陡倾千枚岩地层铁路隧道结构大变形施工技术研究

Research on Treatment Technology on Large Deformation of Railway Tunnel in Steep-dipping Phyllite Stratum

文章依托新建成都——兰州铁路杨家坪隧道工程,采用理论分析与监控量测相结合的方法,研究了陡倾状千枚岩地层隧道大变形机理及其整治措施,取得了如下结论:高构造应力和陡倾节理化千枚岩,是隧道发生挤压性大变形的根本内因;隧道支护受力应力应变特征:拱部锚杆受力增长缓慢,边墙锚杆受力大,工程措施应适当加长边墙系统锚杆;在轻微大变形段,隧道采取I18钢架调整至I20b钢架,6 m长边墙锚杆对增加边墙平行陡倾岩层的整体性、防止岩层发生侧向弯折变形有很好的作用;中等大变形试验段,隧道采用系统锚杆先打后打结合、长短结合对中等大变形有非常好的控制作用。文章研究成果对软岩大变形隧道施工与设计具有一定参考价值。

Based on the newly built Yangjiaping Tunnel of Chengdu-l.anzhou Railway, the paper studied the large deformation mechanism and treatment measures of tunnel in steep-dipping phyUite stratum by combining theoretical analysis and monitoring measurement, and reached the following conclusions： the fundamental internal cause for the squeezing deformation of tunnel was high tectonic stress and steep-dipping jointed phyllite ;the tunnel supporting stress and stress-strain featured slow stress growth of anchor bolt in the arch and large stress of anchor bolt in side walls, so the anchor bolt in side walls should be properly lengthened; in slightly deformation section,the I18 steel frame was replaced by I20b steel frame and the 6-meter-long side wall anchor bolt proved helpful for increasing the integrality of paralleled steep-dipping rock strata and avoid side-direction bucking of the rock strata; in medium deformation section, the anchor bolts were struck into the wall successively in a long-short layout,which proved effective in controlling medium deformation.The research results in this paper earl provide reference for the design and construction of large-deformation tunnel in soft rock.