自进式管棚施工技术在软弱围岩隧道中的应用

Application of Construction Technique of Self⁃drilling Pipe Shed in Tunnel with Soft Surrounding Rock

针对传统管棚在软弱围岩段施工时易塌孔、送管困难等难题,以郑万铁路高家坪越岭隧道为工程实例,建立简支梁模型,对R51×10自钻式锚杆作管棚替代Φ76×6钢花管管棚的可行性进行了分析。结果表明:自进式管棚的抗剪强度和抗弯强度分别达到236.41,118.2 MPa,满足支护设计要求。采用自进式管棚对不同隧道Ⅴ类围岩段施工跟进2 043 m,施工效率达1.42 m/min,整体效益较钢花管管棚支护提高22%。以直径减少33%的自进式管棚替代钢花管管棚,在保证围岩支护安全的同时可提高施工效率、降低劳动强度,解决软弱围岩隧道的施工问题。

In view of the problems of hole collapse easily and pipe delivery difficulty using the traditional pipe shed to reinforce weak surrounding rock,taking the Gaojiaping cross ridge tunnel of Zhengzhou-Wanzhou Railway as an engineering example,a beam model was established to analyze the feasibility of pipe shed using R51×10 self-drilling anchor to replacedϕ76×6 steel pipe.The results show that,the shear strength and bending strength of the self-drilling pipe shed are 236.41 MPa and 118.20 MPa respectively,which meet the requirements of supporting design.By tracking 2043 m in the construction of class V surrounding rock section of different tunnels using the self-drilling pipe shed,the construction efficiency reaches 1.42 m/min,and the whole benefits increase by 22%comparing to the steel pipe shed support.Using self-drilling pipe shed with diameter reduced by 33%instead of steel pipe shed,which can not only ensure the safety of surrounding rock support,but also improve the construction efficiency,reduce labor intensity and solve the construction problems of tunnel with soft surrounding rock.