【作者】 张甫杰；

【导师】 陈健云；

【作者基本信息】 大连理工大学 ， 水工结构工程， 2008， 硕士

【摘要】 随着我国水利水电事业的发展和筑坝技术的迅速提高,在水力资源丰富的西部地区正在设计修建高碾压混凝土重力坝,而这些地区正是高烈度地震频发地区,有的设防地震烈度甚至达到了Ⅸ度。在这种高烈度地震作用下,碾压混凝土重力坝的抗震安全直接关系到下游广大地区工农业生产和人民生命财产的安全,具有特别重大的现实意义。因此,本文采用有限元动力分析方法,对龙开口碾压混凝土重力坝的动力特性及其抗震安全性进行了研究和探讨,最后确定了大坝的抗震薄弱部位,并提出合理的工程抗震措施,为大坝的设计提供保证。主要做了以下几方面的工作:(1)已有研究表明,对混凝土坝抗震采用线弹性分析得到的最大拉应力远大于混凝土的抗拉强度,在强震作用下,坝体将不可避免地产生开裂。主要研究了龙开口非溢流坝段采用混凝土损伤塑性模型在自重、静水压力以及地震荷载作用下的动力特性、拉伸损伤分布、塑性应变分布、等效塑性应变分布、破坏路径、动力放大倍数以及耗散能。并在此基础上探讨了典型地震波、阻尼比及设计水平加速度对坝体安全可靠度的敏感性影响。(2)由于重力坝在坝踵处拉应力很大,常超出了混凝土的抗拉强度极限,因而在坝踵位置很容易产生裂缝,进而影响坝体的稳定。根据小湾拱坝计算所得的“坝基裂隙的存在对坝踵应力集中起到松弛释放的作用”这一结论,以改善坝踵处应力分布状态为目的,设想在坝体上游基岩上设置一条垂直诱导缝,在此基础上研究地震作用下诱导缝的设置对于坝体应力的影响以及通过优化分析求出其最优解。(3)在详细分析坝体开裂现象的基础上,研究了重力坝的动态开裂机理、钢筋混凝土的断裂能以及预应力锚索的数值模拟。针对此现象提出了工程抗震措施,主要包括坝体配筋和预应力锚固两种措施,并给出加固前后的拉应力损伤因子对比分析,以验证加固措施的有效性。更多还原

【Abstract】 Now with the rapid development of water conservation and RCC dam technology, some high RCC gravity dams will be constructed in western region with plentiful water resources and frequent earthquake. The adopted design level of earthquake ground motion reached to nine degrees in these regions. It is very significant that aseismic safety for industrial and agricultural production and the safety of the people’s life and property in the large region of downstream under high intensity seismic action. Therefore, in order to study deeply the dynamical characteristics and aseismic safety of Long Kai Kou RCC gravity dam in high earthquake intensity, dynamical analysis of the finite element method is used. Finally, weak zones of the dam are determined and the reasonable aseismic measures are also proposed. Thus it ensures the reliable design of dam. The main works of this paper are as follows:(1) The known studies indicate that peak tensile stress occurred at the upper portion of concrete gravity dam is much higher than the dynamic tensile strength of concrete during strong earthquake which resulted in the inevitably happening of cracking.The paper mainly studies the dynamic characteristics, damage distribution, plastic distribution, equivalent plastic distribution, damage course, acceleration amplification and dissipated energy of LKK non-flow dam under dead weight、hydrostatic pressure and seismic load. On this base, the influence of typical seismic waves、structural damping ratio and design horizontal acceleration on the safety reliability of dam were studied.(2) Due to the tensile stresses at dam heel are too high, the value often exceeds concrete strength of extension, so cracks come into being in dam heel easily, which then effects stability of dam body. According to the conclusion of " the dam foundation fracture played main role in the relaxation of stress concentrate in the dam heel" ,which calculated by Xiao Wan arch dam. In order to improve the stress distribution in the dam heel zone, the author assumes an induced joint on the bed rock of dam body upstream. On this basis induced joint arrangement under earthquake action and the effect of dam stress have been discussed. Morever, the optimal solutions are achieved through optimization design.(3) Based on the detailed analysis of dam cracking phenomena, the cracking mechanism, reinforced concrete fracture energy and prestressed anchor cable numerical simulation are studied. Pointing to this condition aseismic measures are put forward. It mainly includes reinforcement and prestressed anchor, also provides the result of tension damage factor comparative analysis, and demonstates the efficiency of the reinforcement measures.更多还原