强震动随机性对重力坝动水压力影响研究

Influence of Randomness of Strong Ground Motion on Hydrodynamic Pressure of Gravity Dam

针对现行水工抗震规范推荐的动水作用计算方法未考虑地震动随机性的问题,研究了强震动随机性对动水压力的影响。首先以Westergaard级数解为基础,探讨声固耦合法模拟动水压力的可行性;然后以选取的25条天然波和生成的25条人工波为基础,研究强震动随机性对重力坝动水压力分布规律和最大值的影响。结果显示,Westergaard级数解仅适用低频激振力,声固耦合法对不同频率的激振力均适用;在动水压力分布规律方面,刚性地基情况下与Westergaard附加质量法规律一致,弹性地基情况下与规范推荐的动水压力系数规律相似;在强震动随机性影响方面,人工波随机性带来的动水压力最大值对均值的偏离程度为16.1%~22.2%,天然波随机性带来动水压力最大值对均值的偏离程度为39.4%~49.8%,天然波随机性对动水压力的影响是人工波的2.0~2.5倍。

The influence of the ground motion randomness on the hydrodynamic pressure of gravity dams,which cannot be considered by methods from the code,is investigated in this paper.Firstly,based on the series solution of Westergaard,the feasibility of the acoustic-structure coupling method for simulation of the hydrodynamic pressure is investigated.Then,based on 25 selected natural waves and 25 generated artificial waves,the influence of the randomness of strong ground motions on the hydrodynamic pressure is investigated.The results show that the series solution of Westergaard is only suitable for low excitation frequencies,and the acoustic-structure coupling method is universal for different excitation frequencies.The distribution of the hydrodynamic pressure is consistent with the Westergaard method in rigid foundation conditions,and is similar to the hydrodynamic pressure coefficient given by the code in flexible foundation conditions.The deviation of the maximum hydrodynamic pressure from the mean value by artificial wave randomness is from 16.1%to 22.2%,while the ones by natural wave randomness is from 39.4%to 49.8%.The influence of the randomness from the natural waves is about 2.0-2.5 times that from the artificial waves.