单洞双线隧道平行近接施工时效性研究

摘要

In order to investigate the timeliness impact of proximity tunnel construction to the existing tunnel under the consideration of surrounding rock rheology,through establishing numerical model,this paper analyze the changes of new tunnel in the displacement of existing tunnel,secondary lining stress and plastic zone after a certain excavation time in the background of single hole double tunnel proximity construction in Fuping.The results show:The impact on both the left and right side wall of the tunnel is greater than on the vault and invert during the construction of single hole double proximity tunnel,the maximum displacement reach 0.148 5 mm,while the crown displacement is still under de-velopment after 180 days,rear left and right side wall displacement is stable.The stress state of secondary lining is im-proved,the compressive stress is reduced after the construction of single hole double proximity tunnel,and the seconda-ry lining can remain stable over time.The excavation of new tunnels will not cause changes in the existing tunnel plastic zone,and recommend applying secondary lining of a new tunnel in the twenty-nine day which is combined with the evo-lution of new tunnels plastic zone.%以福平铁路单洞双线隧道近接施工为背景,探讨考虑围岩流变情况下近接隧道施工对既有隧道的时效性影响,通过建立数值计算模型,分析新建隧道开挖一定时间后既有隧道的位移、二次衬砌受力、塑性区的变化。结果表明：单洞双线隧道平行近接施工时,对既有隧道左右边墙的影响要大于对拱顶、仰拱的影响,右边墙最大位移达到0.1485 mm,其中仰拱、左右边墙位移稳定后,拱顶位移180 d后仍在发展；近接隧道施工后,二次衬砌受力状态得到改善,所受压应力减小,随着时间的发展二次衬砌依然能保持稳定；新建隧道的开挖不会引起既有隧道塑性区的变化,结合新建隧道塑性区演化规律,建议在第29 d左右施作新建隧道的二次衬砌。