室温蠕变对WJ-7型无砟轨道扣件扣压力损失的试验研究与分析

Research and Analysis of Impact of Creep at Room Temperature on Toe Load Loss of WJ-7 Ballastless Track Fastener

扣件技术是无砟轨道结构关键技术,为保证行车绝对安全和旅客乘坐的舒适性,要求钢轨扣件具有足够的扣压力,文章通过试验研究蠕变对WJ-7型扣件扣压力损失的影响.分别进行保持扣件变形不变与保持初始扣压力不变的两组(各5套扣件)试验,在组装好的扣件相应位置埋设压应力传感器以测量扣件扣扣压力,在保持一定扣压力情况下,用T型螺栓螺母位移的变化表示弹条的蠕变变形量,对比分析两种情况下扣件蠕变规律及其对扣压力的影响.试验表明:在初始扣压力为10 k N,分别保持扣件弹条变形不变和保持扣件扣压力不变情况下,弹条蠕变分别为1.45 mm和2.12 mm,若都转化成扣压力的损失,则分别为1.00 k N和1.46 k N,且二者蠕变都是前期快后期慢,但后者蠕变时间更长,且蠕变量更大.理论分析还表明:应力水平对蠕变影响很大,应力水平大,蠕变发展迅速.

The fastener technology is the key technology of structure of ballastless track.In order to ensure the abso-lute driving safety and the passengers’ride comfort,the fastener of steel track is required to have enough toe load of fastening.The research on the impact of the creep on loss in the toe load of WJ -7 ballastless track is carried out in this paper.Respective tests are carried out for two groups of fasteners （5 sets of fasteners for each）with unchanged deformation of fasteners and unchanged initial toe load of fastening,embedded with the pressure sensor and stress sen-sor in the positions corresponding to the assembled fasteners to measure the toe load of fastening.Under the circum-stances that certain toe load is kept,the change in displacement of T bolts and T nuts are used to indicate the creep deformation of the elastic bar,and the creep rule of the fastener and its impact on the toe load of fastening under two circumstances are compared and analyzed.It is shown through the experiment that when the initial toe load is 10 kN with deformation of fastener elastic bar and toe load of fastener remaining unchanged respectively,the creeps of elastic bar are 1.45 mm and 2.12 mm respectively.If converted to the loss in toe load,the creeps are 1.00kN and 1.46 kN respectively.In addition,both of the creeps are fast in the early stage and slow in the later stage,but the creep time of the latter is longer,with larger creep deformation.The theoretical analyses also indicate that stress level has great influence on the creep,if stress level is high,the development of creep will be rapid.