨产生渗流对土钉支护条件下基坑坡体安全性的影响,并将土钉支护与无支护条件下基坑坡体稳定性的预测预报及防治评价用做判据。
[Abstract]:Based on the project of National Natural Science Foundation of China and Shandong Province Natural Science Outstanding Youth Foundation, this paper has carried out the research and analysis of the numerical calculation of the slope safety of foundation pit, according to the deformation characteristics of soil. By using the nonlinear finite element method, the relationship between the displacement vector angle of slope monitoring and the safety of foundation pit is discussed by analyzing the results of numerical simulation. 1. From the dynamic point of view, the defect of the single information of displacement or displacement rate in the evolution and failure process of foundation pit slope is analyzed, and the significance of the study of displacement vector angle and its dynamic characteristics are expounded. The basic structure and evolution characteristics of displacement vector angle on slope surface of foundation pit are introduced. 2. Three slope stability criteria: 1) the displacement vector angle at the bottom of the foundation pit will suddenly become smaller, and the displacement vector angle at the top of the foundation pit will suddenly become larger, and the displacement vector angle in the middle part will gradually increase with time.) according to the basic principle of mathematical statistics, If the abnormal change of displacement vector angle of foundation pit slope is abrupt, the mean square deviation can be used as criterion. That is, whether the variation value of displacement vector angle fluctuates in the multiple range of mean value plus mean variance as the criterion of abnormal variation of slope displacement vector angle, the minimum value of reducing abrupt change of displacement vector angle at the bottom of foundation pit should be compared with the slope slope angle of foundation pit. If the slope angle is greater than the slope slope angle, it shows that the sliding movement of the foundation pit soil is within the range of its shear strength and there is no possibility of shearing failure. If the slope slope angle is smaller than the slope body inclination angle, it shows that the foundation pit soil is moving outside the foundation pit and has the tendency of instability of the shear out slope body. 3. According to the mechanism of soil nailing support, the combination of soil nailing and foundation pit slope body plays a skeleton role, thus improving the overall stiffness and structural integrity of soil, and pointing out that soil nailing support belongs to passive restraint mechanism. 4. Considering the evolution law of displacement vector angle in the condition of no support and soil nailing support, the criterion of displacement vector angle in the stability of foundation pit slope is proposed and verified. 5. According to the criterion of displacement vector angle to the slope stability of foundation pit under simple soil condition, the influence of percolation caused by extreme rainfall on the safety of foundation pit slope under soil nailing support is discussed. The prediction, prediction and prevention evaluation of slope stability of foundation pit under the condition of soil nailing support and no support are used as criteria.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU470

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