冻结红砂岩非线性蠕变模型的研究

Study of nonlinear creep model of frozen red sandstone

对-10℃的冻结红砂岩进行了单轴蠕变试验,应力水平依次为0.36、0.45和0.54,发现当应力水平为0.36和0.45时,红砂岩蠕变为稳定蠕变,当应力水平为0.54时,蠕变为不稳定蠕变。应力水平越高,蠕变达到稳定的时间越长。对蠕变曲线的导函数进行分析,发现红砂岩不稳定蠕变的加速阶段门槛值为13 h。通过对实测数据的拟合,得到了3个应力水平下红砂岩蠕变的经验方程。由开尔文体、改进麦克斯韦尔体和改进陈沅江体串联组成了理论模型,并得到了模型参数,理论曲线与实测曲线吻合较好,能够较好地反映冻结红砂岩的蠕变规律。试验结果为采用冻结法施工的矿井评价冻结壁的稳定性提供了相应的参考。

An uniaxial creep test of frozen red sandstone is conducted under -10℃, and stress levels are 0.36, 0.45 and 0.54 separately.The result shows that the red sandstone creep is stable when the stress levels are 0.36 and 0.45, but the rock creep is unstable whenthe stress level is 0.54. The higher the stress level is, the longer it will take for the creep reaches stability. From the analysis ofderivative ffmction of test data, it is found that the threshold value of acceleration stage in unstable creep is the 13rd hour. Threeempirical equations of the red sandstone creep are gained by fitting the test data. A creep model is established which installs Kelvinbody, modified Maxwell body and modified CYJ body in series and gains the parameters of the model. The model curves areconsistent with test data better; so the model reveals creep discipline of frozen red sandstone. The result of creep test provides somevaluable references for the evaluation of frozen rock＇s stability in the mines that are being constructed by freezing method.