往复荷载作用下WJ-8扣件纵向阻力试验研究

Experiment Research on the Longitudinal Resistance Test of WJ-8 Fastener under Reciprocating Load

研究目的:在温度作用下,简支梁桥梁体会发生热胀冷缩,长期作用下将导致桥上无砟轨道梁端扣件系统发生破坏,严重时将不能满足线路的功能要求。本文通过往复加载试验模拟温度效应下32 m简支梁桥梁端扣件破坏过程,以此研究轨下垫板滑出过程机理及其对扣件纵向阻力的影响。研究结论:(1)随着对轨道加载试验次数的增加,2 mm位移对应的扣件纵向阻力先增加随后波动式降低,扣件滑移阻力先增加后逐渐减小,而垫板窜出位移量持续增大,可以预测当加载工作继续进行时,2 mm位移对应扣件纵向阻力及滑移阻力将继续减小;(2)随着垫板窜出位移量的增加,2 mm位移处扣件纵向阻力先增加后缓慢减小,扣件滑移阻力先有所增加而后逐渐减小;(3)扣件垫板窜出过程中,垫板纵向拉长,厚度减小,弹性降低,轨下橡胶垫板的弹性位移逐渐减小,且钢轨更易产生滑移;(4)在往复加载过程中,影响扣件纵向阻力的因素有两个:垫板表面的粗糙度及垫板窜出位移量,前期阶段垫板表面的粗糙度为主要影响因素,而后期阶段垫板窜出位移量影响更大;(5)本研究成果对于指导无砟轨道线路扣件的养护维修具有一定的参考意义。

Research purposes： Under the influence of temperature,the beam body of the simply supported beam bridge experiences thermal expansion and contraction,it will lead to the fastener destruction of the ballastless track on the bridge terminal under long-term influence,then will not be able to meet the functional requirements of the line if it is serious. In this paper,the fastener destruction process on the 32 m simply supported beam bridge terminal is simulated by the reciprocating loading test,so as to study the mechanism of the sliding process of rubber pad and the influence on the longitudinal resistance of the fastener.Research conclusions：（ 1） With the increase in the times of track loading test,the longitudinal resistance of the fastener corresponding to the 2 mm displacement increases firstly and then decreases in volatility,the sliding resistanceof the fastener also increases firstly and then decreases,and the displacement of the sliding of rubber pad increases continuously. It can be predicted that when the loading work continues,the longitudinal resistance corresponding to the2 mm displacement and sliding resistance of the fastener will continue to decrease.（ 2） With the increase in the displacement of the rubber pad,the longitudinal resistance of the fastener corresponding to the 2 mm displacement increases firstly and then decreases slowly,and the sliding resistance of the fastener increases firstly and then gradually decreases.（ 3） In the sliding process of the rubber pad,the rubber pad is elongated in the longitudinal direction,thickness is decreased and the elasticity is deduced,the elastic displacement of the rubber pad is gradually reduced,and the rail is more prone to slip.（ 4） In the reciprocating loading process,there are two factors that affect the longitudinal resistance of the fastener： the roughness of the surface of the rubber pad and the displacement of the sliding of rubber pad. The roughness of the surface of the rubber pad is the main influencing factor in the early stage,and the displacement of the sliding of rubber pad has a greater impact in the late stage.（ 5） The research results have a certain reference significance for guiding the maintenance and repair of the fasteners of ballastless track.