三轴压缩下巷道围岩蠕变参数分析及寿命预测研究

Study on Creep Parameter Analysis and Life Prediction of Tunnel Surrounding Rock Under Triaxial Compression

为了研究不同围压作用下巷道围岩的蠕变力学特性,采用RLJW-2000流变仪开展了砂岩单轴压缩蠕变和围压为2 MPa、4 MPa、6 MPa和8 MPa的三轴压缩蠕变试验,引入一个带有长期强度和时间阈值的黏塑性损伤元件,与Burgers模型串联构建三维蠕变模型,分析了不同围压下岩石的蠕变参数演化规律。结果表明:蠕变作用下砂岩长期强度约为峰值强度的72%;建立的三维蠕变模型可以精准地描述不同围压下砂岩三轴蠕变全过程。最后,根据进入加速蠕变的应变阈值和损伤变量演化特征提出了蠕变寿命预测方法,预测结果具有较高的准确度。

In order to study the creep mechanical properties of surrounding rock under different confining pressures,the uniaxial compression creep tests of sandstone and triaxial compression creep tests with confining pressures of 2 MPa,4 MPa,6 MPa and 8 MPa were carried out.A viscoplastic damage element with long-term strength and time thresholds was introduced,and a 3D creep model was constructed in series with the Burgers model.The evolution law of rock creep parameters under different confining pressures was analyzed,and a creep life prediction method was proposed.The results showed that long-term strength of sandstone under creep is about 72%of the peak strength.The established 3D creep model can accurately describe the whole process of sandstone triaxial creep under different confining pressures.Finally,a creep life prediction method was proposed according to the strain threshold and damage variable evolution characteristics of accelerated creep,and the prediction results have high accuracy.