Study On The Structure Optimization Of Heavy Haul Railway Subgrade

Heavy haul railway transportation is an inevitable trend in the development of railway freight transportation.Increasing the train axle load is an effective means to improve the transportation capacity.However,increasing the axle load and traffic volume will lead to serious strength and fatigue problems,which will lead to the occurrence and development of roadbed disease.The Chinese Heavy-haul Railway Design Specification has explicitly defines the subgrade of the structure type,as well as the thickness of the structure layer,packing and compaction standards.However,there are still many problems in practical application.For example,there is a problem of simplification in the type of subgrade structure that cannot be adapted to the geographical differences in our country.Therefore,it is necessary to analyze the use of the existing type of heavy haul railway subgrade and put forward a reasonable structure optimization plan of subgrade to promote the further development of heavy haul railway.In this paper,theoretical analysis,field measurement and numerical simulation are used to optimize the structure of subgrade.The main research contents and conclusions are as follows:(1)Monitoring the dynamic response of the Shuohuang heavy haul railway subgrade.The dynamic stress and dynamic deformation of the subgrade increases with the increase of the axle load.The most affected area is the surface of subgrade.Therefore,it can be determined that the subgrade is the main research object in the research process of the heavy haul railway.(2)Change the elastic modulus of each structural layer and simulate it.The conclusion is that,the elastic modulus of the surface of subgrade increases,the dynamic stress on the surface of the surface of subgrade is significantly increased,and the dynamic stress of the bottom of subgrade and the bedrock is slightly reduced.The elastic modulus of the bottom of subgrade increases,the dynamic stress on the surface of subgrade increases slightly,the dynamic stress of the bottom of subgrade increases significantly,and the dynamic stress of the roadbed decreases slightly.The elastic modulus of bedrock increases,the dynamic stress of surface of subgrade and the bottom of subgrade increases slightly,and the dynamic stress of bedrock increases significantly.(3)Damage analysis can be obtained,when the design axle weight is 30 t,and the standards of other structural components are designed in accordance with the requirements of China's current technical specifications.It is concluded that the best stiffness matching of the surface of subgrade,the bottom of subgrade and the bedrock is about 540 MPa/ m,200 MPa/m and 80 MPa/m.(4)Compared with the traditional type,the combination of the increase thickness of 15 cm asphalt layer is compared with the traditional one.The dynamic stress on the surface of subgrade reduced by about one third,and the service life is expected to increase multiply.The results show that the quality of subgrade is improved obviously,which can prevent the subgrade diseases.