【作者】 刘君；

【导师】 马震岳； 沈成能；

【作者基本信息】 大连理工大学 ， 水利水电工程， 2005， 硕士

【摘要】 对于混凝土重力坝的抗滑稳定性分析,由于地基内岩石节理、软弱夹层及断层等不连续结构面的存在,给有限元模型的建立和有限元分析带来了极大的困难,对它的处理是计算中一个重要而又困难的问题,这是本文选题的基本出发点。而这一问题实际属于对弹塑性接触问题的求解,因而建立重力坝三维有限元接触模型并将其应用于重力坝深层抗滑稳定分析成为本文的主要研究内容。本文以ANSYS为操作平台,以弹塑性有限元基本理论和接触问题有限元基本理论为基础,建立了重力坝三维有限元接触模型。模型的核心是以三维实体单元模拟断层或软弱夹层材料弹塑性变形特性,以接触面单元模拟断层或软弱夹层与完整岩石之间交界面的力学特性,即剪切效应和法向提离效应,从而实现了弹塑性问题和接触问题的耦合。在三维有限元接触模型具体实现的论述中,重点讨论了接触面单元的选择和单元实常数设置以及摩擦问题的简化处理,并探讨了接触问题实常数FTOLN(最大穿透范围)、FKN(法向接触刚度因子)的选择对含有软弱夹层的复杂地基体系分析的影响,确定了FTOLN和FKN的合理取值。根据所建立起来的三维有限元接触模型,对云峰宽缝重力坝51#和52#坝段整体抗滑稳定性进行了三维有限元分析,其抗滑稳定性和变形分析成果证明该三维有限元接触模型是合理的、可信的。另外,针对有限元法缺乏配套的设计标准问题,在分项系数法和可靠度思想的基础上,提出了分项系数有限元法。较之于基于经验的传统的安全系数法,该方法在结构安全度的判断上更加合理,为有限元法在抗滑稳定分析中的应用和发展创造了良好条件。更多还原

【Abstract】 Discontinuous constructions such as joints, weak interlayers, and faults are prevalent in the foundation, which causes great difficulty for establishing FEM-model and conducting FEM analysis. It is therefore an important and hard problem to be solved during computation. It is actually one of the solutions to contact problems. That is the basic point from which this paper selects the theme. So establishing 3D FEM-contact-model for gravity dam and putting it into actual analysis on deep anti-sliding stability is the main topic the paper explains about.In this paper, the establishment of 3D FEM-contact model is based on elastoplasticity FEM theory and contact FEM related theory on ANSYS operating platform. The core of this model is using solid element to simulate elastoplasticity deformation of faultage and using contact element to simulate the interface of faultage and rock, and so, realizing the problems coupling of elastoplasticity and contact.In discussion on the actual application of contact analysis to ANSYS, the paper focuses its discussion on the selection of contact element, configuration of true constants, and the simplified treatment of friction matters. Besides, it also discusses what the selection of true constants for FTOLN and FKN will affect the analysis on complicated foundation system that contains weak interlayers, defines the values for FTOLN and FKN.Based on the established 3D FEM-contact-model, it is analyzed that the deep anti-sliding stability and deformation for the whole 51# and 52# sections at Yunfeng Slotted Gravity Dam. By the results of analysis and comparison, it proves sufficiently that this FEM-contact-model for gravity dam is accurate, rational and credible.Furtherly, in allusion to the absence of design standard in FEM, basing subency coefficient and reliability idea, it puts forward subentry coefficiet FEM method. This method is more rational than tradional safety factor method in the judging of degree of sagety of structure.更多还原