Study On Surface And Building Foundation Deformation Induced By Metro Shield Construction And Its Control Technology

Studyon the laws of surface deformation caused bythe tunnel shield construction and howto control the nearbysurface structures deformation has important theoretical significance andimportant application value in the Xi’an loess area. Based on Xi’an subwayline three from DayanPagoda to Beichi Tou, using theoretical analysis, numerical simulationand engineering practice tostudy. The major work and conclusions as follows:(1)Combined with the ground settlement caused by earth pressure balance shield tunnelling,it is concluded that the main factors affecting the surface subsidence are:properties of layer,construction method,tunnel depth,the form and size of upper load, section form and size of tunnel,the forms of the supporting structucres and construction management etc. Surface deformationcaused bysoil deformation which is around the building foundation, then effect building structuredeformation, building depends mainlyon foundation stiffness to resistance deformation of soil,proposed the effects of shield tunnel construction basis of different buildings.(2)With the numerical simulation software named FLAC, Surface deformation in normalconstruction process was predicted. The prediction results show that building settlement was solarge that it exceeded the allowable deformation values when reinforcement measures wasn’t beused in construction process.(3)Based on peck theory, control measures of surface and building deformation induced byshield construction were put forword.Combined with the actual situation from DaYan Pagoda toBeiChi tou, Surface deformation allowable values induced byshield construction was formulted.(4)Combining geological structure in the section, corresponding deformation controltechnologyon construction process was put forward:sleeve valve barrel grouting,to ensure shieldsteadyprogress byreducing shield construction speed, enhancing amount of synchronizationgrouting,amount of hoop supplement pulp,to ensure distance along tunnel trend of two shield machine shield construction technology and so on.(5)Making corresponding deformation monitoring scheme according to actual fieldconditions,comparison on monitoring and calculating date,the results showed that,deformation ofthe building on construction process was been controlled within the allowable range bymeans ofconstruction technologyimprovement.