应急防洪条件下重力坝抗滑稳定可靠度分析

混凝土重力坝应在流域梯级水库群应急防洪调控中发挥超蓄洪水作用,而运行期大坝安全可靠性定量评估是梯级水库群应急防洪调度的关键边界条件,因此需要研究基于实测资料的重力坝抗滑稳定可靠度计算方法。首先基于渗压监测成果和水文气象预报资料,提出了坝基扬压力变异系数的估计方法,进而结合一阶二次矩方法计算抗滑稳定可靠度;然后,以向家坝工程为例,给出大坝在运行期和超蓄洪水条件下的安全风险定量评估结果,并与传统的安全系数法进行了对比,进而讨论了计算假定、可靠度计算方法、随机参数敏感性对计算结果的影响。研究成果可作为基于贝叶斯网络的应急防洪调度方案计算方法的组成部分,为梯级水库群应急调控方案编制提供科学决策依据。

Reliability analysis on anti-sliding stability of gravity dam under emergency flood control condition

Concrete gravity dam must play a role of over-storage of flood for the emergency flood control operation of cascade reservoir group of a river basin, however, the quantitative assessment on the safety and reliability of a dam during operation is just the key boundary condition for the emergency flood control operation of cascade reservoir group, and then the measured databased calculation method for the reliability of the anti-sliding stability of concrete gravity dam is necessary to be studied. At first, the assessment method of the uplift variation coefficient of dam foundation is put forward on the basis of the seepage monitoring results and the hydro-meteorological forecast data, and then the reliability of the anti-sliding stability is calculated in accordance with the first-order second-moment method, afterwards, the result of the quantitative assessment on the safety risk of dam during operation period and under the condition of over-storage of flood is given out by taking Xiangjiaba Project as the actual case, which is compared with that from the conventional safety factor method, furthermore, the influences from the relevant calculation assumptions, reliability calculation methods and random parameter sensitivities on the calculation are discussed as well. The study results can be taken as a component part of the calculation method for the Beyesian Network-based emergency flood control operation scheme and then provide a scientific decision-making basis for making the emergency operation and control scheme for cascade reservoir group.