鹰鹞山隧道衬砌纵向裂缝检测与处置对策

Lining Longitudinal Crack Detection for Yingyaoshan Tunnel and Its Treatment Measures

基于新建准朔铁路鹰鹞山隧道出入口段,通过布控量测点观测发现轨顶面往上2~4 m范围内出现不同程度的纵向裂缝,裂缝最大宽度值5.0 mm,纵向长度接近160 m,且裂缝已逐步趋于稳定。经衬砌实体钻芯取样、隧道底部钻孔探测,分析了得出了衬砌出现纵向裂缝的原因,即隧底的闪长岩在干燥状态下强度较大,但遇水容易软化,裂纹的产生与隧底纵向排水、全风化闪长岩软化及细颗粒流失有关,基底围岩承载力下降引起隧道整体下沉;二次衬砌在下沉过程中,拱部由于锚杆控制和围岩嵌固作用沉降量较小,边墙沉降位移大,导致隧道跨度最大处附近产生拉应力,出现纵向裂缝。针对分析结果,采取了隧道底部加固措施和裂缝修复措施,以防止隧底沉降影响进一步扩大。

Through observing from the measuring points,it is found that longitudinal cracks of varying degrees appear at the surface within 2 to 4 m up from the rail top in the exit and entrance section of Yingyaoshan Tunnel in the newly-built Zhunger-Shuozhou Railway. The maximum width of the cracks is 50 mm and the longitudinal length is around 160 m. The cracks gradually become stable. After entity drill core sampling from the lining,drilling detecting at the bottom of the tunnel,the reason for longitudinal crack appearing on the lining is obtained. The intensity of the diorite at the bottom of the tunnel is large in dry condition,but diorite will be easy to be soften due to met water. The appearing of cracks is attributed to longitudinal drainage at the bottom of the tunnel,and whole weathered diorite softening and lacking of fine particles.Bearing capacity of the base surrounding rock falls,which causes the overall subsidence of the tunnel. The settling amount of the arch section declines due to anchor rod control and embedded solid surrounding rock during the subsidence of secondary lining and sidewall＇s settlement and displacement is large,which generates tensile stress at the largest span of the tunnel and longitudinal cracks appear. Based on the analysis result,reinforcement measures for bottom of the tunnel and crack repairing measures have been adopted to prevent the tunnel bottom from further subsidence.