The Study On The Interaction Between The Urban Small Space Tunnel And The Existing Air Rapid Shelters

With the rapid development of China's economy and the construction of a large number of infrastructures,cities have encountered problems such as the lack of lands and resources on urban development.Therefore,the idea of developing urban transportation systems underground has emerged.The development and utilization of underground space have become hot research interest.With the development of underground engineering,the structure of underground traffic engineering is becoming more and more complex,and the mutual influence of adjacent buildings presents greater uncertainty.Under the condition that urban tunnels and underground structures move through each other,the impact between existing buildings and newly-built structures needs to be taken into account during construction,and the influence of structural stability changes on the surrounding rocks must also be considered.Therefore,in order to better guide the engineering practice,this paper relies on the actual working conditions to study the interactive characteristics of the newly-built small clear distance tunnel and the existing sheltered tunnel.The main research content and achievements of this article are as follows:Collected summarizing the impact of urban tunnel construction on existing buildings and research status of mechanical properties of cross-tunnel construction,summarizing and analyzing the main factors affecting the existing buildings of newly built tunnels,mainly including the depth of new tunnels,new tunnels and both There are building distances,crossing angles,new tunnel excavation methods,and new tunnel support parameters.Taking the cross section of the Dahua Road tunnel and the existing shelter tunnel in the Yuzhong District of Chongqing Municipality as the construction background,the interaction between the construction of the new tunnel and the existing shelter tunnel is studied.Analyzes the net distance,crossing angle,new tunnel excavation method,excavation footage,spacing between the left and right hand planes of a small clear distance tunnel,and the construction of a small-spacing tunnel with the reinforcement of the passenger defense tunnel.The mechanical properties of the mutual influence of the cavern.During the construction of the intersection between the newly-built small-spacing tunnel and the air-defense tunnel,the new tunnel has a very significant change in the deformation and stress of the existing shelter tunnel structure.Among the several factorsstudied in this paper,the new tunnel's net distance,excavation method,and excavation footage have the most significant impact on the new tunnel and the existing shelter tunnel.The distance between the left and right hand planes of tunnels with relatively small clear-space tunnel clearances has a relatively small impact on the newly-built tunnels and the existing shelters.Through comparison of finite element analysis and on-site monitoring and measurement,it is demonstrated that the construction scheme for the small clear distance tunnel using the step method,the excavation footage of 3m,and the distance between left and right hand planes is 12 m.According to the actual finite element numerical simulation results and construction conditions,it is proposed to combine the step method construction,reduce the excavation footage,increase the spacing of the left and right hand face,and close the support structure into a ring as soon as possible to control the surrounding rock deformation in the ideal range.Inside.The backfilling and reinforcement of the passenger defense chambers with mortar and chipping stone can effectively reduce the disturbance to the surrounding rock mass,ensure the integrity of the surrounding rock,and reduce the deformation of newly-built small-spacing tunnels and air defense tunnels.