CRTSⅢ型板式无砟轨道横向弯曲疲劳试验

Fatigue Testing of CRTS Ⅲ Ballastless Slab Track Structures under Transverse Bending

为了研究列车疲劳荷载作用下CRTSⅢ型板式无砟轨道结构横向受力性能,采用实际工程施工现场的材料及施工工艺,利用足尺模型,切割制作6个单承轨台或双承轨台的板式无砟轨道试件,进行橡胶板模拟路基上板式无砟轨道结构的横向弯曲疲劳试验,得出列车疲劳荷载引起的横向弯矩作用下板式轨道试件的应力、变形分布规律及疲劳损伤的发展形态.试验结果表明,在15.0~255.0 kN和42.5~425.0 kN疲劳荷载作用下,模拟路基上单承轨台和双承轨台的试件板中位置轨道板上表面先出现纵向裂缝,随后轨道板横向预应力筋锚固端出现由锚头向轨道板上表面的劈裂裂缝,累计疲劳500万次后,三点弯曲模式下轨道板-充填层复合板试件的自密实混凝土开裂荷载和层间滑移荷载分别减小20%~30%和25%以上,疲劳损伤、层间离缝对轨道板与充填层的协同工作性能有不利影响.

To investigate the transverse mechanical performance of CRTS Ⅲ slab ballastless track structures under the cyclic action of train loads, a full-scale CRTS Ⅲ slab track structure was fabricated using the s a me materials and technology as that employed in practical on-site construction applications. Six slab track specimens with one or two sleepers were fabricated from the full-scale slab track structure. Fatigue tests under transverse bending were conducted on these slab track specimens supported on rubber plate-simulated subgrades. T h e characteristics of stress distribution, deformation distribution, and nature of development of fatigue d a m a g e on slab tracks subjected to transverse bending were determined from the fatigue tests. T h e fatigue test results indicated that longitudinal cracks first appear on the top surface of the track slab in the middle of the slab track specimens with one or two sleepers under fatigue cycles of 15. 0 - 255. 0 k N and 42. 5 - 425. 0 k N,respectively. Several splitting cracks subsequently developed from the transverse prestressing tendon to the top surface of the track slab on the profile of anchorage e n d. After cumulative 5 million fatigue cycles,theloads for a composite plate with a track slab-infilling layer under the three-point bending modecorresponding to self-compacting concrete （SCC ） cracking and interlayer bond-slip reduced by 20% - 30% and more than 25% , respectively. It can be concluded that fatigue d a m a g e and interlayer delamination have adverse effects on the cooperative working performance of the track slab and the S C C infilling layer.