| Some sections of longitudinal slab ballastless track of high-speed railway have prominent arch diseases in summer high temperature season,which seriously affect track smoothness and even endanger driving safety.The road bureau department mainly adopts the way of pin anchoring for prevention and treatment.The stress mechanism of track with pin anchorage limit is different from that of traditional longitudinal slab ballastless track.Further research is needed on the bearing and transmitting characteristics of pins,static and dynamic performance of structural system and the influence law of anchorage pin damage of longitudinal slab ballastless track.In this paper,the structural model of anchoring pin and the static and dynamic model of longitudinal track-pin system are constructed,and the action mechanism of temperature-varying load and braking load on anchoring pin structure is revealed The influence of load parameters and anchorage parameters on the stress and deformation of longitudinal connection system is analyzed The influence mechanism of different speed,interlayer state and pin anchoring parameters on the dynamic behavior of track structure is analyzed The dynamic response characteristics of pin and the influence law of pin damage on the stress deformation and dynamic response of longitudinal slab ballastless track are revealed.The main research results are as follows:(1)The longitudinal behavior and structural bearing characteristics of longitudinal connection-pin system under static loadUnder temperature-varying load,the main body of pin bearing presents the distribution law of large in the middle and small at both ends.The pins transfer load mainly through the bonding force between the middle area and concrete,and the area gradually increases with the increase of temperature.The limit capacity of pins is mainly limited by the strength of surrounding concrete.Under the action of braking force,the stress distribution of pins presents M-shaped characteristics.Pins mainly transfer loads through the bonding force between the middle area and concrete.Considering the complete defect of the joint,cracking will occur between the pin-CA mortar/base plate interface under the action of braking force.It is suggested to increase the inspection of wide and narrow joints to ensure that there is no obvious defect in the joints.(2)Dynamic response and parameter influence analysis of longitudinal slab trackpinThrough the analysis of the dynamic response of the track system,it can be seen that there is no obvious influence on the dynamic response of the track system with or without pins in the good state of the interlayer.When there is a gap between the layers,the pin anchoring measures can improve the limit ability of the track system and enhance the stability of the track structure.However,at this time,the pin bears pressure and pull-up force alternately,so there may be the risk of pin pull-out.The more pins are implanted,the more stable the track system is,and the stronger the limiting ability of the pin anchoring system is.The pull-up force and shear force of pins decrease with the increase of the number of pins,but the number reaches a certain degree,and the decrease range is small.Combined with the static analysis,it is suggested that the number of pins should not be too much,≤ 8 pins/plate.In the aspect of pull-out stiffness of anchor pin,the greater the pull-out stiffness of anchor pin,the stronger the limiting ability of anchor pin system,but the greater the vertical force borne by the pin,which is easy to cause the pin to be pulled out and cause the pin to fail.Combined with the static calculation,it is suggested that the pull-out stiffness of anchorage pin should be between 55 k N/mm-80 k N/mm.(3)Analysis of the influence of pin structure damage on macroscopic mechanical characteristics of longitudinal connection-pin systemWith the weakening of bond strength,the amount of arch on track slab tends to become larger.In practical application,the degree of pin damage(bond weakening of reinforcing bar adhesive)should be avoided to exceed 50%.In the aspect of single pin failure,the pin failure near the narrow joint defect has a stronger impact,and the failure of single pin will cause the uneven arch of the track slab,which will cause the unfavorable risk of eccentric compression of the structure.In the aspect of multiple pin failure,the vertical displacement of the longitudinal connection system will be large,but the influence of multiple pin failure on the upper arch position of the longitudinal connection system is not significant. |
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