强震时超高面板坝面板破损机理及其抗震对策研究

A lot of 300m high concrete face rockfill dam have been constructed or being planned or designed in the southwestern region of China, where earthquake with high seismic intensity occurred frequently. The potential risk of seismic subsidence, slope sliding, slab fracture and even failure of the seepage control system will occur once the earthquake happened. So this study intends to establish an elastic-plastic damage progressive analysis method by developing the rockfill generalized plastic P-Z model, and integrating concrete elastic-plastic damage model and fluid-structure coupling analysis approach. Then the slab crack mode and failure mechanism will be studied after the researching of the slab dynamic response characteristics and patterns. Moreover, a new concept of high toughness composite slab will be proposed upon the aforementioned research results. The working principle and failure mechanism of the composite slab will be revealed by the laboratory test. The computational model for the composite slab will be constructed and the application range of this type material will be optimized. The influence of the permanent horizontal construction joint on the seismic stress and damage degree of the slab, as well as the working mechanism of the reinforcement between the slab and the cushion layer will also be studied. On these bases, a combined aseismic measure will be proposed, including the use of the high toughness composite slab, the permanent horizontal construction joints set up at the face-slab and the reinforced material located in cushion layer. After that, the influences of this measure on reducing the slab high stress and degree of damage will be evaluated, and the composite mechanism of this measure will also be studied.

我国西南地区正规划建设多个300m级超高面板堆石坝，而该地区地震活动频繁且烈度较高，一旦遭遇强震，将可能产生堆石体震陷、滑坡，进而导致面板破损、防渗功能丧失等严重灾害。本研究拟发展筑坝堆石料广义塑性本构模型，集成混凝土弹塑性损伤模型及库水-大坝流固耦合等分析技术，建立强震作用下超高面板坝弹塑性损伤渐进破坏分析方法。研究超高面板坝面板地震响应特性及规律，揭示面板损伤开裂模式及破损机制，据此提出高韧复合面板新概念。采用室内加载试验，揭示高韧混凝土-普通钢筋混凝土工作机理及破坏机制，提出高韧复合面板计算模型，优化高韧复合面板的范围及尺寸。研究永久水平缝对面板地震应力及其破损程度的影响，探明面板与垫层间加筋的抗错台作用机制。在此基础上，提出局部采用高韧复合面板、高应力区设置永久水平缝和面板后垫层内加筋等多种措施的集成抗震对策，研究其对减缓面板高应力和损伤程度的效果，阐明三者协调工作及相互作用机理。

我国西南地区正规划建设多个300m级超高面板堆石坝，而该地区地震活动频繁且烈度较高，一旦遭遇强震，将可能产生堆石体震陷、滑坡，进而导致面板破损、防渗功能丧失等严重灾害。本项目采用三维有限元数值分析方法，对面板地震响应特性开展了系统研究，确定了面板高应力区范围，指明了面板抗震薄弱部位。引入混凝土多轴强度准则，改进了面板抗震安全评价标准及评价方法。采用基于堆石体和接触面的广义塑性模型的弹塑性分析方法，从面板受力状态角度对面板动力破损形态、破损机理开展了系统研究。在此基础上，引入混凝土共轴旋转裂缝模型，对面板动力开裂、渐进破坏过程进行了模拟，阐明了面板动力开裂破坏特性。在上述研究成果基础上，分别从结构设计的改进和材料性能的提高两个方面，提出了能够大幅度提高面板抗震性能的工程对策，并利用数值分析方法定量评价了抗震措施的有效性。.本项目取得了多项创新性成果，发展了筑坝堆石料广义塑性本构模型，建立了强震作用下超高面板坝弹塑性损伤渐进破坏分析方法。揭示了高面板坝面板高应力区分布规律，确定了面板抗震关键区域，首次提出了可大幅降低面板地震应力的水平抗震缝及其设置范围。发展了基于混凝土多轴强度准则的面板安全评价方法，从面板多轴受力特性角度阐明了面板动力破损机理，指明了单轴强度准则在判别面板安全性时的局限性。提出了一种具有动力抗裂性能的新型面板结构形式，发展了既可以模拟材料应变硬化特性、又可以模拟材料应变软化特性的面板非线性分析方法，利用该方法定量评价了普通面板和新型面板的抗震性能。以上成果为我国300m级高面板堆石坝抗震设计提供了理论支撑。