Study On Pavement Settlement Caused By The Construction Of Parallel Double-hole Municipal Tunnels

There are many factors that affect surface settlement and deformation in the double-hole municipal tunnels project,except for the difference in soil geological conditions,buried depth of the tunnel,and the tunnel excavation method,construction parameters and vehicles in motion will cause displacement of the stratum.Factors such as the pressure on the road surface will affect the settlement and deformation of the road to a certain extent.This paper uses the finite difference software FLAC^3D to build a parallel double-hole tunnel model based on the shallow buried excavation tunnel project of Liucun Road reclaimed water and sewage pipelines in Beijing.The numerical simulation of the parallel double-hole tunnel construction process using the upper step and the reserved core soil method is carried out..Based on the results of numerical simulation,the road surface settlement clouds and settlement curves after the completion of the construction of the first tunnel and the completion of the tunnel construction are obtained,and the numerical simulation results are compared with the theoretical analysis values and monitored measurement values to obtain a parallel two-hole tunnel in the vehicle.The effect of load on the road surface settlement.On the basis of simulating the construction conditions,further numerical simulations were carried out on factors such as full-section excavation construction,different upper step lengths,different cyclic excavation lengths during tunnel construction,different vehicle speeds,and different buried depths of the tunnel.Impact on the project.On this basis,further numerical simulations were carried out on factors such as full-face excavation method construction,different upper step lengths,different cyclic excavation lengths during tunnel construction,different vehicle speeds,and different buried depths of tunnels,and various factors were analyzed for this project.Finally,it is concluded that the law of settlement curve is not affected by the construction method,depth of tunnel,vehicle load and construction parameters,and all of them conform to the normal distribution law.The effect of full-face excavation method on road surface settlement is not significantly different from the step method,but it seriously affects the stability of tunnel face and surrounding rock;when the construction quality and construction efficiency are ensured,the length of the step on the tunnel can be reasonably selected between 4.5⁶.75m;the length of each cycle of tunnel excavation in this project should be taken as 0.5m,which is not appropriate if the tunnel is too large,or the surrounding rock of the tunnel is easily damaged or even landslides.During the construction of the raw water and sewer pipeline tunnels,the speed limit near the construction section of the South Third Ring Road is recommended to be 40km/h to ensure construction safety and driving safety;the greater the tunnel depth the impact of the construction process on the settlement and deformation of the road surface is smaller.When the depth of burial depth is changed,the parameters of the formation will also change.It is recommended to avoid the gravel and round gravel layers when grouting the tunnel.The analysis results in this paper provide reference and consult for related projects in similar regions,and provide some prospects for related research in the future.