Numerical Analysis And Application Of Oblique Intersection Jacking Of Shallow Overlying Soil Underpass Bridge At Large Intersection Angles

With the rapid development of national highway traffic and the continuous improvement of highway network system,the intersection between new roads and existing roads is becoming more and more frequent.Because the jacking construction method of underpass bridge has the advantages of no impact on the existing road and fast construction speed,it has become an advantageous construction method for underpass the existing road.Although some research on jacking construction technology of underpass bridge has been carried out at present,the research on jacking construction of underpass bridge with large intersection Angle and shallow overlying soil is relatively few.The main manifestations are as follows:there are few studies on the calculation method of maximum jacking force of oblique jacking of underpass bridge;There are few researches on the stress and deformation laws of structure and soil in the jacking process of shallow overlying roadway bridge with large intersection Angle.Based on the jacking project of NK1+100.2 underpass bridge of Pingjiangnan Interchange of Pingyi Expressway in Hunan Province,this paper mainly conducts the following studies:(1)The calculation formula of maximum jacking force of underpass bridge is derived;A program for calculating the maximum jacking force of underpass bridge based on BIM technology is developed,which can calculate the maximum jacking force value of orthogonal or oblique intersection.On this basis,the results of calculating the maximum jacking force of NK1+100.2 underpass bridge by hand and by program are compared and analyzed.(2)Midas-GTSNX finite element software is used to establish the finite element model of jacking construction of shallow overlying road bridge with large intersection Angle.According to different soil thickness,jacking process and jacking force value,28 working conditions were analyzed by finite element method.(3)By analyzing the numerical results of underpass bridge jacking under different working conditions,the structural deformation and stress of underpass bridge in the process of oblique jacking construction and the change rules of soil displacement under different jacking stages are studied,providing theoretical basis for the safety of underpass bridge jacking construction.(4)Based on the above research results,taking NK 1+100.2 underpass bridge as an example,the maximum jacking force value is calculated,which provides guidance for the layout of jacking jacks;At the same time,the construction method based on steel shield and the deviation correction measures in the jacking construction process of underpass bridge are studied.Through the research on the key construction technology of jacking of shallow overlying soil oblique underpass bridge with large intersection Angle,it is expected to provide reference for the construction of similar projects.