Study On Characters Of Deformation And Load Bearing Properties For The Pile-board Subgrade Of Lan-xin Railway In Permafrost Region

Pile-board subgrade is a new type form of ballastless track in high-speed railway, the rigidity bearing plate in the structure having well ride performance could provide enough stability for the upper part of the track structure. This paper was depended on the pile-board subgrade of Lan-Xin railway in permafrost region, to research the pile-board subgrade with independent pile in permafrost environment.Utilizing the access to a large number of literatures, learn the popular research methods and tools at present in pile-board subgrade fields, and analyze the existing theoretical achievements of the p ile-board subgrade at the same time, then using numerical simulation test methods, combined with engineering project to establish the three-dimensional numerical computational model about the pile-board subgrade. By add a vertical load, then analysis the deformation characteristics of pile-board subgrade and the mechanical properties of the pile foundation and the bearing plate. After the subgrade processed with pile-board structure, the total settlement deformation, the flexural deformation of bearing plate, and other could meet existing the relevant specification requires of high-speed railway subgrade.By add the effect of vertical load, change the elastic modulus of concrete piles, the piles’ length, the pile spacing at the d irection of longitudinally and other influence factors, then detailed study the deformation characteristics and mechanical characteristics of pile-board structure. Through the simulation analysis, the elastic modulus of concrete piles and longitudinal pile spacing are the main influence witch is greatly affected the deformation of subgrade. When the elasticity modulus of piles is relatively small, increasing the elastic modulus can effectively control the total deformation of the subgrade;When the elasticity modulus of piles is very large, increasing the elasticity modulus is not conducive to controlling total settlement of subgrade. Aimed at the particularity of high-speed train’s dynamic load, establish the three-dimensional numerical computational model about the pile-board subgrade for dynamic analysis. Add the dynamic loads to pile-board subgrade, when the high-speed train’s speeds are 200km/h, 250km/h, 300km/h and 350km/h, and study the dynamic characteristics of the foundation soil, pile foundation and bearing plate in the pile-board subgrade. The dynamic response of the pile is mainly in the upp er part of the pile body. And the faster the trains’ speed, the more remarkable of the dynamic response.The foundation soil in DK366+021~DK366+089.44 of Lan-Xin railway could belong to patchy permafrost. It is the first time to using pile-board structure to deal with the railway subgrade in permafrost region, where was transition section between bridge and tunnel. By finite-element simulations, it is a very meaningful thing to analysis and study the deformation and structural internal force characteristics for pile-board subgrade under the action of temperature load in frozen soil environment. In view of the finite element software ANSYS have enough reliability and authority on simulation analysis of temperature field. And this paper could use ANSYS to establish numerical computational model about pile-board subgrade for temperature load. Analysis the deformation characteristics and structural internal force regular, when the temperature reduction 30℃. The structure of t piled slab could appear the internal force of the struc ture under the temperature load; In the horizontal, the temperature stress in the bearing plate is symmetrical, and the direction is the opposited.