Research On The Effect Of Existing Bridges Double Shield Tunnel Crossing In Softy Soils

Construction of metro tunnels in urban areas using shield construction method,will wear some of the buildings and bridges pile foundation,under the pile foundation will inevitably lead to the deformation of buildings and bridges.In order to study the influence of shield tunnel crossing on the reinforcement and reconstruction of bridges,at the same time,the scheme of rebuilding and strengthening bridges was studied.With the support of Fengqi Bridge under double shield tunnel of Hangzhou Metro Line 2,this paper introduces strengthening and reconstruction scheme of Fengqi Bridge and simulates double-line shield tunnel through Fengqi Bridge in advance through Midas/GTS numerical simulation software Foundation process,observing the change of bridge settlement and the force situation.Finally,before and after shield tunnel passes through bridge pile foundation,survey points are arranged and the deformation of bridge is monitored,and compared with numerical simulation.The main work and conclusion:(1)Fully understand the project of Fengqi Section of Hangzhou Metro Line 2 and be’ familiar with surrounding environment so as to make adequate preparations for reconstruction and reinforcement of Fengqi Bridge and tunnel crossing project.(2)Due to limitation of the surrounding environment,a plan for reconstruction and strengthening of Fengqiqiao has been formulated so as to ensure the safety of next two-lane shield tunnel crossing Fengqi Bridge pile foundation.The first is the cofferdam diversion bridge by high-pressure rotary jet grouting pile reinforcement,and then under the bridge construction of U-shaped structure to achieve the bridge foundation pile underpinning,U-shaped structure and the original bridge structure to bear the deck load,and finally shield Machine improvement,the implementation of shield tunnel through the bridge pile.(3)According to the plan of reconstruction and reconstruction of Fengqi Bridge,the process of double shield tunnel passing through Fengqi Bridge was simulated by Midas/GTS numerical simulation software in advance,and the force and deformation of bridge structure were observed.Under the perfect reconstruction and reinforcement scheme,the numerical simulation of Fengqi Bridge is better,which is suitable for consolidation and reinforcement project and meets economic,environmental and other benefits.(4)In order to fully understand the actual deformation situation of Fengqi Bridge,combined with the construction scheme of Fengqi Bridge reconstruction and tunneling and tunnel construction,the corresponding monitoring plan was formulated,and the site layout of measurement points was measured and measured,which provided more safety for the work Protection.After six months of actual measurement,the data were collected and analyzed,and the deformation of the bridge structure was found to be small during the whole process to meet the requirements of the code.It is a successful case of bridge reinforcement and can provide an effective reference for related engineering cases.Finally,the success of this retrofit and reinforcement program was also confirmed.