锚板在粘土中极限承载力的数值确定方法

发布时间：2018-05-02 11:15

本文选题：锚板 + 粘土　；参考：《天津大学》2014年硕士论文

【摘要】：极限承载力是描述锚板工作性能的一项重要参数,而一个确定的、统一的锚板极限承载力确定方法是获得可靠数据的前提,也是进行对比分析的前提。目前国内外研究者对锚板极限承载力的确定尚未有统一的方法,且已有的方法大多存在一定的不确定性和主观性。本文调研收集了以往研究者的确定方法,通过系统对比分析,推荐以锚板完整上拔过程中最大载荷作为极限承载力,并结合大变形有限元数值技术,研究锚板极限承载力。本文主要工作包括:首先,分析了两类典型的物理实验曲线和数值计算曲线。发现在试验中,随着位移增大,载荷先增大后减小,而基于小变形有限元数值技术的计算结果无法合理反映这一现象,因此本文推荐应用大变形有限元数值技术计算锚板完整拔出过程。目前主要有3类大变形数值分析技术:网格重划分法,任意的拉格朗日-欧拉法(Arbitrary Lagrangian-Eulerian method,ALE),和耦合的欧拉-拉格朗日法(Coupled Eulerian-Lagrangian method,CEL)。通过对比,认为CEL法较其它2种方法有克服网格畸变能力强、应用方便的优点,因此本文采用CEL法进行大变形计算。其次,采用已有的10种不同锚板极限承载力确定方法对两类典型的数值结果曲线进行量化分析,指出各种方法的不足之处:不确定性、不唯一性和主观性。结合物理实验曲线,推荐使用最大载荷法作为锚板极限承载力确定方法。再次,采用基于CEL法的大变形有限元数值技术研究方形锚板在均质土及线性土中的承载力,以及圆形锚板在线性土中的极限承载力。通过与试验结果对比,验证了CEL方法的有效性;在分析线性土中锚板的承载力时,通过用户自定义子程序,实现了线性土强度分布随锚板拔出的变化;通过与试验对比线性土中锚板上拔至泥面过程中完整的位移-载荷曲线,体现了CEL法模拟锚板在大位移条件下载荷响应的出色能力。最后,将本文提出的锚板极限承载力确定方法结合基于CEL法的大变形有限元技术应用于不同形状锚板在无重均质土及无重线性土的极限承载力分析。结果表明:随着矩形锚板长宽比增大,锚板极限承载力降低,临界埋深增大;锚板在均质土中的极限承载力普遍比线性土中要高;长宽比大于6的矩形锚板可视作条形锚板;圆形锚板极限承载力比方形锚板极限承载力稍高。
[Abstract]:Ultimate bearing capacity is an important parameter to describe the working performance of anchor plate, and a definite and unified method of determining ultimate bearing capacity of anchor plate is the premise to obtain reliable data and to carry out comparative analysis. At present, researchers at home and abroad do not have a unified method to determine the ultimate bearing capacity of anchor plates, and most of the existing methods are uncertain and subjective. Through systematic comparison and analysis, it is recommended that the maximum load in the whole uplift process of anchor plate should be taken as the ultimate bearing capacity, and the ultimate bearing capacity of anchor plate should be studied by combining the finite element numerical technique of large deformation. The main work of this paper is as follows: firstly, two kinds of typical physical experimental curves and numerical calculation curves are analyzed. It is found that the load increases first and then decreases with the increase of displacement, but the calculation results based on the finite element technique of small deformation can not reasonably reflect this phenomenon. Therefore, it is recommended that the large deformation finite element numerical technique be used to calculate the complete pullout process of the anchor plate. At present, there are three kinds of large deformation numerical analysis techniques: grid redivision method, arbitrary Lagrangian Euler method arbitrary Lagrangian-Eulerian method, and coupled Euler-Lagrangian method and coupled Eulerian-Lagrangian method. Compared with the other two methods, the CEL method has the advantages of strong ability to overcome the grid distortion and convenient application. Therefore, the CEL method is used to calculate the large deformation in this paper. Secondly, ten existing methods for determining ultimate bearing capacity of anchor plates are used to quantitatively analyze two typical numerical result curves, and the shortcomings of these methods are pointed out: uncertainty, non-uniqueness and subjectivity. Combined with the physical experimental curve, the maximum load method is recommended as the method to determine the ultimate bearing capacity of the anchor plate. Thirdly, the bearing capacity of square anchor plate in homogeneous soil and linear soil and the ultimate bearing capacity of circular anchor plate in linear soil are studied by using large deformation finite element method based on CEL method. The validity of the CEL method is verified by comparing with the test results, and the variation of the strength distribution of the linear soil with the pulling out of the anchor plate is realized by the user-defined subroutine in the analysis of the bearing capacity of the anchor plate in the linear soil. By comparing the complete displacement-load curve between the anchor plate and the mud surface in the linear soil, the excellent ability of the CEL method to simulate the load response of the anchor plate under the condition of large displacement is demonstrated. Finally, the method of determining the ultimate bearing capacity of anchor plate proposed in this paper is applied to the analysis of ultimate bearing capacity of different shape anchor plates in weightless homogeneous soil and weightless linear soil with large deformation finite element method based on CEL method. The results show that with the increase of the ratio of length to width of rectangular anchor plate, the ultimate bearing capacity of anchor plate decreases and the critical buried depth increases, the ultimate bearing capacity of anchor plate in homogeneous soil is generally higher than that in linear soil, and the rectangular anchor plate with ratio of length to width greater than 6 can be regarded as strip anchor plate. The ultimate bearing capacity of circular anchor plate is slightly higher than that of square anchor plate.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU442;TU476

【参考文献】