Study On Performance Of Box-type Roadbed Structur Of High-speed Railway

Box-type roadbed of high-speed railway is a new type of roadbed,which is made of reinforced concrete and does not require roadbed filling.It has the advantages of light weight,high strength,good integrity,and less land occupation.It has a great application prospect in plain areas and areas lacking in filling of our country.As a new type of roadbed structure,boxtype roadbed is obviously different from traditional roadbed or bridge,and there is no practical application in engineering.There are problems such as immature design theory and unclear structural performance and so on.This paper takes the box-type roadbed as the research object,using theoretical analysis,dynamic and static numerical calculation methods to study its statics characteristics and dynamic response.This paper summarized the structural type and engineering design of box-type roadbed,analyzed the internal force characteristics and stress transfer path of box-type structure from the perspective of structural mechanics,put forward the simplified stress plane of box-type structure,and analyzed the stress and deformation mechanism of double-layer reinforced cushion and pile foundation,determined the calculation method of bearing capacity and settlement of composite foundation,and carries out the calculation.In this paper,the static calculation model of box-type roadbed was established,the internal force distribution and deformation laws of the box-type structure under different load conditions were studied,and the settlement and deformation characteristics under different foundation treatment conditions were compared.The results show that the internal force distribution and deformation of the box-type roadbed have high symmetry,the top and bottom plates are mainly subjected to bending and shear forces,and the side walls are mainly subjected to eccentric compression;composite foundation can significantly reduce the settlement of the foundation and lateral displacement.Compared with the analytical method,the numerical calculation results can reflect the settlement deformation mechanism of the composite foundation,which is more in line with the actual situation.The dynamic model of vehicle-track-box-type roadbed was established by using ABAQUS finite element software,and the sensitivity analysis of box-type roadbed parameters was carried out.The modal analysis of the box-type roadbed structure shows that the natural frequency of the box-type roadbed structure is much higher than the vehicle loading frequency and will not resonate with it.In this paper,the dynamic performance evaluation index of box-type roadbed is determined.After,comparing the calculation results of parameter sensitivity analysis with it,the results show that all dynamic parameters meet the requirements of evaluation index.In order to study the engineering characteristics of box-type roadbed more accurately and comprehensively,two groups of monitoring schemes were designed: excitation test and longterm monitoring test,and the evaluation method of box-type roadbed service status was developed,which laid the foundation for the subsequent field test.