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在波浪循环荷载作用下饱和软黏土地基出现孔隙水压力升高,并导致不排水强度弱化,严重影响防波堤的承载性能。考虑静偏应力影响,基于最大孔隙水压力发展模型和正常固结软黏土不排水强度公式,推导出软黏土不排水强度随循环荷载作用次数和应力水平变化的动态折减规律。结合软黏土不排水强度动态折减规律和M-C屈服准则,在有限元软件ABAQUS上实现软黏土不排水强度循环弱化分析的数值开发和动力运算过程。运用该动力有限元方法对天津港防波堤地基软黏土的动、静三轴试验进行数值模拟运算。结果表明,最大孔隙水压力发展曲线以及循环荷载作用后不排水强度的数值预测结果与动三轴试验结果吻合良好。另外,动力有限元方法(DFEM)能够表示土体强度在循环荷载作用下的具体弱化过程。
Under the action of wave cyclic loading, the pore water pressure rises on saturated soft clay foundation, leading to the weakening of undrained strength and seriously affecting the bearing capacity of breakwater. Considering the influence of static deviatoric stress, based on the model of maximum pore water pressure and the formula of undrained strength of normal consolidated soft clay, the law of dynamic reduction of undrained strength of soft clay with cyclic loading and stress level was deduced. Based on the dynamic reduction law of undrained strength of soft clay and M-C yield criterion, numerical development and dynamic computing of cyclic weakening analysis of undrained strength of soft clay are implemented on the finite element software ABAQUS. The dynamic finite element method is applied to simulate the dynamic and static triaxial tests of soft clay in Tianjin Port breakwater foundation. The results show that the numerical results of the maximum pore water pressure curve and the undrained strength after cyclic loading show a good agreement with the moving triaxial test results. In addition, the dynamic finite element method (DFEM) can represent the specific weakening process of soil strength under cyclic loading.