泥岩夹砂岩地层隧道底鼓原因分析及整治技术

Analysis of Causes and Remediation Techniques for Tunnel Bottom Drumming in Mudstone Sandstone Stratum

某高铁隧道全长10649 m,洞身穿越白垩系下统泥岩、泥岩夹砂岩地层。2014年至2016年,隧道进口端泥岩夹砂岩局部段落隧底出现不同程度上拱、无砟轨道道床板与隧道仰拱填充之间离缝等问题,根据病害情况及工期要求,先后采取仰拱返工、钻孔灌注桩(锚杆)加固和离缝注浆封闭等措施进行了整治;2016年整治完成后,局部段落隧底上拱仍在缓慢持续发展。根据补充钻探、取样试验结果,分析为隧底长期积水使泥岩浸泡软化、吸水膨胀,层状软岩蠕变、水平构造应力和隧道结构薄弱等因素所致。结合前期整治情况,利用线路检修时机,采取拆换仰拱、调整仰拱曲率、底部增设钢架等措施进行了整治。2020年整治完成后,轨检小车连续监测结果显示轨道几何状态良好,达到了预期效果。

This paper focuses on a high-speed railway tunnel,which has a total length of 10649 meters and traverses the mudstone and mudstone-sandstone strata of the Lower Cretaceous System.From 2014 to 2016,the tunnel bottom at the inlet end,comprised of mudstone and sandstone strata,exhibited varying degrees of up-arching,as well as issues such as separation between the ballast track bed plate and the filling of the tunnel's up-arched sections.Based on the condition of the defects and schedule requirements,remedial measures including reworking of the elevated arch,reinforcement with drilled piles(anchors),and grouting to seal voids were implemented sequentially.After the completion of the remediation in 2016,the up-arching at localized sections of the tunnel bottom continued to slowly develop.According to the results of supplementary drilling and sampling tests,it is analyzed to be caused by the long-term water accumulation at the tunnel bottom,which makes the mudstone soaked and softened,absorbing and expanding water,the creep of layered soft rock,the horizontal tectonic stress and the weak tunnel structure,and other factors.On the basis of previous remediation efforts,remedial measures such as dismantling and replacing the elevated arch,adjusting the curvature of the elevated arch,and installing additional steel frames at the bottom were implemented using the line maintenance timing.After the completion of remediation in 2020,continuous monitoring results from track inspection trolleys showed that the track geometry was in good condition,achieving the expected outcomes.