基于序贯决策的高堆石坝施工度汛风险时空耦合控制机理研究

In the construction process of high rock-fill dams, large variable of flood water level and flow、long construction period and huge filling volume due to dam site area between high mountains and deep valleys. Therefore, flood risk control for high rock-fill dams is the key to ensure dam safety and economic construction in flood period .This research aims at the key scientific problems of flood risk space-time coupling and control process of high rock-fill dam. Firstly, risk analysis model of flood handling based on observed flood series is built. The coupling effect among water retaining risk、filling schedule and section height is distilled in the view of space-time, then probability distribution function of filling schedule and height is derived as well as mathematical expressions of dynamic evolution of risk. Temporal variation characteristic and flood risk distribution of high rock-fill dams is revealed. Secondly, sequential decision model for flood handling based on Markov process is put forward. Next, Risk control parameter system is obtained by united modeling language based on oriented-object. Finally, risk adaptive control model is set up to reveal risk space-time coupling control mechanism for flood handling during high rock-fill dam construction. Moreover, simulation is carried out for analyzing risk control process. The research results can provide a theoretical basis for real-time risk control and method for assistant dynamic decision-making in the high rock-fill construction process.

高堆石坝多集中在高山峡谷地区，洪枯水位和流量变化幅度大，施工填筑量大、填筑周期长。施工度汛风险控制是确保大坝汛期安全经济施工的关键。本项目拟针对高堆石坝施工度汛风险时空耦合及其过程控制这一关键科学问题，以度汛风险为研究对象，建立基于实测洪水序列的风险率计算模型；从时空角度提炼度汛过程中的挡水风险-填筑进度-断面高程间的耦合关系，推导大坝填筑时空的概率分布及风险动态演进数学表达，揭示高堆石坝施工度汛风险的时序变化特征和分布规律；针对度汛过程的随机动态特性，提炼其马尔科夫性，构建基于马尔科夫过程的度汛序贯决策模型；采用面向对象的建模语言图形化描述风险控制参数体系，构建序贯决策驱动下施工度汛风险自适应控制模型，揭示高堆石坝度汛风险时空耦合控制机理。在此基础上对高堆石坝施工度汛风险控制过程进行仿真分析。研究成果可为高堆石坝施工度汛风险实时控制提供理论依据，为高堆石坝施工度汛动态决策提供方法支撑。

随着我国水电工程建设重心逐步向西南、西北地区转移，一系列 200 m 级以上高堆石坝工程相继开工建设。这些工程多集中在高山峡谷区域，洪枯水位和流量变化幅度大、填筑周期长。施工导流贯穿工程施工的全过程，挡水风险与施工进度相互制约，具有明显的时空动态特性。尤其是中后期导流度汛阶段，当坝体填筑高程超过围堰堰顶高程后，度汛方案的科学决策和施工进度的合理安排，是确保大坝在汛期安全经济施工的关键。本项目针对高堆石坝施工度汛风险时空耦合及其过程控制这一关键科学问题，以度汛风险为研究对象，首先，对历史洪水资料进行整理，系统研究施工洪水特性，分析洪水洪量与洪峰之间的相关性。优选Copula函数构造洪水洪峰-洪量联合分布，考虑施工填筑区强度及有效施工天数建立汛期大坝逐月填筑高程仿真模型，分析坝址日降雨量及堆石坝因雨停工标准对有效施工天数的影响。基于Monte-Carlo法，考虑水文、水力、有效施工天数和坝体填筑强度等随机因素，建立了基于实测洪水序列的峰量联合度汛风险率计算方法。其次，考虑决策者风险偏好，在得到逐月度汛风险率的基础上，以度汛决策阶段可接受风险率作为期望轨迹对实时风险率进行跟踪。以实体轨迹逼近期望轨迹为目标，基于自适应控制理论构建堆石坝施工度汛挡水风险动态控制模型，以动态调整高堆石坝挡水高程，控制度汛挡水风险至可接受范围内。再次，以整个度汛施工期成本最小化为目标，考虑洪水来流、填筑进度和决策成本等关键因素，建立基于马尔科夫过程的高堆石坝施工度汛决策模型，分析逐月大坝挡水风险状态下的度汛策略、成本函数和风险状态转移概率。在检验其马尔科夫特性基础上，采用决策迭代算法求解每一决策时刻状态下的最优施工度汛方案及度汛过程的决策路径。最后，构建了高堆石坝施工度汛风险仿真系统。项目研究成果可为实时预测施工度汛风险，调整施工进度、减小防汛成本提供技术手段，同时也可为高堆石坝度汛方案优化和施工进度精细化控制提供参考。