【摘要】 为探究既有隧道影响下新建四车道隧道围岩变形特性，采用FLAC 3D有限差分软件，构建Ⅴ级围岩等效岩块的单轴压缩试验模型，分析等效岩块的极限应变值，得到Ⅴ级围岩等效岩块极限剪应变和极限主拉应变。并依托麻岙岭扩建隧道工程，建立隧道二维平面模型，分析既有隧道与新建隧道的间距（0.5D、1.0D、1.5D）及强度折减系数对围岩剪应变、位移及地表沉降的影响规律。研究表明：当间距从0.5D增大至1.5D时，破坏区主要集中在新建隧道拱腰，对既有隧道影响减弱，临界安全系数提高至3.2；当间距固定时，隧道围岩位移随着折减系数的增大而增大，地表沉降最大值出现在隧道中心线上方，折减系数超过2.0后增速显著加快。最后以隧道拱顶沉降为指标，探讨了隧道Ⅴ级围岩不同间距条件下的施工安全预警标准，可为近接隧道施工安全控制提供参考依据。更多还原

【Abstract】 To investigate the deformation characteristics of surrounding rock for a newly constructed four-lane tunnel influenced by an existing adjacent tunnel, a uniaxial compression test model of equivalent rock blocks of grade V surrounding rock was established using FLAC 3D finite difference software. The ultimate strain values of the equivalent rock blocks were analyzed to determine the ultimate shear strain and ultimate principal tensile strain of the grade V surrounding rock. Based on the Ma’aoling Tunnel expansion project, a twodimensional tunnel plane model was developed to analyze the effects of varying distances(0.5D, 1.0D, 1.5D) between the existing and new tunnels and different strength reduction coefficients on shear strain, displacement of the surrounding rock, and surface settlement.Results indicate that as the tunnel spacing increases from 0.5D to 1.5D, the damage zone concentrates mainly at the arch haunch of the new tunnel, the influence on the existing tunnel decreases, and the critical safety factor rises to 3.2. With fixed spacing, surrounding rock displacement increases with increasing reduction coefficient, and the maximum surface settlement occurs above the tunnel centerline,accelerating notably when the reduction coefficient exceeds 2.0.Finally, using tunnel crown settlement as an indicator, construction safety early-warning standards for grade V surrounding rock under different spacing conditions were discussed, providing a reference for safety control in close-proximity tunnel construction.更多还原