循环温度荷载下无砟轨道结构模型试验研究

为研究循环温度荷载下无砟轨道结构层间离缝产生与扩展规律,以及离缝对轨道结构受力性能的影响,制作了三跨无砟轨道-简支梁桥结构1/4缩尺模型,开展了18次循环温度荷载试验。并在循环温度试验前后分别对结构进行了2次静力加载试验,对比分析结构体系受力特性发生的变化。试验结果表明:循环温度荷载作用下,梁端处轨道板与CA砂浆之间产生离缝,并向跨中呈“阶梯状”逐渐延伸,历经萌生、扩展和稳定三个阶段。随离缝长度增加,相同温度荷载下,梁体上拱度逐渐减小,而轨道结构上拱度逐渐增大,在离缝的萌生、扩展和稳定三个阶段,轨道结构的刚度呈现慢-快-慢的速度逐渐减小。经18次循环温度荷载作用后,轨道结构的刚度降低了14. 96%,无砟轨道-桥梁结构体系整体刚度降低了2. 52%。

Model Experiments of Ballastless Track-bridge Structure under Cyclic Temperature Load

In order to study the law of interface seam generation and expansion of ballastless track structure under cyclic temperature load,and the influence of disengagement on the mechanical performance of track structure,a quarter scale model of three-span ballastless track-simply supported beam bridge was made,and 18 cyclic temperature load tests were carried out.Two static loading tests were carried out before and after the cyclic temperature test to compare and analyze the changes of the mechanical characteristics of the structural system after the cyclic temperature test.The results show that under the action of cyclic temperature load,the interface seam between the slab and CA mortar at the end of the beam is generated and gradually extends to the middle of the span in a"ladder"shape,undergoing three stages of initiation,expansion and stabilization.Under the same temperature load,with the increase of the distance between layers,the camber of the beam decreases gradually,while the camber of the track structure increases gradually.In the three stages of initiation,expansion and stabilization of the interface seam,the stiffness of the track structure exhibits a gradual reduction of slow-fast-slow speed.After 18 cycles of temperature loading,the stiffness of the track structure is reduced by 14.96%,while the overall stiffness of the ballastless track-bridge structure system is reduced by 2.52%.