隧洞围岩收敛损失位移的求取方法及应用

隧洞围岩变形监测断面设置与开挖施工工序上的先后导致了损失位移问题，它对于判断围岩的变形状态、评价其稳定性具有重要的意义。复杂多变的围岩条件使基于收敛曲线的累积位移和增量位移参数反演方法的应用变得非常谨慎。针对这些问题，通过对一致性问题的讨论后认为，虽然变形演化规律上的一致性尚存在问题，但三维计算和现场围岩的总位移之间的一致性是可以保证的。以此问题为前提，以Hoek经验公式的通式为基础，依据规范规定，基于现场监测收敛位移曲线，建立了损失位移的求取步骤，并将其在锦屏II级水电站辅助洞A、B围岩变形规律分析中进行了应用，得出了两个监测断面各测线的最终监测位移收敛值、损失位移、总收敛位移和相对收敛值等，拟合而得的全收敛曲线与监测曲线相吻合，能够很好地描述现场围岩随空间效应变化的演化规律，为围岩稳定性评价和基于全位移的参数反演分析奠定了基础。

Method of obtaining loss convergence displacement and its application to tunnel engineering

The loss convergence displacement is induced by the constructing procedure of the monitored section and tunnel. And it is of great value to identification of the deformation state and evaluation of stability of surrounding rock mass. Application of experiential analogy method is considered lacking in reliability due to the challenging condition of surrounding rock mass. And the consistency in the evolving rule of convergence displacement obtained by the three-dimensional simulation and field monitoring is not universal. So it should be discussed before application of the mechanical parameters back analysis methods based on convergence curves. But so far the consistency in total convergence displacement can be ensured. Based on this premise, a method of obtaining loss displacement is presented, in which the Hoek experiential formula is applied and some provisions in specification are cited as the support. Finally this method was carried out in the analysis of deformation rule of surrounding rock mass in Auxiliary Tunnel A and B in Jinping II Power Station. The final monitored displacement, loss displacement, total convergence displacement and relative convergence displacement are obtained. And the good agreement of the fitting curves with the monitored ones shows that this method is rational in obtaining the evolving rule of displacement of surrounding rock mass with the space effect. Furthermore, this method is an important foundation for the evaluation of stability of surrounding rock mass and the back analysis of mechanical parameters.