Research On The Interaction Between Metro Tunnel And Utility Tunnel In Xi'an

With the development and utilization of underground space in China,more and more underground projects are distributed in many core areas of the city.Underground engineering construction affects not only the upper adjacent existing buildings,but also the lower part of both underground structures and other projects planned.Therefore,study of interaction between underground structures has certain academic and engineering application value.This paper summarized the theories on construction parameter selected in shield tunnel,and made some corrections to the loosening earth pressure theory on partially-developed soil arching effect.In addition,combining the Xi'an Metro Line 2 with utility tunnel,via finite element software Abaqus,modified cam-clay model and modified Drucker-Prager model based on,this paper studied the interaction of the two constructions with 3D numerical simulation.The main conclusions are as follows:(1)In the theoretical calculation of overlying pressure on the shield tunnel,for sandy soil and hard clay,when arching effect is considered,the loosening earth pressure theory on partially-developed soil arching effect can be used to calculate the soil pressure.(2)The numerical simulation of constructing double-line shield tunnels under the existing utility tunnel was carried out.The influence of construction disturbance on the existing utility tunnel was studied with the support pressure and tunnel construction method as the simulation variable respectively.The results show that the method of double line simultaneous construction in same direction can better ensure the safety of the existing utility tunnel.(3)The numerical simulation of constructing utility tunnel over the existing double-line shield tunnels was carried out.The influence of construction disturbance on the existing double-line shield tunnels was studied with the thickness-span ratio and clearance-span ratio as the simulation variable respectively.The results show that the relationship between the tunnel deformation and thickness-span ratio is inverse and linear,and the same to the relationship between deformation and clearance-span ratio.