基于改进西原模型巷道围岩流变参数反演分析

当应力达到一定水平时,岩石经过衰减和稳定蠕变过程之后会发生加速蠕变破坏,但是传统西原体模型无法更有效地反映该加速蠕变阶段。为了解决这一问题,引入一个非线性流变元件,并将其串联在西原体模型上,组成一个新的六元件模型,该模型可充分反映岩石蠕变的三个阶段。基于改进的西原体模型本构方程,应用Laplace变换,得到了盾构圆形巷道围岩的径向位移变化规律;根据巷道围岩收敛变形现场实测数据,反演得到了岩石黏弹塑性蠕变参数;由巷道围岩径向位移计算结果和实测数据对比分析表明:两者吻合较好;当t ≤25 d时,巷道围岩处于加速变形阶段,其径向位移变化速率随时间的增长而不断增加,当t>25 d时,巷道围岩进入稳定变形阶段,随时间的推移,其径向围岩位移变化速率逐渐趋于稳定。

RHEOLOGICAL PARAMETER INVERSION AND ANALYSIS OF ROADWAY SURROUNDING ROCK BASED ON MODIFIED NISHIHARA MODEL1)

When the stress reaches a certain level, the rock would undergo accelerated creep failure after the attenuation and stable creep processes, but the traditional Nishihara model could not reflect the accelerated creep stage effectively. In order to solve this problem, a non-linear rheological element is introduced and connected in series to the traditional Nishihara model to form a new six-element model, which could fully reflect the three stages of the rock creep. Based on the improved constitutive equation of the Nishihara model and the Laplace transformation, the variations of the radial displacement of the surrounding rock of the shield circular roadway are obtained. Based on the measured data of the convergence deformation of the surrounding rock of the roadway, the viscoelastic-plastic creep parameters of the rock are obtained by inversion. The comparison between the calculation results of the radial displacement of the surrounding rock and the measured data shows that when $t\leq 25$ d, the surrounding rock of the roadway is in the stage of the accelerated deformation, and the rate of change of the radial displacement is increased with time; the surrounding rock of the roadway enters the stage of the stable deformation when $t>25$ d, and the rate of change of the displacement of the radial surrounding rock is gradually stabilized with the passage of time.