岩石非定常蠕变模型辨识

IDENTIFICATION OF NON-STATIONARY CREEP CONSTITUTIVE MODELS OF ROCK

在页岩蠕变试验数据基础上,分析岩石黏弹性变形随应力水平不同和时间发展的变化规律。通过反分析方法建立一维情况下非定常黏弹性模型的蠕变方程,通过应变的理论计算结果与试验结果的对比发现,不考虑参数的时间相关性将引起较大的误差,而考虑参数的时间相关性的非定常黏弹性模型比定常黏弹性模型可更为准确地反映岩石的黏弹性变形性能。在软岩巷道二维非定常蠕变模型辨识的工程实例中,事先假定围岩为黏弹性和黏弹塑性两种不同力学模型,并分别考虑参数为定常和非定常两种情形,在已知现场量测位移条件下,利用位移反分析并根据一定的准则函数求其不同模型中的参数及相应的准则函数值,由各个模型相应的准则函数值大小,判定最佳模型。在假定的一组模型里,发现非定常黏弹塑性模型为最佳模型。

Based on the creep experimental data of shalet,he relationship among stress levelt,ime and viscoelastic deformation disciplines of rock is analyzed.One-dimensional viscoelastic creep equation of rock is given by back analysis method.According to theoretical and experimental data,large errors will be encountered without considering time-dependent behaviors of the parameters.Therefore,a non-stationary viscoelastic constitutive model can more accurately reflect the deformation behaviors of rock than those of stationary mode.The necessity of non-stationary parameters is testified.In practical cases,the surrounding rocks in a certain tunnel are supposed to be viscoelastic and visco-elastoplastic bodies,respectively;and certain parameters of rocks are regarded as time-dependent variables.By using back analysis of displacement,two-dimensional non-stationary creep constitutive model of the surrounding rock is identified based on measured displacements.The result indicates that the visco-elastoplastic model with non-stationary parameters can reflect the characteristics of rock mass objectively.