泥沙异重流与环境物质交换经验式对比

Numerical comparative studies on the performances of empirical relations of mass exchanges for turbidity current

采用异重流层平均水沙耦合数学模型,模拟开闸式和恒定入流式泥沙异重流水槽实验,对比分析异重流与环境之间物质交换经验式的适应性和不确定性。考虑4个水卷吸经验式:ew59、ew86、ew87和ew01,5个泥沙侵蚀经验式:E_s77、E_s86、E_s87、E_s93和E_s04。数值研究表明:水卷吸对于水槽异重流影响较小,应用综合考虑底床摩擦和剪切不稳定的ew经验式时模拟结果较好;开闸式异重流对床面侵蚀能力有限。对于恒定入流式异重流,应用E_s87和E_s93侵蚀经验式计算所得淤积厚度与实测值吻合较好,可能是率定时综合考虑了异重流实验数据。

In this paper,a layer-averaged fully coupled model is applied for simulating both laboratory lock-release and constant-flux turbidity currents with the aim of analyzing the applicability and uncertainties of empirical relations for the water and sediment entrainment process.For this purpose,the performance of four empirical formulae（i.e.,ew59,ew86,ew87 and ew01） for the water entrainment and five（i.e.,E_s77,E_s86,E_s87,E_s93 and E_s04） for the sediment erosion are compared.The following understandings are drawn from numerical case studies.The water entrainment has mild effect on small-scale turbidity currents,though simulation results with the ew01 relation are slightly better than those by others.It might be due to the fact that the ew01 relation has taken into account of the effects of both bottom and upper interface resistances.Lock-exchange turbidity currents are mainly depositional and thus less sensitive to the choice of erosion relations.For constant-flux turbidity currents,the E_s87 and E_s93 relations appear to perform best.This must be attributed to the fact only these two erosion relations have been calibrated using experimental turbidity current data.This study should help further studies for developing and calibrating empirical relations of mass exchange for turbidity currents.