The double side-drift method used in super-large cross-section loess tunnels is slow in tunneling advance and costly.To address these challenges,a case study is conducted on the expansion and reconstruction project of the Fenghuangshan tunnel from Qingshuiyi to Zhonghe section of the G30 Lianyungang-Khorgos expressway,and a five-step single side-drift method is proposed.The surrounding rock's deformation and streel arch's stress when employing the double side-drift,five-step single side-drift,conventional single side-drift,and bench methods are comparatively analyzed.Finally,the feasibility of the five-step single side-drift method for constructing the Fenghuangshan tunnel is validated through field monitoring data.The results reveal the following:(1)The crown settlement and horizontal convergence of the five-step single side-drift method are 3.59 cm and 1.31 cm lower than those of the conventional single side-drift method and 1.4 cm and 0.59 cm higher than those of the double side-drift method.The stress of the steel arch is less than that of the double side-drift method except for the arch shoulder,with a maximum reduction of 70 MPa.The ratio of the maximum stress of the steel arch to the steel yield strength is 0.04 higher than that of the double side-drift method and 0.08 lower than that of the single side-drift method.(2)The traditional single side-drift method is less safe than the five-step single side-drift method.The improved five-step single side-drift heading method,compared with the double side-drift method,can accelerate construction progress and reduce construction costs while controlling surrounding rock deformation.(3)The optimal position of the partition wall in the five-step single side-drift method is 0.45 times the hole width in the Fenghuangshan tunnel and should be adjusted based on actual conditions for further application.
关键词
特大断面黄土隧道/五步单侧壁导坑法/数值模拟/现场试验
Key words
super-large cross-section loess tunnel/five-step single side-drift method/numerical simulation/field monitoring
维普
万方数据