Technical Discussion On Performance-based Seismic Design Of Retaining Structure Of Railway Subgrade

As an important structure to ensure the smooth passage of the railway line,the railway retaining structure needs to play its role in retaining the soil body,maintaining the stability of the roadbed,protecting the line and adjacent buildings during the earthquake.Therefore,it is necessary to analyze the earthquake resistance of the railway retaining structure,including the seismic earth pressure of the retaining structure from the soil behind the wall,horizontal seismic force of the retaining structure used for the calculation of anti-slip and anti-collapse,and the performance of the retaining structure under the action of earthquake.In order to discuss these issues,the thesis mainly did the following work:(1)The pseudo-static calculation method for seismic earth pressure of retaining structure is summarized,including the derivation of the M-O method formula,the solving process of horizontal layer analysis method,etc.For the current domestic seismic design codes,the seismic response spectrum and equivalent base shear method are used,and different coefficients are used when calculating the horizontal seismic force,reducing the gap of the seismic response between the elastoplastic structure and the elastic structure,and these coefficients include considerations of different structural self-vibration period,damping ratio,seismic intensity,site category,design earthquake grouping and other factors.It mainly includes structure influence coefficient and earthquake influence coefficient,among which the structural influence coefficient is mainly influenced by the ductility and overstrength of the structure.At the same time,comparing the different expressions of the values of the comprehensive impact coefficients in the domestic seismic design codes,and comparing the horizontal seismic forces of elastoplastic structures under fortified earthquakes and elastic structures under frequent earthquakes,the results are found to be very close.(2)The finite element method is used to model and analyze the specific railway retaining structure.The results show that the infinite element boundary can handle seismic wave transmission from the base,and acceleration,deformation of the retaining structure,overall displacement,seismic earth pressure and static earth pressures are all reasonable,verifying the reliability of model building and analysis methods.(3)The performance levels and performance objectives of performance-based seismic design in domestic and foreign codes are compared and organized into tables.Regarding Pushover analysis,it introduces in detail how to use the capacity spectrum method and the equivalent linear method to determine the performance point.The concrete cantilever retaining structure is modeled and analyzed,and the modeling ideas and simplified schemes are introduced in detail.The performance of the retaining structure under the action of earthquakes of different levels is calculated,and a preliminary design is made for the performance level and performance objectives of the cantilever retaining structure.