Mechanics And Maintenance Standards Of Connection Damage For CrtsⅢ Slab Track

CRTS III slab track is the development of independent innovation of China’s high-speed railway ballastless track structure, self-compacting concrete layer as the key structure layer, its performance is connected with the track slab will affect the application effect of the orbital.Self-compacting concrete layer in the service period will inevitably produce a variety of diseases formed from connection damage, track slab from under the joint effects of track structure stress is not clear, lack of layer alienation joint repair standard. In this paper, CRTS III slab track layer from joint damage was studied, mainly includes the following research contents and conclusions:(1) Based on the field investigation, the CRTS III slab track damage characteristics are summarized, its damage mainly prestressed steel bar rupture sprang, self-compacting concrete layer and the support laye/base slab or slab alienation joint grout, rail station abutment crack. From the concrete layer crack structure theory and the new to old concrete interface is weak, primarily expatiates from seam formation.Research shows that, CRTS III slab track gap formation contains its own self-compacting concrete materials, construction process, the external environment and train load, is the result of joint action of multiple adverse factors.(2) Through the reasonable simplified mechanics, a CRTSIII slab track static analysis model, using the finite element method, using the element birth and death and contact technology, effectively simulate the track slab and self compacting concrete layer interface between gap between layers, considering the train load and temperature gradient alone or together, aiming at different position and length layer alienation joint influence on track structure stress research.Results of the analysis show that, away from the seam along the longitudinal development to the former group2-3fastener distance track of each member of the maximum stress increased obviously, and the maximum stress is maintained at a high value. The negative temperature gradient effect, appear in gap will make the track slab corner at a high longitudinal tensile stress state, may lead to the emergence of new angle of slab damage conditions; edge appears from the seam will make self-compacting concrete layer from the corner at a high longitudinal tensile stress state, may cause further damage of self-compacting concrete layer from the joint development, aggravated the damage conditions. No matter what kind of load, away from the seam area as long as the door bar, will significantly increase the axial door type reinforcement tensile, compressive stress, although not lead to sudden failure of door type steel, but in the repeated loading, will it be possible to make the door type steel fatigue failure occurred, so that the damage condition aggravation.(3) Binding force on the track structure analysis results, the joints of reinforced concrete around the door to analyze stress state.The results show that the interaction, the negative temperature gradient or negative temperature gradient and under train load, away from the seam subjected to longitudinal tensile stress decreased significantly at the track slab and concrete, self-compacting concrete subjected to longitudinal tensile stress increased significantly, may exceed its allowable tensile stress, door type reinforcement is higher under axial tension stress. Near the end, board the first gate bars in the gap may occur under the door type rib bad self-compacting concrete situation, and under temperature cycling under repetitive, self-compacting concrete layer will accelerate development, door type steel fatigue damage; positive temperature gradient or positive temperature gradient and train loads next, from seam under transverse tensile stress decreased at the track slab and concrete, self-compacting concrete subjected to transverse tensile stress increased, door type reinforcement under large axial tensile stress state, under temperature cycling under repetitive, self-compacting concrete may accelerate the development of layer, door type steel fatigue damage.(4) The discriminant index through the analysis of repair, on this basis, analysis of track structure based on the combination of static, from joint damage characteristics, starting from the fatigue and durability point of view, put forward the CRTSⅢ slab track layer offset joint repair level and criterion, for out of joint damage to the proposed repair method.Recommended layer alienation suture repair level is divided into three levels, the longitudinal length, horizontal length and gap position (slab edge, in the slab and under the rail) three parameters define the repair criterion.