隧道交叉口挑顶施工动态力学响应分析研究与现场试验OA

To address the challenges of numerous construction procedures,complex stress conditions,and difficulty in controlling surrounding rock deformation at the intersection of the No.2 cross-tunnel and the main tunnel of the Qunke Tunnel on the Xi'an-Chengdu Railway,a roof-breaking excavation scheme and associated mechanical analysis are investigated.First,a comprehensive roof-breaking ex-cavation and support scheme consisting of"cross-tunnel climbing+reinforcing ring support+temporary-to-permanent support+symmetrical excavation and support"is proposed.Subsequently,a numerical model is established using Midas finite element software to finely analyze the dynamic me-chanical response characteristics and three-dimensional spatial effects of the support structure and sur-rounding rock during the roof-breaking construction process.Finally,combined with field real-time monitoring data,the analysis focuses on the stress variation characteristics of the support structure and surrounding rock at the tunnel intersection,as well as crown settlement and lateral convergence defor-mation patterns around the tunnel periphery.The results show that during construction,the stress of the primary support structure remains within the range of 0.15 MPa to 0.76 MPa,and the maximum axial force in the steel arch frame is 343 kN.This support system effectively reduces the stress and settlement deformation of the primary support induced by surrounding rock pressure.Construction of the intersection induces stress redistribution in the surrounding rock near the reinforcing ring,making this area prone to stress concentration.The maximum crown settlement at Sections 1-3 is 1.12 mm,and the maximum lateral displacement at the arch springline is 1.06 mm;both values are relatively small,indicating that the intersection remains in a stable and controllable state overall.During the ex-cavation and support process of the left-side upper bench at the intersection,the left and right arch springlines and the right arch shoulder transition from compression to tension.These locations should be closely monitored during construction,and timely support should be provided to prevent local rock-falls,ensuring that the entire construction process remains safe and stable.The research findings can provide important references for roof-breaking construction,support structure design,and surrounding rock stability control at tunnel cross-tunnel and main tunnel intersections under similar complex conditions.