【作者】 徐俊祥；

【导师】 朱为玄；

【作者基本信息】 河海大学 ， 工程力学， 2004， 硕士

【摘要】 在实际工程中使用的材料或构件及结构是存在初始损伤的，其从开始变形直至破坏，是一个逐渐劣化的过程，在这个过程中，微裂纹的聚合和长大造成了宏观裂纹的形成和发展。而应运而生的损伤力学恰是研究材料内部微观缺陷的产生和发展所引起的宏观力学效应及最终导致材料破坏的过程和规律的一门学科。 在土木工程结构中，混凝土是一种被广泛采用的材料，其在浇筑成型过程中也不可避免的会有初始损伤存在，这些初始损伤在外载的作用下会不断的演化发展。为了对混凝土结构进行损伤力学的计算分析，本文通过混凝土试件的拉伸和压缩试验，利用损伤力学的理论，对混凝土结构的初始损伤进行了分析，得出了具有一定参考价值的初始损伤值及峰值应力对应的损伤值，其对于混凝土损伤模型的建立及该模型在工程中的应用具有一定的意义。另外，混凝土损伤破坏准则的建立对于损伤力学在混凝土结构中的应用也具有重要的作用，为此，本文中将损伤变量引入了Drucker-Prager准则，此外，还根据损伤的能量释放率定义对损伤的破坏准则进行了初步的探讨。 本文将上述试验确定的混凝土的初始损伤值及损伤阈值引入河海大学徐道远教授提出的指数函数损伤模型，根据损伤问题的初边值条件，建立了含损伤的有限元方程，并基于大型通用有限元软件Marc编制了损伤计算程序，通过算例进行了程序的验证，使得对混凝土结构的损伤模拟成为了可能，为损伤力学在土木工程中的应用进行了有益的探索。 当混凝土结构在外载作用下进入损伤破坏阶段后，在本文内认为当混凝土结构内的损伤达到损伤阈值后，在结构内部将会产生微裂纹，由于这些裂缝的存在，使得混凝土结构的损伤分析变得异常困难，为此本文以抹平式裂纹模型为基础，引入指数函数损伤模型，以调整单元刚度的方法考虑裂纹和损伤的影响，建立了混凝土结构损伤破坏分析的数值方法，并进行了算例分析，取得了较好的结果。 本文最后利用上述的混凝土损伤分析方法，以索风营水电站大坝为工程背景对其进行了损伤力学分析，得出了合理的结果。更多还原

【Abstract】 The material or structure used in practical engineering away have initial damage which gradually devepop from beginning of distortion to failure, in this process polymerization and development of micro-cracks will cause formation and expand of macro-cracks. The damage mechanics is just a science that study the process and law of the material’s destroy caused by microbug.In civil engineering, concrete as a sweeping adopted material inevitably have initial damages during construction .which will further evolve and develop under exterior loads. In this paper, in order to carry out damage analysis of concrete structure , concrete’s initial damage and damage threshold value that is some significant to the establishing of concrete damage model are studied through the stretch and compress experimentation of concrete .In addition ,in view of significant of concrete damage failure in analysis of structure, in this paper rule of concrete damage failure based on both definition of damage energy release rate and Drucker-Prager rule are also discussed.Concrete’s initial damage and damage threshold value gained through above experimentation is imported to exponent function damage model advanced by professor Xu Dao-yuan , and finite element equation included influence of damage is derivated .Based on great current finite element program-Marc , damage compute program is worked out and testified through examples. This make damage compute possible and is significant explore for damage mechanics’s application to civil engineering.In this paper the author assume that micro-cracks will occur in the concrete structure after damage threshold value is reached. Because of existence of micro-cracks, it is very difficulty for us to analysis concrete’s damage. The numerical method for analysis of damage failure is put forward through combination model of exponent function damage with model of smeared crack model. The example computed in the chart show that the method is reasonable .Finally ,the damage analysis of Suofengying dam is carried out ,and reasonable results are gained.更多还原