高拱坝气幕隔震及其非线性效应的数值仿真

Numerical Simulation for Air Cushion Isolation of High Arch Dams Considering the Nonlinearity Effect

为了研究气幕非线性对高拱坝气幕隔震效果的影响,基于高拱坝气幕隔震控制的气-液-固3相耦合数值模型,在该模型中引入了气幕的材料非线性,完成了锦屏一级高拱坝在汶川地震波作用下的气幕隔震效果研究,并与不考虑气幕非线性的计算结果进行了对比。结果表明:气幕可以显著降低拱坝上游坝面的动水压力。气幕厚度为1 m时,正常蓄水位及死水位工况,上游坝面最大动水压力分别降低70.2%和75.3%。气幕使拉应力的量值普遍降低,应力分布得到改善,拱坝的整体抗震性能得到显著提高。气幕非线性所导致的动水压力误差小于10%,因此,当动水压力在总水压力中所占比例较小时,可忽略气幕单元的材料非线性。

In order to study the influence of nonlinearity to air cushion isolation effects of high arch dams, the gas-liquid-solid tri-phase coupling numerical model of the air cushion isolation control of high arch dams was presented, in which the material nonlinearity of air cushion was considered. The isolation effect simulation of Jinping high arch dam under Wenchuan seismic wave was carried out,and the results were compared to the ones neglecting the air cushion nonlinearity. It was showed that air cushion reduces the hydrodynamic pres- sure significantly. In normal and dead water level,the maximum of hydrodynamic pressure is reduced 70.2% and 75.3% , respectively with l m air cushion. Air cushion also causes a general reduction of tension stress and an improvement of stress distribution. Thereby, the anti-seismic capacity of the arch dam is improved significantly. Compared with the results neglecting the air cushion nonlinearity,the error of hydrodynamic pressure is less than 10%. Therefore ,when the proportion of hydrodynamic pressure in total pressure is smaller, the material nonlinearity of air cushion can be ignored in air cushion isolation simulation of high arch dams.