大跨度隧道初级支护中锚杆的受力特性研究  

Research on Mechanical Characteristics of Anchor Rods in Primary Support of Large-span Tunnels

作　　者：王丙兴 

机构地区：[1]河北省高速公路邢汾管理处,河北邢台054001

出　　处：《公路交通技术》2015年第1期94-97,共4页Technology of Highway and Transport

基　　金：河北省交通厅重点科研项目(Y-2011055)

摘　　要：由新奥法隧道设计理论可知,锚杆是通过其轴向拉力来实现对围岩的加固作用的,也就是说锚杆发挥其锚固作用是利用其抗拉特性。为了深入了解高速公路大跨度隧道锚杆的实际受力特征,以邢汾高速公路邢台段某隧道为例,对其Ⅳ级围岩深埋段选定一处典型监测断面,采用现场监测的手段对锚杆的受力状态进行监测。监测结果显示:3根测力锚杆在其内部的大部分测点均承受压力。这一监测结果与理论上锚杆受拉完全相反,锚杆承受压力是不能发挥支护作用的;其余少数测点承受拉力,最大实测拉力约为7 k N,该值仅占到锚杆可承受最大设计拉力92k N的7.6%。可以认为,某隧道在该监测断面处系统锚杆发挥的抗拉性能极其有限,几乎起不到应有的支护作用,这对修改现有隧道围岩支护设计规范提供了数据支持。As shown from tunnel design theory of the New Austrian Tunneling Method,anchor rods realize the effect of reinforcing wall rocks via axial tensile force,that is,anchor bolts develop their anchor role by means of tensile characteristics. For deep understanding of the actual mechanical features of anchor rods in large- span tunnels on expressways,this paper,with some tunnel at Xingtai section of Xingtai- Fenyang Expressway as an example,selects a typical monitoring section from deeply buried sections of grade IV wall rock to monitor the stress state of anchor rods by means of site monitoring. The monitoring result shows that most of measured points inside the 3 load anchor rods bear pressure. This monitoring result is completely opposite to the tension of anchor rods in theory,and anchor rods under the pressure cannot develop supporting role; the other few measured points bear tension and the max. measured tension is approximate7 k N,which only accounts for 7. 6% of the maximum. design tension 92 k N that anchor rods can withstand. It can be regarded that the tensile performance that system anchor rods develop at the monitoring section of the tunnel is extremely limited and hardly plays the due supporting role,this can provide data support for modifying the existing code for design of wall rock support of tunnels.

关 键 词：公路隧道 现场监测 锚杆轴力 

分 类 号：U459.2[建筑科学—桥梁与隧道工程]