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已有震害研究表明,震后边坡会因持续变形而破坏,且伴随着土体强度逐渐降低的现象,即土的循环软化行为。因此,有必要研究考虑循环软化的非线性动力本构模型以用于复杂条件下地震边坡稳定性分析。在已有的非线性动力本构模型基础上,提出了考虑循环软化的处理方法。同时,在FLAC~(3D)平台上实现了本构模型二次开发,并通过了理论公式与已有文献中试验数据的验证。结果表明:计算出的骨干曲线与理论公式一致,且计算出的动剪切模量比及阻尼比与试验数据吻合较好,能够克服Hardin-Drnevich模型和Davidenkov模型在较大应变处(>0.01%)过高地估算阻尼比的缺陷;考虑了循环软化后,计算出的剪切强度有明显降低,且当遇到骨干曲线剪应力可以连续地过渡到软化后的主干曲线上,模型的收敛性较好。所开发的本构模型可为大应变条件下软土场地及边坡地震灾害评估提供支持。
Research on earthquake damage has shown that after the earthquake, the slope will be destroyed due to the continuous deformation and accompanied by the gradual decrease of soil strength, that is, the cyclic softening behavior of soil. Therefore, it is necessary to study the nonlinear dynamic constitutive model considering cyclic softening for seismic slope stability analysis under complex conditions. On the basis of the existing nonlinear dynamic constitutive model, the treatment method considering cyclic softening is proposed. At the same time, the secondary development of the constitutive model was realized on the FLAC ~ (3D) platform, and the theoretical formula and the test data in the existing literature were verified. The results show that the calculated backbone curve is consistent with the theoretical formula, and the calculated dynamic shear modulus ratio and damping ratio are in good agreement with the experimental data, which can overcome Hardin-Drnevich model and Davidenkov model at larger strain (> 0.01 %) Is too high to estimate the damping ratio of defects; considering the cycle softening, the calculated shear strength decreased significantly, and when faced with the backbone curve shear stress can be continuous transition to the softened trunk curve, the convergence of the model better. The constitutive model developed can provide support for the seismic disaster assessment of soft soil sites and slopes under large strain conditions.