G And Analysis On Beam Creep Deformation And Pile Foundation Settlement Of High-speed Railway Bridges

Abstract:With the wide-spread application of viaduct bridge in high-speed railways, elastic deformation under live load and long-term deformation under dead load of bridge structure are expected to impose negative effect on load bearing capacity, ride comfort and safety. Due to limited height of ballastless track’s fasteners, it is necessary to strictly contain creep of beams and settlement of pile foundations. Accurate monitoring of creep deformation during post-construction period is the precondition to ensure safety of high-speed railway’s operation.Based on "Research on Automatically Remote and Integrated Monitoring System of Deformation of High-speed Railway’s Underline Engineering in Perilous Mountainous Region (Contract No:2010G018-E-3)", Main work and achievements of this thesis are as follows:(1) Huge amount of foreign and domestic researches on creep of high-speed railway bridges were collected. Principle and nature of creep were analyzed by exploring foreign and domestic calculating methods of creep deformation. Computing methods of pile foundation settlement and current routine ways of monitoring bridges were summarized. Special attention was paid to sum up experience about application of hydrostatic leveling system (HLS) at home and abroad.(2) In light of Shangyu Bridge and Cao’er River Bridge in Hangzhou-Ningbo Passenger Dedicated Line(PDL), HLS test plan was designed for the test worksites. By using HLS to automatically monitor creep deformation and pile foundation settlement of high-speed railway bridges, time-dependent vertical displacement law of beams and pile foundations was gained since the erection of beams. Position-dependent relative vertical displacement curve of beams and pile foundations of typical point-in-time were drawn. Creep deformation and pile foundation settlement of two bridges during post-construction period was compared. Standard limitation was compared with measured value which, as a result, matches the standard. The application of HLS was analyzed so as to offer advice for related construction.(3) A model of simply-supported box girders of the high-speed railway was built by using Midas/Civil software. The creep trend of simply-supported box girders of high-speed railway was explored by this model through simulating different stages of construction according to actual working situation.3standard models were adopted to calculate the creep degree of mid-span section of beams and the result was compared with measured value obtained from HLS so as to work out a reasonable computing model, through which long-term creep deformation of bridges were predicted.(4) ABAQUS, a kind of finite element software, was used to build models of pile foundation of the typical bridge in the test worksite. What’s more, based on actual working situation, different stages of construction were marked off and the settlement of pile foundation was calculated according to passage of time. By comparing result from calculating with measured value, long-term settlement of pile foundation were predicted.62figures,20tables and102bibliographies were...