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在波浪等循环荷载的作用下,近海工程地基中的软黏土会发生强度弱化,影响上部结构的稳定性.以烟台港的淤泥质粉质黏土为研究对象,进行了动、静三轴试验,探讨不同固结静偏应力和不同循环动应力作用下淤泥质粉质黏土的循环强度弱化规律以及土体循环后不排水剪有效应力路径发展规律.通过对土体循环后不排水剪切过程中有效应力路径的分析,发现当动应力比达到0.4后,土体强度弱化趋势加快,临界有效应力比(M)减小,结构发生一定的破坏,并据此探讨了土体强度弱化机理.此外,基于等效超固结理论,在考虑偏压固结使土体初始有效应力提高的前提下,经过理论推导,得出了考虑初始固结静偏应力和循环效应的土体强度弱化公式,并通过试验数据对其进行验证.最后,通过对ABAQUS的二次开发,利用拟静力算法将该公式应用于烟台港数值模型的有限元计算中.“,”Under the action of cyclic loading of waves, the strength degradation of the soft clay beneath the offshore structures will take place, which will weaken the stability of the upper structure. A series of triaxial tests on silty clay of Yantai Port are carried out to investigate the strength degradation of the soft clay under different anisotropic consolidation stress ratios and different cyclic stress ratios. The behavior of post-cyclic undrained effective stress paths is also studied. Through the analysis of post-cyclic undrained effective stress paths, it is discovered that once the cyclic stress ratio is over 0.4, the trend of strength degradation of soils will accelerate, the critical effective stress ratio M will decrease and there will be some damage of the structure of the clay. The mechanism of strength degradation of clay is discussed. Furthermore, based on the equivalent super consolidation theory, a formula is proposed for the calculation of post-cyclic strength degradation of soils considering the increase of the initial effective stress induced by anisotropic consolidation. The formula is verified by the test results. Finally, through the secondary development of ABAQUS, it is applied to the numerical model of a breakwater in Yantai Port using the quasi-static method.