新建复线隧道上跨既有隧道近接施工影响研究OA

In order to deeply explore the scope of impact of proximity construction of new tunnels and ensure the operational safety of existing tunnels,this study employed finite difference simulation software FLAC3D to construct a 3D numerical model,based on the background of a new double-track tunnel in close proximity to the existing tunnel project in southwest region.By introducing displacement and stress control standards and using core evaluation indicators such as lining vertical displacement,maximum and minimum principal stresses,and track bed displacement,a systematic analysis was conducted on the proximity effects of different excavation spacings on the existing tunnels,thereby defining the impact scope.The results show that the displacement and stress of the tunnel structure are minimal when the excavation spacing of 6 m is adopted for the sub-section tunnel face,with the existing tunnel structural displacement reduced to 0.54 mm and the maximum tensile stress maintained at 0.65 MPa,both meeting control requirements.Numerical calculations show that the 30 m range before and after the intersection constitutes the critical stage for deformation growth in the existing tunnels,during which the maximum track bed vertical displacement reaches 0.21 mm and lining structural displacement peaks at 0.47 mm(concentrated in the arch waist area).Beyond this range,the proximity construction effects gradually diminish.This study confirms that rational selection of excavation methods and advance rates can significantly reduce proximity disturbances from new tunnels to existing ones,providing scientific references and engineering insights for similar tunnel proximity construction projects.