Study On Mechanical Performance Of Post-installed Anchorage System Between Ballastless Track

Ballastless track has become the main track structure form of high-speed railway due to its high smoothness,high stability and less maintenance.As the track service time increases,some diseases which are influenced by external factors and train loads inevitably appear in the track structure,such as the separation between the track slab and the CA mortar layer,the arch of track slab,and the wide joint damage,etc.Postinstalled anchorage technique is one of the common methods to prevent and renovate these diseases,which has a good effect.At present,there are still some deficiencies in the studies of the mechanical performance of the anchorage anchors for ballastless track,which cannot provide sufficient theoretical support for the application of the postinstalled anchorage technology in ballastless tracks.Therefore,in this paper,two equivalent mechanical models of post-installed anchorage system were established by analyzing the mechanical properties of the planted anchorage for ballastless track in a small scale model at a microscopic view,and then,they were applied to the mechanical analysis of post-installed anchorage system in ballastless track under group anchor and research on post-installed anchoring scheme for track slab.The main research contents are as follows:(1)The pullout resistance performance of post-installed anchorage system in ballastless track at a mesoscopic angle is studied.After analyzing the uplift-restricted mechanism of post-installed anchorage system,a refined model of post-installed anchorage system is established based on cohesion.Through the analysis results of the distribution characteristics,development rules of stress and strain of post-installed anchorage system and its failure process under load,the vertical load-slip curve of postinstalled anchorage is obtained,so that the nonlinear spring equivalent mechanical model of post-installed anchorage system effected by pullout resistance performance can be established.(2)The shear resistance performance of post-installed anchorage system in ballastless track at a mesoscopic angle.After analyzing the uplift-restricted mechanism of post-installed anchorage system,a refined model of post-installed anchorage system is established based on cohesion.Through the analysis results of the distribution characteristics,development rules of stress and strain of post-installed anchorage system and its failure process under load,the horizontal load-slip curve of post-installed anchorage is obtained,so that the nonlinear spring equivalent mechanical model of post-installed anchorage system effected by pulling resistance performance can be established.(3)The stress of post-installed anchorage system in ballastless track under group anchor is analyzed by using the equivalent models mentioned above.According to different post-installed anchorage conditions,the distribution of uplift-restricted force and slip-restricted force of post-installed anchorage system can be analyzed.The result indicates that the distance between the first row of anchor and the ends of the track plates should be set between 150-600 mm,and the lateral spacing of anchors should be set between 200-1100 mm when multiple rows of anchors are arranged longitudinally along the track plate.(4)The post-installed anchorage schemes of CRTS II slab ballastless track are studied by using the equivalent models mentioned above.The post-installed anchorage schemes to regulate the arch of track slab of CRTS II slab ballastless track are designed,after calculating them though simulation by combined with the equivalent mechanical models,a reasonable rectification scheme can be put forward.