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基于三轴流变试验提出的非线性黏弹塑性流变模型存在蠕变门槛值、长期强度和非线性黏塑性体等组件。这种复杂的流变模型在进行程序实现时存在着诸多问题,比如一维的蠕变门槛值和长期强度推广至三维时难于表达、非线性黏塑性部分难于处理等问题。通过引入屈服接近度参数作为蠕变方程分段函数的判别准则,解决了三维情况下蠕变门槛值和长期强度的表达问题;详细推导了黏塑性部分的表达形式,并给出了三维中心差分形式,实现了流变模型在FLAC3D中的二次开发。通过算例验证了程序开发的正确性,对流变模型进行参数辨识,拟合曲线与试验曲线吻合较好,表明了所建模型的正确性与合理性。
The nonlinear viscoelasto-plastic rheological model based on triaxial rheological tests has creep thresholds, long-term strength and nonlinear viscoplastic components. This complex rheological model has many problems in program implementation, such as the one-dimensional creep threshold and the long-term strength when extended to three-dimensional difficult to express, non-linear viscoplastic part difficult to deal with and so on. By introducing the yield proximity parameter as the discriminant criterion of the piecewise function of the creep equation, the expression of creep threshold and long-term strength in three-dimensional case is solved. The expression of viscoplastic part is deduced in detail and the three-dimensional central difference Form, to achieve the second development of rheological model in FLAC3D. The correctness of the program development is verified by an example, and the parameter identification of the rheological model is carried out. The fitted curve is in good agreement with the experimental curve, which shows the correctness and rationality of the model.