尾矿库漫顶溃坝机理与溃坝过程数值模拟

Breach mechanism of tailings dam due to overtopping failure and numerical simulation of breach process

针对尾矿库漫顶溃坝问题,采用尾矿库漫顶溃坝离心模型试验,研究挟砂漫顶水流作用下的溃口尺寸和溃口流量的演化规律,并将尾矿库溃坝过程分为下游坡冲蚀、溯源冲蚀、沿程冲蚀3个阶段;在此基础上建立沿深度取积分平均值的二维溃坝数学模型,该模型可考虑坝坡上重力分量对冲蚀率的影响以及溃坝过程中溃口边坡的失稳坍塌。采用全耦合方法将水动力方程和非平衡坝料冲蚀方程转换为含源项的浅水方程形式,并基于矩形网格下的有限体积法进行离散处理和数值求解。采用双侧扩宽水槽中动床试验和尾矿库漫顶溃坝离心模型试验对模型的合理性进行验证。研究结果表明:采用本文所提模型得到的溃口最终形态、溃口流量变化过程和溃口断面发展过程与实际情况基本吻合,验证了模型的合理性。

Aiming at the problem of overtopping of tailings dams,the centrifugal model tests of overtoppinginduced dam breach of tailings dams were conducted.The evolution rules of breach size and flow discharge under the action of the sand-carrying overtopping flow were revealed,and the breach process was divided into three stages:downstream slop erosion,retrogressive scour and streamwise erosion.On this basis,a two-dimensional mathematical dam breach model based on the integral mean with depth was developed,in which the influence of the gravity component of the dam slope on the erosion rate and the instability of the breach side slopes during dam breaching process were considered.The full coupling method was adopted to convert the hydrodynamic equation and the non-equilibrium dam material erosion equation into the shallow water equation form with the source term,and the discrete processing and numerical solution were conducted based on the finite volume method with the rectangular grids.Subsequently,double-sided widened flume test for breach flow over mobile bed and centrifugal model test for tailings dam breach due to overtopping failure were chosen as representatives to verify the rationality the numerical model.The results show that the final breach morphology,the breach flow hydrographs,and the development process of the breach cross-sections obtained by the proposed model are basically consistent with the actual situations,which testifies the rationality of the proposed model.