Tunnel Construction Optimization with Long Steplength Based on Large-scale Mechanization
The existing construction safety steplength regulations mainly stem from the engineering experience and theoretical achievements of manual drilling and blasting method tunnels,which are difficult to match with large-scale mechanized equipment,and also restrict the development of mechanized construction technology for highway tunnels.Based on the Wuhan-Shenzhen expressway lotus tunnel project,the large-scale mechanized equipment supporting scheme suitable for Class III and Class IV surrounding rocks was proposed,which consisted of the three-arm arch installation machine,fully automatic wet spraying machine,self-propelled hydraulic inverted arch bridge,etc.The required long steplengths for various mechanical equipment construction were determined.The three-dimensional numerical simulation technology was used to compare and analyze the deformation rules and plastic zone distribution characteristics of standard steplength and required steplength for large-scale mechanized equipment construction(referred to as large machine steplength)under two working conditions.Conduct on-site monitoring of the deformation of surrounding rock and structural stress characteristics of large-scale mechanized equipment after the required steplength construction.The result indicates that when using large-scale mechanized equipment for construction,the initial support enclosed loop steplength is not more than 55.0 m;the inverted arch steplength is not more than 93.0 m;and the second lining step length is not more than 151.0 m;far beyond existing specifications.Compared with the standard steplength numerical working condition,the surrounding rock settlement and uplift values under the large machine steplength working condition are larger,but the maximum settlement value is still smaller than the reserved deformation amount of equipment.After the construction with large-scale mechanized equipment at the proposed steplength,it is found that at on-site monitoring,the maximum settlement value of arch crown is less than 15.0 mm;and the maximum horizontal convergence values of arch waist and side walls are less than 12.0 mm and 8.0 mm respectively,remaining within the design allowable range.This further verified the construction feasibility and safety of large-scale mechanized equipment under the optimized long steplength.
NETL
NSTL
万方数据
