钱塘江河口海塘风险分析和安全评估关键技术

Key technology for risk analysis and safety evaluation of Qiantang River seawall

在总结以往风险分析的基础上,分析了钱塘江河口海塘的风险因子,结合钱塘江河口河床易冲易淤的特点,建立了海塘失效概率树模型,得出了海塘风险分析的基本框架.海塘失效概率树为串联概率树,而条件概率P(B/A)解求是串联概率树要解决的关键问题,为此提出了假定条件概率近似符合正态分布,然后做积分变换推求条件概率的思路;在进行钱塘江河口海塘风险分析和安全评估时,要注意引入塘前滩地高程作为分析海塘整体稳定安全性的随机变量;采用信息熵理论分析高水位变异点,以及放水减淤、船抛块石等降低海塘失效风险措施研究等关键技术问题.

Based on relevant previous studies, several risk factors affecting the Qiantang River seawall were brought forward. The corresponding fault tree model and the schematic ideals for systematic risk analysis on the reliability of the seawall were also provided for considering that the riverbed＇s characteristics changes greatly and rapidly. The seawall fault tree is the system in series, and the key to the fault tree is the solution to conditional probability P（B/A）. So the idea of solution to conditional probability by integral transform was presented on condition that its probability density function obeyed normal distribution. The flat level in front of the seawall was regarded as a random variable. Analysis of the high water level variation by the theory of information entropy, and practical technique such as using runoff for erosion, dumped riprap to reinforce the seawall were emphasized as the key technology of risk analysis and safety evaluation of seawall.