摘要
Abstract
Aiming at the contradictory problems of limited mechanical working space and construction step pitch in the construction of single-hole four-lane(double-hole eight-lane)tunnels by double sides wall heading method un-der Ⅴ-grade surrounding rock conditions,an optimization method of process based on the adaptability of mecha-nized construction was proposed.Through theoretical calculation and monitoring analysis,it was found that the in-sufficient length of the pilot pit by traditional construction methods caused a lack of operating space for large equip-ment(such as excavators and arch support installation trolleys),which is a key factor restricting the construction efficiency and safety.Based on this,the pilot pit length criterion was innovatively established with the control pa-rameters of the minimum turning radius of the machine,and the improved process of"extending the pit length to 25 m non-symmetric excavation of the direction-finding pilot pit+dynamic adjustment of the heading pitch spacing in the main tunnel"was proposed.Taking a double-way tunnel with eight lanes(with the maximum net width of 18.762 m,the maximum net height of 11.542 m,and Ⅴ-grade tuff)as the engineering carrier,a 3D numerical model was estab-lished by Midas.The comparative analysis showed that settlement at the top of of the arch by 24.6％,the convergence displacement of the side wall by 26.3％,and the redistribution effect of the internal force of the support structure was controllable(the fluctuation of axial force was less than 6％,and the peak bending moment decreased by 24.3％),which facilitated the construction by large-scale mechanized construction equipment in the optimized construction scheme.The field monitoring data verified that the scheme can significantly improve the construction stability,while shorten the cycle advance time and reduce the construction cost.The relevant research conclusions can provide some reference for the construction of similar large-span section double sides wall piolt tunnels.关键词
双侧壁施工/导坑法施工/大跨度断面/工法优化/数值仿真分析/实地监控Key words
double sides wall construction/construction by heading method/large span cross-section/optimization of construction methods/numerical simulation analysis/on site monitoring分类
交通工程
