钱塘江下沙海塘越顶安全性分析

钱塘江河口大规模治江围涂,导致仓前站年最高水位持续抬升,削弱了海塘安全性.采用信息熵理论,通过构造水位比较序列的差异信息相对测度,分析了钱塘江水位系列发生变异的年份,结果表明1974年、1997年为仓前站水位变异点,在此基础上分析了不同时段各频率水位.采用JC法建立了海塘越顶安全性分析模型,以下沙海塘为例进行越顶安全性分析,得到通常条件下下沙海塘发生越顶的概率为1.80×10-3；敏感性分析表明,影响海塘越顶安全性的最显著因素为外江水位特征,在遇超强台风等非常条件下,当外江水位偏差系数增加到0.1时,下沙海塘越顶概率为0.0254.

Analysis of overtopping probability of Xiasha seawall on Qiantang river

Large-scale reclamation in estuarine reach of Qiantang river causes a continuously increasing of annual high water level in Cangqian station, which weakened the safety of the constructed seawalls. The analysis of differential information comparative measure, which was based on the information entropy theory and the conformation of differential comparative series of high water level, showed that the water level variation of Cangqian station happened in the years of 1974 and 1997, and the frequency curves of the water level for different periods of time were acquired. A mathematical model for calculating the probability of seawall overtopping was constructed by JC method. Taking Xiasha seawall as a case, the probability of seawall overtopping is evaluated to be 1-80×10-3 generally. Further sensitive analysis demonstrated that the water level characteristics is the major reason for occurrence of overtopping, and the risk of overtopping is 0.0254 when the variance coefficient of water level increases up to 0-1 or under the unusual conditions such as the super strong typhoon.