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为预测基质吸力对巴东组碎屑土夹层蠕变行为的影响,开展其非饱和蠕变经验模型的研究。基于碎屑土夹层的非饱和蠕变试验,尝试改进Singh-Mitchell蠕变模型、Mesri蠕变模型:首先选取幂函数分段描述应变-时间关系曲线的各阶段,拟合模型参数与基质吸力关系,建立包含基质吸力的改进Singh-Mitchell蠕变模型、Mesri蠕变模型;其次根据蠕变曲线特点,对应力-应变曲线、应变-时间曲线进行非线性拟合,构建包含基质吸力-应力-应变-时间的非饱和蠕变经验模型;最后对比了3种蠕变模型的预测精度。结果表明:改进的Mesri模型基本能预测碎屑土夹层的蠕变全过程,虽然当偏应力水平增高时,预测值与试验值存在偏差,但其精度基本能够满足工程应用要求;提出的非饱和蠕变模型预测效果一般,改进的Singh-Mitchell模型预测效果最差。
In order to predict the influence of substrate suction on the creep behavior of clastic interlayer in Badong Formation, an empirical model of unsaturated creep was developed. Based on the unsaturated creep test of clayey soil interlayer, we try to improve the Singh-Mitchell creep model and the Mesri creep model by first selecting the power function segments to describe the various stages of the strain-time curve and fitting the relation between the model parameters and the matrix suction , To establish improved Singh-Mitchell creep model and Mesri creep model including the matrix suction. Secondly, according to the characteristics of creep curves, the stress-strain curves and strain-time curves are fitted nonlinearly, - time unsaturated creep empirical model; and finally compared the prediction accuracy of the three creep models. The results show that the improved Mesri model can basically predict the entire creep process of clayey soils. Although the predicted values deviate from the experimental values when the deviatoric stress level increases, the accuracy can basically meet the engineering application requirements. The proposed unsaturated The creep model predicts the general effect, and the improved Singh-Mitchell model has the worst prediction effect.