高拱坝关键区域局部破损分析

发布时间：2019-02-16 06:47

【摘要】：高拱坝作为一种复杂的混凝土结构,坝踵、坝趾及基础内断层错动带均为可能发生破坏的区域,且多个破坏区域可能同时存在。结构发生失稳是一种由局部破坏到整体失稳的行为。此问题涉及两个方面,即如何确定发生局部破坏的位置以及局部破坏是以何种方式发展的。本文的主要的研究成果如下:(1)提出一种对高拱坝关键区域的破坏模式分析的方法。此方法将变形加固理论和子模型方法联合运用。首先运用变形加固理论确定影响高拱坝稳定的关键区域,在对这些关键区域划分子模型,进行局部破损模式的精细分析,并将这种分析方法运用到白鹤滩高拱坝的数值模型模拟中。对白鹤滩拱坝进行了整体稳定分析、坝踵区不平衡力分析以及基岩内断层的稳定性分析,在此基础上确定拱坝坝踵以及基础的可能破坏位置,对坝踵及基岩断层划分子模型,进行精细的破坏模式的讨论。(2)发展了基于格构模型和有限元耦合的裂纹开裂模拟方法。可以将有限元网格自动转化为格构模型,这样即利用了有限元在常规计算中的高效性,也利用了格构模型在处理开裂区域的方便性。在初始计算模型中可以不对开裂区域进行特殊指定,开裂部分为有限元计算应力超过材料的抗拉强度的区域,将此区域转化为格构模型并作相应的处理即可模拟结构的开裂和裂纹扩展。同时,将此方法用于模拟多裂隙体的等效弹性模量。(3)进行了锚索对边坡体的锚固效果的分析。将锚索的锚固效果分为预应力和抗变形能力两部分,将预应力转化为锚固区域的平均预压力施加在边坡体上,抗变形能力则是通过将锚索(杆)刚度加入整体刚度矩阵得以实现。对一边坡模型做降强计算,得到其塑性余能、不平衡力以及边坡表面变形随超载倍数的变化。比较后得到,塑性余能对边坡是否加锚反应很敏感,其次是不平衡力,而边坡表面变形对边坡是否加锚反应不敏感。(4)在以内变量描述的热力学基础上对弹塑性材料临界点的稳定性进行了讨论,材料在临界点附近的行为仅与材料本身的自由能函数的几何结构有关。同时,在热力学基础上对Drucker公设和Ilyushin公设进行了讨论,得出热力学定义中的两个公设的统一表达。
[Abstract]:As a kind of complex concrete structure, high arch dam, dam heel, dam toe and fault dislocation zone within foundation are all areas where failure may occur, and many failure regions may exist simultaneously. Structural instability is a kind of behavior from local failure to global instability. This problem involves two aspects, that is, how to determine the location of local failure and how the local failure develops. The main results of this paper are as follows: (1) A method for analyzing the failure modes of high arch dams is proposed. This method combines deformation reinforcement theory with submodel method. Firstly, the key areas which affect the stability of high arch dams are determined by the deformation reinforcement theory, and the local damage modes are analyzed in detail by submodels of these key areas. The method is applied to the numerical simulation of Baihetan high arch dam. The overall stability analysis of Baihetan arch dam, the analysis of unbalanced force in dam heel area and the stability analysis of fault in bedrock are carried out. On the basis of this, the location of failure of arch dam heel and foundation is determined, and the submodel of dam heel and bedrock fault is divided. The detailed failure mode is discussed. (2) the crack cracking simulation method based on lattice model and finite element coupling is developed. The finite element mesh can be automatically transformed into a lattice model, which makes use of the high efficiency of the finite element method in the conventional calculation and the convenience of the lattice model in dealing with the cracking area. In the initial calculation model, the crack region can not be specified, and the crack part is the area where the finite element calculation stress exceeds the tensile strength of the material. The crack and crack propagation of the structure can be simulated by transforming the region into a lattice model and corresponding treatment. At the same time, this method is used to simulate the equivalent elastic modulus of multi-fissure body. (3) the anchoring effect of anchor cable on slope is analyzed. The anchoring effect of Anchorage cable is divided into two parts: prestressing force and anti-deformation ability. The ability to resist deformation is realized by adding the stiffness of anchor cable (rod) to the whole stiffness matrix. The variation of plastic complementary energy, unbalance force and slope surface deformation with overload ratio is obtained by calculating the strength of a slope model. Compared with each other, the plastic residual energy is sensitive to whether the slope is anchored or not, followed by the unbalanced force. However, the surface deformation of the slope is insensitive to whether the slope is anchored or not. (4) the stability of the critical point of elastic-plastic material is discussed on the basis of thermodynamics described by internal variables. The behavior of the material near the critical point is only related to the geometric structure of the free energy function of the material itself. At the same time, the Drucker and Ilyushin postulates are discussed on the basis of thermodynamics, and the unified expression of the two postulates in the definition of thermodynamics is obtained.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TV642.4

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