考虑含水率的红层泥岩蠕变特性及改进伯格斯模型

为揭示西南地区广泛分布的红层泥岩在不同含水条件下的蠕变特性，采用YSJ-01-00岩石三轴流变试验机进行三轴压缩蠕变试验。试验结果表明，（1）随着含水率的升高和轴向荷载的提升，蠕应变量与瞬时应变量的比值整体上都呈增大趋势，比值范围为0.117～0.985，平均比值维持在0.348～0.480之间；（2）红层泥岩的初始、稳态和极限加速蠕变速率都随含水率的升高而增大；（3）红层泥岩的长期强度随含水率的上升而降低，量化比较发现红层泥岩的非线性蠕变程度随含水率的上升而越得到体现。研究了红层泥岩蠕变的非线性特征，提出一个黏弹性模量 ，并引入一个非线性黏塑性体，建立一个新的改进后的伯格斯（Burgers）模型。基于BFGS算法和通用全局优化法对蠕变试验曲线进行辨识，确定模型参数，并进行模型可靠性分析，验证了所建模型的正确性和合理性。

Improved Burgers model for creep characteristics of red bed mudstone considering water content

In order to reveal the creep characteristics of red bed mudstone with wide distribution in Southwestern China under different water content conditions, the rock triaxial creep testing machine YSJ-01-00 is used to carry out the triaxial compressive creep test. Experiment results show that: (1) On the whole, with increasing of water content and the lifting of the axial load, the ratio of creep strain and instantaneous strain is increasing. Also, the ratio range is 0.117-0.985, and the average ratio is maintained at 0.348-0.480. (2) The initial, steady and ultimate accelerated creep rate increase with the rise of water content. (3) The long-term strength of red bed mudstone decreases with the rise of water content. By quantitative comparison, it is found that the nonlinear creep degree of red bed mudstone is more obvious with the increase of water content. Therefore, in the construction of important project, the influence of water content on the creep characteristics of red bed mudstone should not be neglected. Based on the nonlinear characteristics of red bed mudstone, a viscoelastic modulus is proposed; and a new improved Burgers model is established by introducing a nonlinear viscoplastic body. Based on the BFGS algorithm and the general global optimization method, the creep test curves are identified; the model parameters are determined; and the reliability of model is analyzed; and the correctness and rationality of the model are verified.