【作者】 张娟霞；

【导师】 唐春安；

【作者基本信息】 东北大学 ， 采矿工程， 2006， 博士

【摘要】 混凝土材料结构的破坏过程，是一个极其复杂极富挑战的研究课题，一直是力学、材料和工程等各学科的研究热点和难点之一。研究混凝土结构的破坏过程，对揭示混凝土结构破坏过程的宏观非线性力学行为本质及其破坏机理，评价混凝土结构以及混凝土结构工程的安全状态，都具有重要的理论意义和工程实用价值。 实验室试验和现场测试作为研究混凝土结构破坏过程最为直接的手段，为促进其破坏过程的研究发展起了决定性作用。然而，由于受人力、物力、财力等因素的制约，试验和现场测试工作往往受到限制。理论解析通过对材料进行简化，运用数学和力学等研究方法，对其破坏过程的应力与应变关系及诱发的声发射等进行解析，为研究混凝土结构破坏过程提供了重要途径。然而，限于目前数学、力学等的发展水平，解析方法还难以解析混凝土材料内部微破裂之间以及由于非均匀性而引起的局部破坏。数值方法为研究混凝土结构的破坏过程提供了重要手段。除少数的混凝土力学问题可以简化为平面问题外，二维模型的应用是有限的，大多混凝土结构的破坏问题是三维的力学问题，需要采用三维破坏过程分析工具进行研究。由于混凝土材料非均匀性的存在，很容易产生不对称破坏，此时二维破坏问题就变成了三维破坏问题。 本文首先从混凝土材料的非均匀性出发，采用Weibull随机统计分布理论引入材料的非均匀性，在考虑细观单元非均匀性的基础上，建立了三维弹性损伤演化本构模型，通过非均匀介质变形过程中微破裂积累造成的力学性质弱化来反映混凝土宏观变形非线性的本质特征。为研究混凝土材料结构的破坏过程提供了力学理论基础；此外，计算机硬件及计算力学的飞速发展，为从细观结构层次上研究混凝土等固体材料的破坏过程提供了强有力的数值计算工具。 其次，通过对钢筋混凝土杆件在轴向拉伸作用下破坏过程的数值模拟，得到破坏过程中所出现的等间距裂缝现象，并通过对二裂缝间的应力进行分析，探讨了等间距裂缝产生的机理，所得的结果与前人的理论分析结果相一致，并通过对轴向受拉构件二裂缝之间间距理论公式的推导，得出影响裂缝间距的因素，并通过三维材料破坏过程分析系统对此影响参数进行了分析研究，得出影响裂缝间距及裂缝数目及分布规律的因素，在此基础上，又分析了材料的不同力学参数等对构件在轴向拉伸作用下破坏时裂缝产生的数目及裂缝间距的影响。并模拟分析了不同混凝土保护层厚度构件的破坏过程及对钢筋的受拉刚化作用的影响。更多还原

【Abstract】 The complex deformation and failure process of concrete structure is a great challenge for many researchers from engineering mechanics and materials science to devote them to it. It is prone to study the no-linear mechanics behavior nature and the failure mechanics, estimate the safe state of the concrete structure engineering. So it is of great importance and significance to investigate the deformation and failure process of concrete structures.Laboratorial tests and in-situ observations have been an effective and direct waysof studying the failure process of concrete structures failure, and these ways play acrucial role in the study of material failure process. But because of the limitation ofthe resource on the manpower, substance, finance, so there is some limitation on thelaboratorial tests and in-situ observations. Analytical method such as mathematics andengineering mechanics is also important in investigating the stress-strain relation andthe induced acoustic emission by some simplifications to materials. However, themathematical and mechanical methods are seemed to be weak in dealing with thecomplex interactions among micro-cracks and the local failure due to theheterogeneities. As a result, numerical method, a most widely used and effectivemethod, can serve as a tool to study the failure process of concrete structure. Theproblems in concrete failure mechanics and engineering are of three-dimension tosome extent. Many concrete mechanical problems, except plain strain problems andplain stress problems are also related to many directions and cannot be simplified totwo-dimension due to the heterogeneities of the materials.Firstly, based on the microscopic structures and constitutive relation of concrete on a meso-level, the whole failure process of concrete structure can be solved combined with computational mechanics and statistics. Stochastic functions, including Weibull distribution function, by introducing heterogeneity of mechanical properties of materials into the model, MFPA3D can simulate non-linear deformability of a quasi-brittle of ductile failure behavior with a simple constitutive law for the local material. By introducing a reduction of material parameters after element failure, it can simulate strain-softening and discontinuum mechanics problems in a continuum mechanics mode. In addition, the quick development of computer hardware and computational mechanics make it a powerful tool to更多还原