循环荷载下滨海软粘土累积塑性应变试验研究

摘要

Under the cyclic loading such as waves, the excessive settlement and deformation of soft clay affects the stability of the upper structure. Cyclic triaxial tests on muddy clay from Yantai Port were performed, and then the cumulative plastic strain variation of littoral soft clay under multiple factors, such as confining pressures, devia⁃tor stresses, dynamic stresses and cycle times, have been studied. It has been found that the cumulative plastic strain increases with the increase of cycle times, and it′s fast at the beginning, then slows down, finally achieves sta⁃bility. The cumulative plastic strain is not influenced by the confining pressures obviously, but with a larger deviator stress ratio and a larger dynamic stress ratio, its initial growth is larger, and its final stable value is larger. Accord⁃ing to the test results, a hyperbolic model of the cumulative plastic strain under multiple factors, such as confining pressures, deviator stresses, dynamic stresses and cycle times, has been put forward. Then the model was applied in⁃to Yantai Port engineering, and the results consisted with the engineering.%近海工程在波浪等循环荷载的作用下，地基中的软粘土会产生较大的沉降和变形，影响上部结构的稳定性。本文以烟台港的淤泥质粘土为研究对象，进行动三轴试验，以围压、静偏应力、动应力、荷载循环次数等为变量，探讨了不同工况下淤泥质粘土的累积塑性应变发展规律。试验结果表明，累积塑性应变随着荷载循环次数的增加，先迅速增大，而后增速减缓，最终应变值趋于稳定；累积塑性应变受不同围压值的影响不明显，但是静偏应力比、动应力比越大，其初始增速越快，最终达到的稳定值越大。通过试验结果分析，综合考虑围压、静偏应力、动应力、荷载循环次数等影响因素，提出能够合理描述累积塑性应变发展规律的双曲模型，并应用于烟台港实际工况，计算结果符合工程实际。