考虑材料冲蚀性沿深度变化的堰塞体漫顶溃决模拟

Numerical modeling of barrier dam overtopping-induced breach process considering barrier soil erodibility variations along depth

合理预测堰塞体的溃决过程对于致灾后果评价和防灾减灾工作的开展具有至关重要的意义,但由于堰塞体结构和材料的复杂性,给预测工作带来了挑战。基于堰塞体的地质勘察资料和溃决机理,建立了一个可考虑材料冲蚀特性随深度变化的堰塞体漫顶溃决过程数学模型。模型主要包括水动力模块、材料冲蚀模块和溃口发展模块,并采用按时间步长迭代的数值计算方法模拟堰塞体溃决时的水土耦合过程。选择拥有实测资料的白格"11·03"堰塞体溃决案例对模型进行验证,模拟结果验证了模型的合理性。参数敏感性分析结果表明,堰塞体材料冲蚀系数对溃口流量过程具有重要影响,堰塞体材料临界剪应力对溃决过程影响较小;另外,开挖泄流槽可大幅降低库容较大堰塞湖溃决时的溃口峰值流量,是一种行之有效的减灾手段。

Reasonable prediction of barrier dam breaching process is of significant importance for disaster consequences evaluation and disaster prevention and reduction work implementation.However,due to the complexity of barrier dam’s structure and materials,the prediction is full of challenges.Based on the geological survey data and breach mechanism of barrier dam,a numerical model for the overtopping-induced breaching process of barrier dam is developed,which considering the variations of barrier deposits erosion characteristics along the depth.The model mainly includes hydrodynamic module,soil erosion module and breach development module,and the numerical calculation method based on time step iteration is adopted to simulate the soil and water coupling process during dam breaching.The"11.03"Baige barrier breach was selected to verify the model with measured data,and the simulation results verified the rationality of the model.The parameter sensitivity analysis results show that the barrier soil erosion coefficient has important influence on the breaching process,the critical shear stress of barrier soil has relatively small influence on the breaching process.Further,the excavation of spillway can greatly reduce the peak breach flow for large barrier lake,which is an effective means of disaster reduction.