考虑流固耦合的重力坝地震开裂过程模拟

Seismic cracking simulation of gravity dams considering fluid-structure interaction

大坝抗震安全评价是一项重要工作。首先建立了考虑坝-基-库水相互作用的重力坝整体分析模型,采用声学单元模拟库水域,并通过若干算例验证了该模拟方法的可行性。然后采用扩展有限元法模拟坝体裂缝的开裂扩展过程,建立考虑裂缝面张开-闭合的接触模型。以金安桥碾压混凝土重力坝为例,建立该重力坝-地基-库水动力相互作用模型,探讨附加质量法及是否考虑库水可压缩性的流固耦合模型对重力坝地震开裂过程的影响,分析该重力坝在有缝状态下的超载潜力及初始裂缝位置对裂缝开裂扩展的影响。结果表明:附加质量法和不考虑库水可压缩性均夸大了地震作用力,裂缝开裂扩展更大,开口更加明显;随着地震峰值加速度的增大,该重力坝裂纹扩展路径向下偏转的起始位置向坝体内部延伸,在1.3倍设计地震加速度的地震荷载作用下,大坝将产生较长裂缝;折坡点处的初始裂缝在地震荷载作用下裂纹扩展更明显。研究结果可用于大坝遭遇强震时的开裂预测,为实际工程提供参考。

Dam seismic safety is a key technical problem related to national water resources safety,and even social and public safety.Seismic safety evaluation and dynamic interaction analysis of dams are important in practical engineering.In this research,an overall analysis model of gravity dams considering dam-foundation-reservoir interaction was established,the reservoir was simulated by acoustic elements,and the feasibility of this simulation method was verified by several examples.Then,the crack propagation process of the dam was simulated by the extended finite element method,and the contact model considering the opening and closing of the crack surface was established.Taking Jin'anqiao RCC gravity dam as an example,the gravity dam-foundation-reservoir-dynamic interaction model was established.The effects of the additional mass method,the fluid-structure coupling model without considering the compressibility of the reservoir and the compressibility of the reservoir water on the seismic cracking process of the gravity dam were discussed.The overload potential of the gravity dam with cracks and the influence of the initial crack position on the crack propagation were analyzed.The results show that the additional mass method and fluid-structure coupling model without considering the compressibility of reservoir water exaggerate the earthquake action,and a longer crack propagation and larger crack can be observed.With the increasing of the seismic peak acceleration,the initial position of the downward deflection of the crack propagation path of the gravity dam continues to extend to the interior of the dam,and the dam will produce long cracks under the seismic load with the seismic load of 1.3 times of the design seismic acceleration.The initial crack at the slope break point propagates more obviously under seismic load.