Improving Methods and Mechanism of Bending Fatigue Performance of Ballastless Track Concrete
In order to improve the fatigue life of ballastless track concrete within the designed service life,in this paper,ballastless track concrete bearing the high-frequency fatigue load of trains was studied,and the bending fatigue life was statistically analyzed by Weibull distribution function.The effects and mechanism of strength grade,polymer-modified technology,and alkali resistant glass fiber bridging on the fatigue resistance of concrete were investigated,by means of image analysis and pore structure analysis.The results show that compared with the benchmark C60 concrete,the fatigue life of C80 concrete is increased by 12.7％～29.7％,due to a 6.9％decrease in concrete porosity and a 40.3％increase in energy absorption capacity before fatigue failure.However,the peak strain is reduced by 7％,with the proportion of dissipated energy being reduced to 9％,indicating that the increase in concrete brittleness affects the further improvement of its fatigue performance.The fatigue life of polymer-modified concrete is increased by 21.0％～57.5％,with section cracks being not completely connected during fatigue failure,with the width of only 0.7 mm.The reason is that polymers can fill the pores of concrete,improve the toughness of the grout and the bonding performance between grout and aggregate,so that the deformation and energy absorption capacity of polymer modified concrete are increased by 27.0％and 74.2％.The fatigue life of glass fiber reinforced concrete is increased by 18.6％～41.1％,and the fa-tigue failure mode proves that the bridging and stress dispersion effects of glass fiber are the main reason for the improve-ment of its fatigue life.
万方数据
维普
