摘要
波浪荷载作用下,软黏土存在刚度软化和塑性应变积累的现象。将软化指数与累积塑性应变引入到能够反应土体动力非线性的Hardin-Drnevich模型中,建立修正模型,使之能够反映软黏土体软化与塑性应变累计特性,并推广到三维,推导出由应力控制加载的增量形式;将修正Hardin-Drnevich模型与模拟波浪荷载下土体应力特征的循环耦合试验结果进行对比分析,验证该修正模型的可靠性;采用数值方法对波浪荷载作用下的海床土体应力特性进行分析,依据修正Hardin-Drnevich模型对不同位置土体单元进行了应力应变预测,并与弹塑性本构得到的应力应变关系进行对比。结果表明:一般弹塑性本构仅能够模拟软黏土的塑性应变累计的特性,而修正Hardin-Drnevich模型能够模拟软黏土的软化特性与塑性应变累计特性。
Under the influence of wave load,Soft clay occurs stiffness softening and plastic strain accumulation phenomenon.In order to describe the characteristics of stiffness softening and plastic strain accumulation,establish 3 Dmodified model and derive the incremental form which is loaded by stress control,degradation index and cumulative plastic strain is introduced into Hardin-Drnevich model which can reflect soil's dynamic nonlinear characteristics to set up modified model.The new model's reliability is verified by comparing the results of this modified Hardin-Drnevich model with the results of cyclic coupling shear tests which is under wave load simulation.Numerical method was applied to analysis the stress behavior of soil at disturbed sea bed under wale load.The soil element's stress-strain relation is predicted based on modified Hardin-Drnevich model.To compare stress-strain relation based on modified Hardin-Drnevich model with the stress-strain relation using constitutive model,the result shows general Constitutive model is only able to simulate the accumulated plastic strain characteristics of soft clay,but the modified Hardin-Drnevich model can simulate the accumulated plastic strain and softening behavior characteristics of soft clay.
