Research On Construction Technology Of Oblique Excavation Under Inclined Crossing Under Urban Overpass

With the development of society,the construction environment is becoming more and more complex,the construction difficulty is increasing,and the construction requirements are becoming more and more strict.In the face of challenges,optimize traditional construction methods,speed up construction progress,improve construction quality,and maximize economic benefits while meeting engineering requirements.This paper relies on the Zhengzhou Citizen Public Cultural Service District Comprehensive Pipe Gallery Project,using theoretical analysis combined with the MIDAS-GTS numerical simulation method to optimize the construction scheme of the PBA method for the side-by-side viaduct,and compare the calculation results with the on-site monitoring data.Analyze and study the influence of construction process on bridge piles,vaults and ground surface,and summarize the deformation laws and mechanical properties.The main research contents and conclusions are as follows:1.When the whole underground excavation is applied to the pipe gallery adjacent to the bridge pile,the displacement of the bridge pile is too large to meet the engineering requirements.After the optimization scheme,the receiving wells are cut-off in the adjacent piles.The numerical simulation and on-site monitoring results are all within the control standard.Under this condition,the scheme can greatly reduce the deformation of adjacent existing bridge piles.2.Through the MIDAS-GTS modeling calculation,the feasibility of one-time arching is proved,and the displacement and deformation laws of the surface and the vault under different arching steps and footage are compared and analyzed.The direction of the arching behind the direction of the working well.Considering the construction efficiency and deformation requirements,the arch is applied with a 6m footage.The stress value of the vault is mainly distributed between 0.14-0.35 Mpa.In the process of buckle arching,the initial lining change is broken,resulting in a steep increase in the stress of the vault.The stress increases by about 7%-10%,and the stress at the arch foot is large.3.The maximum horizontal displacement of the bridge pile is 5.31 mm.The horizontal displacement along the direction of the pile increases with decreasing depth.It is zero at around 30 m and then increases backward.The maximum vertical displacement of the bridge pile is 5.46 mm,and the deformation is characterized by the small pile end of the pile top,which decreases with the direction of the pile body.The axial force of the bridge pile decreases with the increase of the buried depth of the pile.During the construction process,the axial force of the pile is reduced,resulting in an increase in the axial force of the pile.Mainly manifested in the receiving well,the pilot hole excavation and the stage of the arching,so the design and construction will strengthen the corresponding stage.4.The surface subsidence increases with the progress of the construction,and the whole is groove-shaped,which is symmetrically distributed in the middle line of the pipe gallery.The maximum surface settlement around the bridge pile is 10.5mm,and the maximum settlement value of the surface in the dark excavation section is 34.8mm.Compared with the original scheme,the maximum surface settlement is reduced by 7.0%.5.The application of lightweight concrete greatly reduces the structural weight and improves the safety of the arch.It also saves the use of materials and reduces the construction cost,and has good economic benefits.The erection of steel sheds not only has the advantages of reducing environmental pollution,reducing construction noise,beautifying the city and other green environmental protection,but also can guarantee the construction of the project around the clock,avoiding the impact of weather on the construction,speeding up the construction progress,and promoting it in similar projects.