绿片岩多轴受压应力松弛试验研究

Stress relaxation tests on green schist specimens under multi-axial compression

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了不同应力水平下的单轴和和双轴压缩应力松弛试验,并提出了经验拟合方程。研究结果表明:当进行单轴压缩应力松弛试验时,轴向应力呈阶梯式下降特征,这主要是由新微观裂纹的产生或者已有裂纹的扩展而引起的;双轴压缩状态下,若进行轴向应力松弛试验时,轴向应力松弛曲线呈阶梯式下降特征,侧向应变则呈阶梯式上升特征,若进行侧向应力松弛试验时,侧向应力松弛曲线呈阶梯式下降特征,轴向应变则呈阶梯式上升特征,若同时进行轴向和侧向应力松弛试验时,轴向与侧向之间的相互影响比较明显,轴向应力和侧向应力最终均无法趋于平稳值。采用经验方程对试验曲线进行拟合分析时,拟合曲线与试验曲线之间吻合得比较理想,说明采用该经验方程分析是合适的。

The biaxial stress relaxation tests on green schist under different stress levels from the auxiliary tunnel at Jinping Second Stage Hydropower Station are carried out by using biaxial creep machine,and an empirical fitting equation is put forward.The research results show that the axial stress descends in step form with fixed axial strain under uniaxial compression,which is the result of new crack occurrence and pre-existing crack propagation.The axial stress descends and the lateral stain ascends in step form when the axial stress relaxation tests under biaxial compression are carried out,and the lateral stress descends and the axial stain ascends in step form when the lateral stress relaxation tests under biaxial compression are carried out.Meanwhile,the axial and lateral stresses have much influence on each other when the axial and lateral stress relaxation tests are carried out simultaneously.The curves of the empirical equation agree with the test ones;therefore the empirical equation is available and reasonable.