【作者】 杜荣强；

【导师】 林皋；

【作者基本信息】 大连理工大学 ， 水工结构工程， 2006， 博士

【摘要】 本文针对混凝土损伤敏感性和率相关的动态特性，建立了考虑多轴损伤破坏的混凝土各向异性弹塑性损伤模型和能量基率相关动力损伤模型，并将建立的模型应用于200m级重力坝和300m级高拱坝静、动损伤响应分析和抗震安全评价。为反映混凝土损伤的单向效应特性和揭示其相应的拉、压破坏机理，对损伤进行了拉、压分离；对三个主方向按拉、压状态用三个不同的损伤破坏函数来表征其破坏准则，准则中反映了损伤量对混凝土拉、压强度和刚度的劣化作用。利用能量等效原理推导得到率相关动力损伤模型，模型可较全面地反映应变率对损伤演化的影响。应用于混凝土大坝的静、动损伤响应分析，得到的结果可解释大坝损伤模式和动力作用下的渐进破坏趋势或潜在破坏模式。结果表明，所建立的混凝土损伤模型可有效地进行高坝抗震安全评价。本文主要研究工作如下： 一方面，建立了不仅可描述多轴受压损伤破坏、而且还可考虑多轴拉伸损伤破坏的多轴损伤破坏准则，考虑损伤的各向异性特点，进一步建立了各向异性弹塑性损伤模型。该模型用于混凝土结构破坏分析可有效判断混凝土的拉伸和压缩破坏，而对实际大坝而言，由于采用了较高的抗压安全系数，建立拉伸破坏准则的工作将更有意义，因为这对混凝土大坝的安全更为不利。 由于单轴损伤演化方程难以准确度量多轴应力状态下的损伤程度，本文引入了多轴破坏准则对应的破坏面，建立了反映当前应力状态的三轴影响因子，基于符合混凝土实际变形和破坏特点的单轴损伤演化方程，建立了混凝土多轴损伤演化方程，从而解决了多轴情况下的损伤度量问题。进而将所得到的损伤主量应用于多轴弹塑性损伤破坏准则中的对应方向，以分别反映对拉、压强度和刚度劣化的影响。 另一方面，针对混凝土动态特性对损伤的影响，基于能量等效原理推导得到了动力损伤模型，该模型较全面地反映了应变率在损伤演化中的影响，包含了软化阶段和硬化阶段有损伤演化的情况；同时对李庆斌根据不同应变率下混凝土动、静应力—应变全曲线具有几何相似特点推导得到的动力损伤模型做了讨论。对这两种动力损伤模型应用于混凝土大坝的静、动损伤响应分析并进行了量化比较。应用于Koyna坝的静、动损伤响应分析结果和大坝的实际震害情况比较相符；研究发现，在地震作用过程中利用损伤指标判定结构的损伤破坏要比用应力指标清晰和明显，因为应力指标随地震作用会有波动，而用损伤作为内变量累积则能体现大坝抗震薄弱部位的损伤发展和渐进破坏进程。进一步比较了率无关、率相关损伤模型对大坝地震损伤响应的影响。然后，分析了高重更多还原

【Abstract】 Anisotropic elastoplastic damage model with multiple damage failure criteria (MDFC) and rate-dependent damage model for concrete correlating with damage sensitive and rate-dependent of concrete are constructed. The models are used to analyze damage response for 200m grade concrete gravity dams and 300m grade arch dams under static overflow, earthquake and dam safety assessment resisting earthquake. Damage variable is split into tensile and compressive components to depict concrete failure due to tension or compression and to be used to analyze unilaterial effect under cyclic loading in concrete damage theory. With the splitting, different failure mechanism from tension or compression can be found in the process of concrete failure. The MDFC with three different damage failure functions expressed by effective stresses is improved from multiple plastic failure criteria. Rate-dependent damage evolution equation (RDEE) is educed with the principle of energy equivalent in damage mechanics theory and references of concrete dynamic experiments. The potential failure or progressive failure patterns of the dams under overflow loads or earthquake can be simulated numerically with the models through damage responses. Responses of the dams with the suggested model show the model and damage mechanics method are effective tools to numerical analysis and damage safety assessment for dams under earthquake.On the one hand, the MDFC with three different damage-plastic failure functions is suggested, which can not only deal with failure from compressive damage, tensile damage degradation under related axes but also consider anisotropic characteristic for damage. Furthermore, anisotropic damage failure criteria is proposed. Tensile and compressive damage variables together with elastoplastic damage under tension and compression are considered. And the latter is paid more attention to because it is more disadvantageous to the safety of dams.The damage variables used in the criteria are achieved from damage evolution equation considering multiple failure condition. Most concrete structures work under biaxial or triaxial stress state, which have different stress-strain relationships from the uniaxial one, especially at the stage of strain softening. The damage evolution equation accompanying with the constitutive relationship of multiaxial stresses (multiple damage evolution equation, shorting for MDEE) is improved from that of uniaxial stress state (UDEE). A multiaxial effective更多还原