河道截流系统风险率计算模型及计算方法研究

Research on Risk Probability Model and Calculation Method for River Closure System

为了对水利水电工程河道截流方案进行科学决策,简要回顾了截流风险的研究进程,并基于工程实际对截流系统进行了风险识别,分析了截流中可能遇到的风险事件类别及其影响因素。考虑水文、水力和施工的不确定性,建立了基于龙口轴线断面平均流速、龙口轴线水深和平均抛投强度的截流系统综合风险率估计数学模型,使截流风险率计算更加完善。对比了目前存在的风险计算方法的优劣,提出用基于完整水力学计算的Monte-Carlo法计算风险率。最后,对于计算中多风险变量的相关性、动态和静态风险区分、抽样次数、抽样误差等问题进行了讨论,并结合具体算例进行了分析。计算结果表明,截流系统综合风险率随截流设计流量的不同有较大变化,并与反应施工组织水平的抛投强度密切相关。

To make scientific decision on river closure for water conservancy and hydropower projects,this paper firstly makes a brief review on the research history of river closure risk.Based on the actual engineering,the random factors of river closure system are identified,and the resulting factors of possible risk events are analyzed.Taking the hydrological,hydraulic and construction uncertainties into consideration,a new mathematical model is proposed and the calculation of risk probability for river closure system is improved.The model uses average velocity,water depth and average dumping intensity at the closure gap axis as risk variables to assess the integrated risk of the river closure system.Furthermore,by comparing the defects and merits of different calculation methods,the Monte-Carlo method of calculating the risk probability based on complete hydraulic calculation is put forward.At last,problems including the correlation of risk variables,dynamic and static risk differentiation,sampling frequency,and sampling error are discussed and a specific numerical example is presented.The calculation results show that the integrated risk of the river closure system varies greatly with the change of designed discharge and is closely correlated with dumping intensity which indicates the organizing ability of the construction.