建筑学论文蜗壳外围混凝土裂缝稳定性分析.doc

蜗壳外围混凝土裂缝稳定性分析 蜗壳外围混凝土裂缝稳定性分析 Stability Analysis for the Surrounding Concrete Cracks of Spiral Case【中文摘要】 直埋式蜗壳由于钢衬与混凝土直接接触,在内水压力作用下蜗壳外围混凝土会不同程度的出现裂缝,而在动态水击压力、最大内水压力和检修放空等各种工况下,蜗壳结构受力条件更趋复杂,因此对蜗壳外围混凝土裂缝的稳定性进行研究就十分必要。而现有的大量研究成果尚缺乏基于断裂力学的分析,对蜗壳外围混凝土裂缝稳定性的研究也相对较少。针对这个问题,本文以通用有限元软件ANSYS为平台,通过建立有限元模型,引入混凝土断裂力学,对蜗壳外围混凝土裂缝的稳定性进行了计算分析,本文主要做了以下几方面的工作:(1)取蜗壳进口段,建立周期对称管节模型,进行了非线性计算分析,得到了蜗壳外围混凝土的裂缝分布范围和裂缝宽度。(2)对外围混凝土裂缝进行概化,建立了带裂缝的有限元模型。引入混凝土断裂力学,计算了裂缝在各种荷载下的缝端应力强度因子。根据混凝土复合裂缝断裂判据对裂缝的稳定性进行判断。(3)考虑了温度变化对蜗壳外围混凝土裂缝的稳定性影响,计算了最大温升和最大温降工况下蜗壳外围混凝土裂缝的应力强度因子。根据混凝土复合裂缝断裂判据对裂缝在考虑温度作用后的稳定性。(4)采用ANSYS中的非线性弹簧单元模拟了钢筋混凝土之间的粘结滑移作用,建立了考虑粘结滑移作用的有限元模型,计算分析了钢筋混凝土粘结滑移对蜗壳外围混凝土裂缝的稳定性影响。本文在建模及计算过程中尽可能真实的模拟直埋蜗壳结构的实际工作状况,通过数值计算得出一些有益结论,为实际工程提供了一定的参考价值。【英文摘要】 Because of direct contact between steel lining and surrounding concrete,some cracks would be appear in the surrounding concrete of complete beating spiral case under the internal water pressure.If considering the pulsation pressure,maximal internal water pressure and other special conditions.the strainedcondition of spiral case could be more complex.So the research for stability analysis of surrounding concrete cracks of spiral case is very necessarily.There is lack of existing research results based on fracture mechanics and there are very few of research on stability of cracks of concrete of spiral case.Focused on this question,a 3D-nolinear simulation model has been established to calculate the stress intensive factor and analysis the stability of concrete cracks of complete beating spiral case.The following aspects are studied:(1) Using the cycle symmetry method,the FEM section model of has been established and a non-linear finite element analysis has been carded on to anslyze the complete beating spiral case.The distribution of cracks in concrete outside the spiral case could be given.(2) The FEM model of spiral ease with cracks has been established based on the generalized for cracks.The stress intensive factor of concrete cracks under some load conditions has been calculated and the stability analysis of concrete cracks has also been completed based on concrete mixed cracks criterion.(3) Considering the influence to stability of concrete cracks by temperature change,the stress intensive factor of concrete cracks has been calculated under the maximum temperature rise condition and maximum temperature drop condition.The stability of cracks in concrete outside the spiral case has also been completed based on concrete mixed cracks criterion.(4) Using the non-linear spring element in ANSYS to simulate the bond-slip between reinforced and concrete,the FEM model with bond-slip has been established.The stress intensive factor of concrete cracks has been calculated and the stability analysis of concrete cracks has also been completed based on concrete mixed cracks criterion.During the modeling and calculating,the simulation of structure is as accurate as possible to reflect the characteristic of real engineering.As a result,some useful conclusions are drawn and can be referred to the real project.【中文关键词】 蜗壳裂缝; 断裂力学; 应力强度因子; 粘结滑移 【英文关键词】 Concrete Crack; Fracture Mechanics; Stress Intensive Factor; Bond-slip 【论文目录】摘要 4-5 Abstract 5 1 绪论 10-16 1.1 论文研究背景 10-11 1.2 蜗壳结构形式及其特点 11-12 1.2.1 垫层蜗壳 11-12 1.2.2 保压蜗壳 12 1.2.3 直埋式蜗壳 12 1.3 蜗壳外围混凝土裂缝研究现状及存在问题 12-15 1.3.1 蜗壳外围混凝土裂缝分布特点 12-13 1.3.2 蜗壳外围混凝土裂缝研究方法及研究现状 13-14 1.3.3 蜗壳外围混凝土裂缝研究存在的主要问题 14-15 1.4 本文研究内容 15-16 2 研究的理论基础和方法 16-30 2.1 混凝土断裂力学 16-24 2.1.1 混凝土断裂力学的产生和发展 16-17 2.1.2 混凝土断裂力学的分类 17-20 2.1.3 混凝土断裂判据 20-21 2.1.4 混凝土断裂力学的应用方向 21 2.1.5 ANSYS中求解断裂参量的理论方法 21-24 2.2 周期对称结构有限元分析 24-26 2.3 接触问题有限元基本原理 26-30 2.3.1 接触问题 26-27 2.3.2 接触问题有限元求解方法 27-29 2.3.3 ANSYS接触单元 29-30 3 蜗壳外围混凝土裂缝稳定性分析 30-46 3.1 研究思路 30 3.2 蜗壳外围混凝土非线性分析 30-37 3.2.1 计算范围 30-31 3.2.2 计算模型 31-33 3.2.3 材料特性 33-34 3.2.4 边界条件与荷载分布 34 3.2.5 计算结果与分析 34-37 3.3 蜗壳外围混凝土裂缝稳定性分析 37-45 3.3.1 计算模型 37-38 3.3.2 材料参数、边界条件和荷载工况 38-39 3.3.3 计算结果与分析 39-45 3.4 本章小结 45-46 4 温度作用下蜗壳外围混凝土裂缝稳定性分析 46-61 4.1 热传导理论简述 46-49 4.1.1 热传导方程的建立 46-48 4.1.2 求解热传导方程的初始条件和边界条件 48-49 4.2 影响混凝土温度场的因素 49-52 4.2.1 气温 49-50 4.2.2 库水温度 50-52 4.3 混凝土温度应力的发展过程 52 4.4 温度作用对蜗壳外围混凝土裂缝稳定性的影响 52-60 4.4.1 气候条件 52 4.4.2 计算模型及计算工况 52-56 4.4.3 计算结果及分析 56-60 4.5 本章小结 60-61 5 钢筋混凝土粘结滑移对裂缝稳定性的影响 61-