【摘要】 既有隧道受下方盾构施工影响较大，易出现不均匀沉降，导致隧道开裂、渗水等问题。现有的研究大多针对过大椭圆率引发隧道损伤而进行加固，从而控制变形进一步发展，针对盾构下穿施工前预加固措施的加固效果研究较少。基于南京地铁6号线工程，采用数值模拟与施工监测相结合的方法探讨工字钢钢环预加固工况下管片环横向弯曲刚度提升规律及水平收敛变形控制效果。研究结果表明：(1)管片环内侧钢环的高度、钢环与管片接触面贴合程度对管片环弯曲刚度有效率和水平收敛变形的影响较大；(2)当采用高180mm工字钢对既有隧道进行预加固，且保证工字钢与管片贴合紧密时，管片环弯曲刚度有效率相对于未加固工况提高约73.3%,隧道水平收敛变形相对于未加固工况减小约26.5%;(3)南京地铁6号线采用高180mm工字钢对既有隧道进行预加固处理，其拱底沉降最大值为11.7mm,管片环水平收敛变形最大值仅为1.4mm,钢环加固后管片保持了较好的真圆度且未出现裂缝。更多还原

【Abstract】 The existing tunnel is greatly affected by the shield tunnelling underneath,which is prone to uneven settlement,leading to tunnel cracking,water seepage and other problems.Most of the existing studies aimed at the tunnel damage caused by excessive ellipticity and the ring reinforcement measure is to control deformation development,and less discuss the pre-reinforcement effect before shield tunneling underneath.Based on the project of Nanjing Metro Line 6,the method combining numerical simulation and construction monitoring was used to discuss the horizontal bending stiffness improvement law and the deformation control effect of the pre-reinforced existing tunnel.The results show that:(1) The height of the steel ring inside the segment ring and the bonding degree of the steel ring and the contact surface of the segment have a great influence on the bending stiffness efficiency and horizontal convergence deformation of the segment ring;(2) When the existing tunnel is pre-reinforced with 180 mm I-steel,and ensure that the I-steel and the segment close,the effective bending rigidity ratio of the ring is about 78.0% higher than the unreinforced ring condition,and the horizontal convergence deformation of the tunnel decreases by about28.0%;(3) After Nanjing Metro Line 6 uses 180mm I-steel to pre-reinforce the existing tunnel,its maximum arch bottom settlement is 11.7 mm,the horizontal clearance convergence of the ring is only 1.4 mm,and the pre-reinforced steel ring maintains a good true roundness and no cracks.更多还原