多因素作用下隧道衬砌内力随时间变化规律

针对隧道初期支护和二次衬砌施作间隔时间短的工程特点，为掌握类似条件下衬砌受力变化的规律，分析二次衬砌钢筋轴力监测数据及相应的施工工况，研究隧道开挖、围岩蠕变、隧道衬砌刚度等因素对二次衬砌钢筋轴力变化的影响，如二次衬砌钢筋轴力变化曲线可分为2个明显的双曲线变化阶段：第一阶段主要受隧道开挖和隧道衬砌刚度的影响，围岩蠕变明显，在其作用下二次衬砌钢筋轴力明显增加，且轴力变化至少在1年后才趋于稳定，第一阶段大约持续33d，此阶段隧道衬砌刚度基本形成，而后二次衬砌钢筋变化进入第二阶段；第二阶段变化主要受围岩蠕变的影响。

Study on Time-dependent Variation Rules of Internal Force of Tunnel Lining under Influence of Several Factors

The secondary lining of the mentioned tunnel is cast shortly after the installation of the preliminary lining. In order to investigate the variation rules of the internal force of the tunnel lining, the influence of tunnel excavation, surrounding rock mass creeping and tunnel lining rigidity on the axial force of the re-bars in the secondary lining is studied on basis of the axial force monitoring records and construction records. The variation of the axial force of the re-bars in the secondary lining can be divided into two stages, which meet the hyperbolic rule. In the first stage, the variation of the axial force of the re-bars in the secondary lining is mainly affected by the tunnel excavation and the lining rigidity. The axial force increases significantly and reaches stable in one year because of the significant creeping of the surrounding rock mass. The first stage lasts for 33 days before the rigidity of the tunnel lining is formed. Then the variation of the axial force enters the second stage. In the second stage, the variation of the axial force of the re-bars in the secondary lining is mainly affected by the creeping of the surrounding rock mass.