Research On The Mechanical Response Of Overlapped Tunnels And The Deformation Contol Of Building In Qingdao Metro Constuction

During the constuction of urban subway network,it was difficult to build new metro line when it passed across the existing tunnel,which was also an important reseach subject.Based on Qingdao Metro Project,the stress condition and deformation characteristics of ground surface,rock pillar in the overlapped zone,surrounding rock and tunnel lining were analyzed with the combination of orthogonal numerical simulation and theoretical analysis.Then eight indexes,which can not only reflect deformation characteristics but also be easily operated,were optimized,and sensitive affectors of each index were analyzed and ranked;The calculation formulas for maximum sedimentation,maximum slope angle of subsidence and settlement at the point of changing curve at the arched bottom of existing tunnel-lining's groove were put forward when new metro line passed across the existing one.The basic feature of surface deformation and the internal force variation of surface buildings caused by the construction of classical overlappped tunnel which were NO1 and No2 line of Qingdao metro were analyzed,then a series of characteristic parameters which may reflect the basic feature law mentioned above were obtained,mechanical response of the overlapped tunnels construction was simulated under different strata,excavations and reinforcement schemes,then features of deformation and destuction mechanism were analyzed.And the excavation technics and supporting methods were discussed under different strata and ground environments.Finally,suggestions for Qingdao Overlappped Tunnel Construction were put forward,such as guidelines which included stability-control of the surrounding rock and protection of the buildings,monitoring parameters,excavation method and reinforcement scheme.