船行波对内河饱和软黏土刚度和强度弱化影响试验研究

Experiment research of the stiffness and strength of saturated clay in inland waterway under ship wave

近年来随着内河航运业的发展和船舶大型化的趋势,船行波对内河航道岸坡的稳定性影响不容忽视。船行波是一种动荷载,长期作用于内河表层饱和软黏土,对其刚度和强度影响严重。通过动三轴试验模拟了船行波对内河饱和软粘土的刚度和强度的影响,并对动三轴试验后的土样进行不排水剪切试验,研究了船行波荷载长期作用后内河表层软粘土的强度弱化。通过研究建立了考虑循环荷载比的软化指数经验公式;建立了考虑循环荷载比的土体残余应变计算经验公式,并在此基础上建立了土体强度折减与残余应变的关系;最后依据莫尔库伦准则给出土体粘聚力和内摩擦角的强度折减系数与循环应力比关系经验公式。

Because of the development of inland water transportation and trend of larger inland navigation ves-sels, the ship wave affects the bank slope stability of inland waterway. As we know, the ship wave, a special type ofdynamic load, influences the saturated clay on the surface of the bank slope of inland waterway and causes the deg-radation of both the stiffness and strength of the saturated clay. Dynamic tri-axial tests were conducted to simulatethe effects of ship wave to the saturated clay, and then a series of undrained shear tests were performed in order todetermine the degradation of the saturated clay after a long term of ship wave loading. Depending on the experimentresults, the empirical model, considering the effect of cyclic stress ratio, for calculating degradation index was estab-lished. Also, the empirical model for predicting the development of residual strain was proposed and the relation-ship between model parameters and cyclic ratio was discussed. Finally, based on the predictable model for calculat-ing residual strain, an empirical model for calculating the degradation of strength was proposed, moreover, the reduc-tion ratio of cohesion and internal friction angle were given based on Mohr-Coulomb model.