Study On Bearing Mechanism And Deformation Characteristics Of Novel Geosynthetic-reinforced And Pile-supported Low Embankment Of High Speed Railway

The novel geosynthetic-reinforced and pile-supported low embankment(named novel GRPS low embankment),combining the advantages of the conventional technique of GRPS embankment(named CT embankment)and the fixed geosynthetic technique of GRPS embankment(named FGT embankment),has good application prospect in the treatment of poor ground of high speed railway.The force and deformation behavior of the structure in which high strength geotechnical grille is fixed on the pile cap under dynamic load is complicated,and there is currently a lack of the systematic theoretical basis for design of this structure.Therefore,through the means of numerical calculation and theoretical analysis,the load transfer mechanism and deformation law are studied.The deformation characteristics and reinforcement mechanism of pile-supported embankment are summarized and analyzed.Due to the contradiction between the requirement of high-speed railway low embankment is to strictly controls the settlement and uneven settlement and the existing deficiency of GRPS embankment,novel GRPS low embankment is put forward for the low embankment of high speed railway.By summarizing the theoretical research on the load transfer mechanism of novel GRPS low embankment,the paper puts forward the semi-elliptic soil arching model of the same eccentricity and the evolution process.And through the analyze of the forced state of novel GRPS low embankment,the calculation method of the soil arching effect and tensioned membrane effect is given.The theoretical calculation method for the load transfer of novel GRPS low embankment is obtained.Considering fluid-solid coupling,a 3d numerical model is established.by the finite element analysis software FLAC3 D.The vertical settlement and lateral deformation of novel GRPS low embankment are studied by comparing it with CT embankment and FGT embankment.Under the same load condition,embankment settlement and lateral displacement of novel GRPS low embankment are the smallest.The largest vertical settlement is only 84.8% of CT embankment and 94.5% of FGT embankment.Its maximum lateral displacement is 90% of CT embankment and 99% of FGT embankment.Calculation results show that novel GRPS low embankment adds a layer of grille,which can further improve the fixed geosynthetic technique performance,reduce the embankment settlement and uneven settlement,restrain the lateral displacement of embankment and improve the integrity of reinforced embankment compared with the fixed geosynthetic technique.This paper summarizes the characteristics of geogrid and its strengthening mechanism,and four stages of work characteristics in grid drawing test.The construction technology of geogrid roadbed reinforcement is summarized,and the key processes such as geosynthetic pretensioning and the fixed geosynthetic technique are described.Some quality control problems of the reinforcement process are analyzed,and the reinforcement effect of geogrid is ensured.