利用岩石双轴流变试验机对锦屏二级水电站辅助洞的绿片岩进行不同加载路径、不同应力水平下的双轴压缩蠕变试验,将一维Burgers模型推广到双轴受压状态,对试验曲线进行辨识。结果表明,轴向和侧向的蠕变规律与加载方式有很大关系,当以定侧压比同时加轴向和侧向荷载时,轴向和侧向应变基本随荷载的增加而增加,而采用定侧压的加载方式时,侧向应变则随轴向荷载的增加而逐渐减小。采用Burgers模型拟合试验曲线时,其理论值与试验结果比较接近,因此,Burgers模型比较适合描述绿片岩的黏弹性流变特征,研究得到的双轴压缩蠕变参数也可供锦屏二级水电站深埋隧洞的设计参考。
The biaxial compression creep tests on greenschist specimens from auxiliary tunnel of Jinping II Hydropower Station were carried out. There were many kinds of loading paths and many different stress levels in the tests. The one-dimensional Burgers model was developed into biaxial compression state. And the creep parameters of greenschist under biaxial compression were determined by Burgers model. The results show that the loading path has important effect on the axial and lateral creep laws. If the axial and lateral loads are exerted simultaneously with fixed ratio, the axial and lateral strains will ascend with increasing axial and lateral stresses. But if the axial load is exerted gradually with fixed lateral stress, the lateral strain will descend with increasing axial stresses. The comparison between Burgers model and experimental curves shows that Burgers model is applicable for determining the viscoelastic rheological parameters of greenschist. These parameters are helpful for the design of deep cavern of Jinping II Hydropower Station.