Investigation On Influence Of Widening Construction Of High-speed Railway GRPS Embankment And Causes Analysis With Treatment Of Abnormal Deformation

In geogrid-reinforced and pile-supported embankment structure,the foundation soil and pile bear the load from embankment soil together which ensure the performance of bearing capacity of soil between piles.This kind of structure effectively limits post-construction settlement and differential settlement,short the construction period and save costs of projects.These features make it strictly fit the requirement of high-speed railway ballastless track line which are build in deep soil conditions.The widening construction of embankment causes the increase of exiting embankment and may affect the normal use of the line if the deformation developed seriously.The GRPS embankment and railway subgrade widening construction will have broad application prospects.The research on the influence of the widening construction and the investigation of causes analysis and treatment of abnormal deformation have a more profound theoretical and practical significance.In this papper,the widening construction of GPRS embankment in Chaohu East Station is studied.And the main research contents and results are included as follow:1.3D analysis model of GRPS embankment was built using Plaxis finite element analysis software.Embedded pile model was choosen with matching pile cap model and geogrid model to simulate the load transfer mechanism of GRPS embankment.The same construction sequence and period was adopted to simulate deformation and stress characteristics.The accuracy of the modeling method was verified by the comparision between calculated results and measured results in literature.2.The GRPS embankment was studied with verified model to state the deformation and stress characteristics of embankment filling stage.The process of soil arching and the interaction among piles,soils and geogrid were discussed.The overall tension of geogrid intends small which turns into non-controlling factors.The height of soil arching reaches about 1.7 with pile space 2.2m.The embankment soil load transfered to the piles are higher than 90%in this GRPS embankment with 10 pile-soil stress ratio which means the design was partial consevative.3.Widening construction and slope-cut construction were simulated to indicate the influence of the construction employing increment describing method.The influence of slope-cut construct is insignificant and the symmetry is unaffected considering the asymmetry of construction sequence.The geogrid is less affected by fill but the load transferred to piles increseas rapidly into close level between to shoulders.As for the pile tops,the deformation doesn't change but the moment reduce.4.Three potential conditions which may cause the abnormal deformation of Chaohu East Station were Simulated to show the deformation development law of each condition.When the soil of bearing layer distributed uneven,the deformation mode of both directions matched the measured.And it is pointed that the differential settlement caused by the pile bearing mechanism difference between left side and right side of the embankment leading to abnormal lateral deformation.5.Two different treatment measures were put forward after the abnormal deformation mechanism was clarified.The treatment effect of each measure was tested combined with simulation and analysis.The effect of treatment that employs tip resistance mechanism friction behaves better than the treatment which employs shaft resistance.As for deformation control,the pile foudation of GRPS embankment should reach the bearing layer.