黄河口粉质土沉积物侵蚀性动态变化试验研究

Laboratory study about the influence of dynamic loading on the erosion of silty sediment in the Huanghe Estuary in China

通过一系列室内试验,研究了黄河口粉质类沉积物在循环动荷载作用后侵蚀性的变化。在试验中,采用真空预压固结装置制备重塑土样,采用液压伺服土动三轴试验机实现了不同幅值及不同振次的动荷载作用条件,并通过动三轴静态试验及贯入强度测试,测定了动荷载作用后土样强度的变化。通过水槽冲刷试验测试了不同条件的动荷载作用后,土样抗冲刷能力的变化,并进行了临界剪切应力的计算。试验结果表明:对于黄河口粉质类沉积物,动荷载作用后其强度及抗侵蚀性均降低;沉积物强度指标(不排水剪切强度、残余强度、贯入阻力)、侵蚀性指标(起动流速、临界剪切应力、冲刷率)与动荷载幅值、动荷载振次均呈现出较好的线性相关性。

In order to study the silty sediment erosion variety under the dynamic circulative loading, a series of indoor tests were processed. The remoulded soil samples were prepared by the vacuum preloading. The dynamic loading, in different magnitudes and acting times, was exerted on the samples using the dynamic triaxial device. When the dynamic loading ended, the undrained shear strength and residual strength were continuously mensurated in the static test. The parallel samples were directly taken out from the dynamic triaxial device after dynamic loading for the penetration strength tested by the electronic digital display micropenetrometer. Then the scour experiments were carried out to mensurate the threshold velocity and the erosion rate. What is more, critical shear stress was calculated by the empirical equation. The results show that both antierosion and strength of the silty soil are decreased after the dynamic loading action, and it is also found that the silty erosibility parameters of the threshold velocity and the erosion rate have a significant linear correlation with the dynamic loading conditions including the loading magnitude and acting times, and it is the same with the silty sediment strength parameters of the undrained shear strength, the residual strength and the penetration strength.