Study On Stress And Construction Process Of Underground Rectangular Frame Bridge Under High Water Level Geological Conditions

With China’s reform and development,the continuous advancement of my country’s urbanization level,the urban traffic pressure is gradually increasing,and the original road level crossing system is no longer suitable for the needs of modern cities.In order to solve the problem of road crossing under the condition of limited street space,one of the main methods is to build an underpass frame bridge and change the level crossing into a three-dimensional crossing.At present,changing road and railway level crossings into interchanges has become an urgent and arduous task to improve urban traffic conditions and ensure traffic safety.The upper-span and lower-crossing highway overpass structures are both the main forms of urban level-replacement traffic crossings,but the lower-span highway overpass structure and the upper-span highway overpass have great advantages in terms of economy,urban planning land area,construction form,and aesthetics.The structural form of the underpass highway overpass is mainly a frame bridge,and its main structure is a box frame.The main advantages of the structural design are good integrity,high rigidity,and strong resistance to deformation.It is suitable for places with low foundation bearing capacity and large uneven settlement.With the improvement of land utilization,the use and construction of underground bridges has become a hot topic in the development of current transportation construction.It can be better used in practical engineering.Therefore,the stress of frame bridges under different geological conditions has been paid more and more attention by designers and scholars,and corresponding research has been carried out,but the stress analysis and construction process of underground rectangular frame bridges under high water level geological conditions less.Relying on the Yellow River Crown World Garden Project,this paper studies the stress analysis and construction process of the underground rectangular frame bridge under high water level geological conditions.The specific work of this paper is as follows:(1)Aiming at the rectangular frame of the high water level underground bridge structure of the Yellow River Guanshi Garden Project,this paper introduces the relevant concepts of the underground rectangular frame structure,and summarizes the geotechnical engineering investigation data of the project;expounded,and summarized and introduced the main indexes of each layer of foundation soil;finally,introduced the construction design drawings of the project.(2)According to the existing data,the finite element model of the underground rectangular frame bridge is established.Then,the finite element model was analyzed under five load cases of self-weight,earth pressure,temperature,vehicle load and the most unfavorable load combination,and the distribution of shear force,deformation and bending moment of the rectangular frame under each load case was calculated.Then,the seismic analysis of the rectangular frame is carried out,and the time history analysis diagram of the structure under the seismic wave is obtained;finally,the overall stability of the structure is analyzed,and the overall stability of the rectangular frame structure is obtained to meet the requirements.(3)The finite element software Midas Civil is used to analyze each stage of the construction process,and the bending moment,shear force and deformation of each stage are obtained through calculation,and it is found that the internal force and deformation of each construction stage meet the requirements;According to the analysis,the structural stability of each construction stage meets the requirements;finally,the matters needing attention in the construction process are summarized.(4)According to the bridge design drawings and the measurement and experimental data of each construction stage in the construction process,the key points and difficulties in the bridge construction under high water level geological conditions are analyzed,the relevant precautions are put forward,and the main body of the underground rectangular frame bridge under high water level geological conditions is compiled.Construction technology,construction technology for dewatering and drainage,construction technology for deep foundation pit excavation,and construction technology for side slope bolting and shotcrete support,etc.,have formulated safety and quality assurance measures,foundation pit inspection and monitoring measures,and on-site inspections,etc.Effective measures,the formation of instructive construction technology and construction guarantee measures,etc.provide reference for the construction of other projects.