Abstract

Under the long-term effect of high stress, the stability problem caused by the time-dependent deformation of brittle surrounding rock in deep engineering is becoming more and more prominent. The accurate description of the effectiveness of brittle rock is an important basis for the prediction of mechanical response and the stability evaluation of surrounding rock in deep engineering. To describe the accelerated time-dependent deformation behavior of brittle rock, a Newtonian body with non-constant parameters considering the effects of stress state is proposed. Combined with the improved Burgers model, a viscoelastic model with non-constant parameters of brittle rock is developed. The effects of time, delay coefficient, and stress level on the viscosity coefficient, as well as the influence of delay coefficient and initial viscosity coefficient on the accelerated time-dependent deformation, are examined. The results show that (1) the viscosity coefficient decreases with time and increases with the delay coefficient, while the attenuation rate increases; (2) the viscosity coefficient decreases with increasing stress level, and its attenuation rate increases with time; (3) with the increase of the delay coefficient, the nonlinear characteristics of the accelerated phase of the rock time-dependent deformation curve become more and more obvious; and (4) as the initial viscosity coefficient increases, the nonlinear characteristics of the accelerated phase of the time-dependent deformation curve become less and less obvious. The above laws fully reflect the evolutionary law of the nonlinear time-dependent deformation of rock. By comparing the results of the marble creep test with theoretical predictions, we found that when the stress limit is exceeded, the established model can well describe the initial attenuation, steady state, and accelerated characteristics of the rock time-dependent deformation curve, thus verifying the ability of the proposed model to describe the accelerated creep behavior, as well as the overall rationality of the model.

摘要

在长期高应力作用下，深部工程脆性围岩时变变形引起的稳定性问题日益突出。准确描述脆性岩石的有效性，是深部工程围岩力学响应预测和稳定性评价的重要依据。为了描述脆性岩石的加速时变变形行为，提出了考虑应力状态影响的非恒定参数牛顿体。结合改进的Burgers模型，建立了脆性岩石参数不定值的粘弹性模型。时间、延迟系数和应力水平对粘度系数的影响，以及延迟系数和初始粘度系数对加速时变变形的影响，进行了检查。结果表明：（1）黏度系数随时间减小，随延迟系数增大而增大，而衰减率增大；(2)粘度系数随应力水平的增加而减小，其衰减率随时间增加；(3)随着延迟系数的增大，岩石时变曲线加速相的非线性特征越来越明显；(4)随着初始黏度系数的增大，时变曲线加速相的非线性特征越来越不明显。上述规律充分反映了岩石非线性时变变形的演化规律。通过将大理岩蠕变试验结果与理论预测结果进行对比发现，当超过应力极限时，所建立的模型能够很好地描述岩石时变变形曲线的初始衰减、稳态和加速特性，从而验证所提出的模型描述加速蠕变行为的能力，以及模型的整体合理性。