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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,且伴随着强度逐渐降低的现象,即土的应变软化行为。因此,有必要研究非线性应变软化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基础上,提出了考虑应变软化的处理方法。在FLAC3D平台上实现了非线性应变软化动力本构模型的二次开发,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;考虑了应变软化后,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。开发的非线性动力软化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 the intensity, that is, the strain softening behavior of the soil. Therefore, it is necessary to study the nonlinear strain softening dynamic constitutive model for seismic slope stability analysis under complex conditions. Based on the existing nonlinear dynamic constitutive theory, a new method to deal with strain softening is proposed. The secondary development of nonlinear strain softening dynamic constitutive model is realized on FLAC3D platform, and the theoretical formula and the test data in the existing literature are 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 %) Overestimates the defect of the damping ratio; the calculated shear strength is significantly reduced after strain softening is taken into account, and the convergence of the model is obtained when the shear stress of the backbone curve can be continuously transferred to the softened trunk curve better. The developed nonlinear dynamic softening model can support the evaluation of earthquake disaster of soft soil site and slope under the condition of large strain.