隧道上台阶无人化立拱纵向连接替代方案

Replacement Scheme for Longitudinal Connection of Unmanned Arch Erection on Upper Step of Tunnel

针对新乌鞘岭隧道上台阶无人化立拱施工问题,通过定性地分析钢拱架的铆钉式连接、旋转连接及三角钢筋连接三种替代方案,选择三角钢筋连接并通过数值模拟将其与传统形式的纵向连接进行定量对比分析,验证了其力学可行性。数值模拟结果表明:两种连接方式下衬砌变形及拱架弯曲变形特征几乎一致;施作相邻两榀拱架时,下一榀需要较大的约束力,无人化立拱和传统连接方式下第二榀所需支座反力比第一榀分别提高了64.9%、59.0%;三角钢筋的应力状态较传统的连接筋更为均匀,仅拱顶局部出现应力集中现象,最大值为79.8 MPa。采用自主研发的新型钢拱架分节间卡扣连接的构造形式,根据新乌鞘岭隧道进口段断面尺寸最终将上台阶拱架形式设计为五节,拱顶拱架长7.3 m,拱腰5.7 m,拱脚1.6 m,并结合现场试验将三角钢筋优化为A形钢筋。优化后的连接方式满足喷射混凝土的回弹量与挂灰要求,现场施工效率明显提高,且具有一定的经济优势。

Aiming at the construction problem of unmanned arch erection on the upper steps of new Wushaoling Tunnel,through qualitative analysis of three alternative schemes of rivet connection,rotary connection and triangular reinforcement connection of steel arch frame.The triangular reinforcement connection was selected,and its mechanical feasibility was verified by quantitative comparison with the traditional longitudinal connection through numerical simulation.The numerical simulation results show that the characteristics of lining deformation and arch bending deformation are almost the same under the two connection modes.When two adjacent arches are constructed,the next one needs greater constrained force.Under the unmanned arch erection and the traditional connection mode,the bearing reaction force required by the second one is 64.9%and 59.0%higher than that of the first one respectively.The stress state of triangular reinforcement is more uniform than that of traditional connecting reinforcement,only local stress concentration occurs in the vault,and the maximum value is 79.8 MPa.Using the self-developed structural form of snap connection between sections of the new steel arch frame,according to the section size of the entrance section of new Wushaoling Tunnel,the upper step arch frame is finally designed as five segments,the arch frame length of vault is 7.3 m,the arch waist length of vault is 5.7 m,and the arch foot length of vault is 1.6 m.Combined with the field test,the triangular reinforcement is optimized into A-shaped reinforcement.The optimized connection mode meets the requirements of rebound amount and ash hanging of shotcrete,significantly improves the on-site construction efficiency,and has certain economic advantages.