不同盐度固结黏性泥沙的冲刷试验研究

Experimental Study on Scouring of Consolidated Cohesive Sediment with Different Salinity

在近海岸及河流入海口,由于潮汐等因素的影响,泥沙的盐度条件十分复杂。为更好地研究近海岸及河口复杂盐度条件下海岸及河岸的侵蚀速率,将两种不同级配的泥沙制成含盐度分别为0‰、5‰、10‰、20‰、30‰、40‰的固结泥块,测定了其干密度、含水率等物理性质指标,并开展固结泥块冲刷特性的水槽试验研究,分析了固结泥块的冲刷系数与起动切应力、起动切应力与干密度、干密度与盐度之间的关系,得到了冲刷系数随盐度变化的表达式。分析结果表明:在0‰~40‰的盐度范围内,盐度(x)越大,冲刷系数(k d)越小,泥块越不易被冲刷,其拟合关系为k_(d)=-0.0141x^(1.883)-0.2376x^(1.115)+78.9017。研究结果可以为海岸和河流边坡的防护、海岸和河岸的侵蚀速率计算提供参考。

Due to the influence of tides and other factors,the salinity conditions of sediment near the coast and at the mouth of rivers are very complex.In order to better study the erosion rate of coastal and river banks under complex salinity conditions near the coast and estuaries,two types of sediment with different gradations were made into consolidated mud blocks with salinity levels of 0‰,5‰,10‰,20‰,30‰,and 40‰,respectively.In this study,its dry density,moisture content and other physical properties were measured,and a flume test was carried out on the scouring characteristics of consolidated mud.The relationship between scour coefficient and priming shear stress,priming shear stress and dry density,dry density and salinity of consolidated mud is analyzed,and the expression of scour coefficient changing with salinity is obtained.The results are as follows.In the salinity range of 0‰to 40‰,the higher the salinity(x)is,the smaller the scour coefficient(k d)is,and the mud blocks are more difficult to scour.The fitting relationship is k_(d)=-0.0141x^(1.883)-0.2376x^(1.115)+78.9017.The research results can provide reference for the protection of coastal and river slopes,as well as the calculation of erosion rates of coastal and river banks.