Study On The Assessment Theory And Measures Of Subgrade Quality Of Datong-Qinhuangdao Heavy Load Railway

High-speed line and heavy haul railway are two major trends in the development of world railway, and heavy haul freight transport has become an important symbol of modern railway freight transport. In order to solve the long-standing contradiction between transport capacity and traffic volume of the railway, the axle load and train speed increased, that the deformation of roadbed and dynamic interaction of train-track system are more aggravated. Especially after a wide range of speed, the geometry bit of track of existing railway difficult to maintain long-term, the growing number of disease appears on subgrade, in particular, more extensive and severe in transition section, is a major case of traffic accidents. Therefore, to study that, if the subgrade quality of existing railway can meet the requirement of driving safety, have a very important practical significance.This paper relying on the research project of Datong-Qinhuangdao heavy haul railway, select a typical cross-section of bridge test, using filed test, theoretical analysis and numerical calculation methods, etc. to study the deformation of subgrade in bridge-subgrade transition section of Datong-Qinhuangdao heavy haul railway, and the subgrade quality inspection and strengthening measures are also studied. The main research work of this paper as follows.Through the static test in filed and laboratory test on subgrade, the Foundation Coefficient K30, Deformation Modulus Ev1 and Ev2, Density and Water Content were tested; a detailed research is done on the results of subgrade quality inspection of the transition section combined with field test data. The testing results indicate that, the closer the distance to abutment the bearing capacity of the soil lower, the transition section is the focus of strengthen; One of K30 and Ev2 can be used as a mechanical index of compaction quality control of roadbed, and using the physical index to supplement control of subgrade compaction.Through the dynamic characteristics test of bridge-subgrade transition section, the subgrade dynamic stress and dynamic changes of the displacement were analyzed. The test result indicate that, along the depth direction, the dynamic stress decay rapidly; Longitudinal along the line, the dynamic stress tends to decrease with the distance of test points to dot pitch increased; Train speed, axle load and track structure all have affect on the dynamic stress of subgrade. The deformation law of subgrade under static load of train is analyzed by using ANSYS finite element software, analyzed the impact of changes of the parameters on the deformation of embankment. The research result indicate that, the maximum deformation distributed in the center of static load on both sides of horizontal subgrade; The deformation modulus of surface layer of subgrade, roadbed of, basement and foundation all have influence on the subgrade settlement.The strengthen scope of bridge-subgrade transition section are studied based on the field test result, dynamic characteristics test results and numerical analysis result, the results indicate that transition section and surface layer of subgrade is the focus of strengthen, the strengthening measures in bridge-subgrade transition section are discussed at the end.