细颗粒黏性原状土的冲刷特性试验研究

摘要

Based on physical model test, according to the measured erosion rate and bed shear stress, erosion characteristics of cohesive undisturbed fine soil were analyzed,considering the influence of water pressure and criti-cal incipient condition on the parameters of the source term for scour rate formula.The results show that in different water pressure and incipient condition, the relation between erosion rate and relative residual shear stress of silt and fine sand is changeless.The energy index of silt is at around 0.5, and the energy index of fine sand is at around 1. The scouring coefficient of a general continuous incipient condition is slightly bigger than that with a small amount of incipient motion as a starting state.In addition, the scope of silt scouring coefficient is (0.8~9.8)x10 -2 kg. m2.s-1,and the scope of the fine sand erosion coefficient is (0.2~5.5)x10 -2 kg.m2.s-1, The impact resistance of sand is slightly stronger than that of silt.%基于物理模型试验,根据实测的冲刷率和床面切应力来分析细颗粒黏性原状土的冲刷特性,考虑水压力的大小和临界起动状态的不同对冲刷率源项公式参数的影响.结果表明:在不同的水压力下,粉沙和细沙的冲刷率都与相对剩余切应力成相同的指数关系,中值粒径较小的粉沙的能量指数取0.5,细沙的能量指数取1.以普遍连续起动为起动状态的冲刷系数较以少量起动状态作为起动状态要略大,能量指数要略大.此外,粉沙的冲刷系数为(0.8~9.8)×10-2 kg·m2·s-1,细沙的冲刷系数为(0.2~5.5)×10-2 kg·m2·s-1,细沙的抗冲性能要略强于粉沙.