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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E(ω),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。
In order to reveal the creep characteristics of widely distributed red mudstone in southwestern China under different water conditions, triaxial compression creep test was carried out by YSJ-01-00 rock triaxial rheometer. The experimental results show that: (1) With the increase of moisture content and axial load, the ratio of creep strain to instantaneous strain increases as a whole, with the ratio range of 0.117 ~ 0.985 and the average ratio of 0.348 ~ 0.480; (2) The initial, steady state and ultimate accelerated creep rates of red mudstone all increase with the increase of water cut; (3) The long-term strength of red mudstone decreases with the increase of water cut, The quantitative comparison shows that the nonlinear creep of the red mudstone is reflected with the increase of water cut. The nonlinear characteristics of red mudstone creep are studied, a viscoelastic modulus E (ω) is proposed, and a nonlinear viscoplastic body is introduced to establish a new improved Burgers model. Based on the BFGS algorithm and the global optimization method, the creep test curve is identified, the model parameters are determined, and the model reliability analysis is carried out. The correctness and rationality of the model are verified.