【作者】 王向东；

【导师】 徐道远；

【作者基本信息】 河海大学 ， 水工结构， 2004， 博士

【摘要】 混凝土大坝等混凝土结构在各种外界因素的作用下，材料会产生损伤，因此结构处于一个损伤场中，且损伤在外界因素的作用下将会进一步发展，如果按无损情况来分析计算，显然与结构的实际情况会有一定的差异，因此在结构的分析中必须考虑材料的损伤特性才能得到结构的真实力学响应和工作性态。 因此，混凝土损伤力学已日益受到的人们的重视。本论文在徐道远教授为首的河海大学断裂与损伤课题组研究成果的基础上，对混凝土的损伤理论和工程应用中的若干问题进行了研究， 通过对混凝土材料的破坏机理分析，认为混凝土体从受外荷载（或其它外界因素）作用起，直至破坏的过程，就是一个在初始损伤的基础上，损伤发展和积累的过程。本文用损伤描述了混凝土的应力应变软化效应及混凝土破坏过程中断裂与损伤的交织行为，揭示了混凝土破坏机理的实质。 提出了三种混凝土损伤定量计算的方法，同时还得到了推算无损混凝土弹性模量和强度的方法。由于混凝土材料的拉、压性质不同，所以也进行了与定量分析有关的混凝土拉、压损伤定量转换关系的研究。得出了在绝对值相同应变情况下，拉、压损伤定量转换公式。 设计了一套测试方案，以加引气剂模拟初始损伤的方法，用可实现的轴向拉、压等试验所测得的弹性模量，再根据损伤理论，得出了混凝土的初始损伤D₀和损伤阈值Df。 分析了混凝土的损伤参数作为材料参数也具有尺寸效应，并对混凝土损伤参数的尺寸效应问题进行了研究，导出了将小尺寸试件测得的损伤参数D₀和D_f转换为实际大尺寸结构损伤参数的关系式。并对普通混凝土给出了一些大尺寸试件的D₀和D_f的参考值。 讨论了将损伤反映到损伤有限元支配方程中的方法，得到了混凝土损伤场有限元计算的方程。据此可以进行混凝土结构随荷载变化的损伤仿真计算。 分析了进行混凝土大坝的损伤仿真有限元分析的方法，推导了损伤仿真有限元方程。并对某大坝进行了损伤仿真计算，得到了损伤场随时间的变化规律，并用损伤理论对其作了分析。从计算结果看出，混凝土大坝损伤场随时间的变化规律与应力随时间的变化规律有所不同，损伤场才能够更有效的反映结构的工作性态，方能正确地估计其使用寿命，因此有力地证明了损伤仿真计算的必要性和重要性。更多还原

【Abstract】 Under the load of some outer factors, there exists damage inside the concrete-structure, i.e., the concrete-structure is in a damage-field, and meanwhile the damage will develop further. It is unreliable to analyze on the concrete structures under the condition of non-damage. So, it is necessary and important to analyze the damage of the concrete-structures, so as to know the real mechanics or responding of the structures.So, it’s important to pay more attention to the Concrete Damage Mechanics. Being based on the results researched by the Concrete Fracture and Damage Group of Hohai University, which is led by professor Xu Daoyuan, this paper studies on the application of Concrete Damage Mechanics in the damage simulation of hydraulic structures.After we analyze on the rupture mechanism of concrete material, the whole progress from the initial damage to the final damage inside the structure of concrete under the outer load or other outer factors is just a progress that the damage is formed and developed further. Using Damage Mechanics, it has been described that the stress-strain softening and the interweaving between the damage and fracture during the rupture of concrete.This paper presents three quantitative analyses of concrete damage and the method how to calculate the undamaged elastic modulus and undamaged strength. Because of the different properties when concrete is tensed and compressed, the translation relation of the tension damage and compression damage has been studied. The translation equation of the tension damage and compression damage cased by the same absolute value strain has been gained.An experimentation method has been designed, which can simulate the initial damage by mixed initiator into concrete. Using the elastic modulus of axial tension and compression experimentation, the initial damage D0 and damage threshold value Dfhave been gained.The size effect of concrete damage coefficient such as the initial damage D0 and damage threshold value Df has been studied. The translation relation of damage coefficient between the small and large specimens has been gained.The equation of damage finite element has been gained. The damage simulation calculation varied with load of concrete structure can be realized.After analysis on the method of the damage simulation, we have obtained the three dimensions’ finite element equation of damage simulation. The damage simulation calculation of an arch dam has been calculated. The regular that the damage field varies with time gained in this paper are analyzed with concrete damage theory. Being based on the final results, the regular that damage change with time is different from one stress with time. So, this kind of damage-field may show correctly the work property of the concrete-structure. Finally, the usage age of dam can be estimated. So, we can say that the damage simulation calculation is very important and necessary.更多还原