深埋地下洞室群轴线方位合理布置的计算分析

Numerical analysis on proper arrangement of axis azimuth of deep underground cavern groups

给出了通过数值计算进行深埋地下洞室群轴线方位比选的方法.首先给出了基于三维非线性有限元的地下洞室开挖和支护计算方法.然后根据围岩弹性系数的分布规律,首次提出了用于轴线方位比选的开挖荷载释放系数确定方法.最后对某水电站地下洞室轴线方位的合理布置进行了计算分析.发现在洞室纵轴线与初始地应力的水平最大主应力矢量的交角较小时,适当增大交角并加强支护措施,围岩的破坏和变形可以得到限制,围岩稳定仍有保障,而进一步增大交角,围岩破坏和变形将明显增大,进一步提高支护强度对围岩稳定的改善非常有限,这为深埋地下洞室轴线方位的合理布置提供了参考.

The method to choose proper axis azimuth of deep underground cavern groups is presented. FirstlY, the calculation method to simulate the underground excavation and anchor support measures is put forward. Then, based on the distribution of surrounding rock＇s elastic coefficient, the approach to deter-mine the excavation releasing coefficient is put forward for the first time. Finally, a case study is given on the proper arrangement of the underground cavern group of a hydropower plant. It is discovered that when the angle, formed by the axis azimuth and the vector of horizontal maximum principal stress is within a small range; properly enlarging the angle has a little influence on the stability of underground caverns if correspondingly enhancing the anchor support strength. However, when further enlarging the angle, the stability of surrounding rock is unfavorable. Even higher strength of anchor support does not help to guarantee the stability when the angle is out of the rational range. This conclusion gives references to the engineering practices.