考虑水沙相互作用的河堤溃决二维数值模型

该文建立了洪水漫堤导致河堤溃决的平面二维水沙运动数值模型,以模拟溃口扩展和堤身冲刷的过程。该模型基于有限体积法、采用显式格式求解平面二维水流运动和非平衡全沙泥沙输移方程,并考虑了边坡崩塌、底床急剧变形以及高浓度泥沙输移对水流运动的影响。溃口处的混合流场采用HLL approxim ate Riemann solver处理,非黏性土溃口边坡的崩塌采用不同干、湿静止角处理。通过对英国HR Wallingford实验室一组实验的计算,结果表明该模型能较好地模拟非黏性土堤坝溃决过程中的溃口展宽、坝体冲刷、流场分布以及溃口流量过程线。对模型参数的敏感性分析显示了水沙耦合溃决模型的非线性特征。

Two-dimensional levee breaching model considering flow and sediment interaction

A two dimensionnal dam/levee breaching model was developed to simulate overtopping flows, breach development, and the related sediment transport processes. The depth-averaged 2-D flow and non-equilibrium total-load sediment transport equations were solved using an explicit finite volume method on a rectangular grid. The model considered interactions among transient flow, strong sediment transport and rapid bed distortion by including bed change and variable flow density in the continuity and momentum equations of flow. The HLL approximate Riemann solver was used to handle the mixed-regime flows near the breach, and different repose angles for the sediments below and above the water surface were adopted to handle the non-cohesive embankment slope avalanching. The model was checked against the laboratory experiment carried out by HR Wallingford, UK, and the results show that the developed model predicts well the breach dimension, flow hydrograph, and flow characteristics. The sensitivity analysis shows the nonlinear features of the model.