道床板钢筋锈蚀的细观力学影响

为探究钢筋锈蚀对双块式无砟轨道道床板混凝土的影响，建立了道床板混凝土细观尺度力学模型，研究了钢筋锈蚀时不同钢筋直径、间距、保护层厚度的道床板受力性能及损伤破坏模式，分析了列车荷载和温度荷载对锈胀钢筋混凝土道床板力学性能的影响. 研究结果表明:钢筋锈蚀引起的道床板开裂模式主要与钢筋保护层厚度有关，与钢筋直径和间距关系小；道床板内部裂缝贯通时的锈胀位移随着钢筋间距的增大而增大，当保护层厚度为60 mm，钢筋间距为120 mm时，61.2 μm的钢筋锈胀位移就会引起道床板内部裂缝贯通；列车荷载对锈蚀后的道床板损伤影响小，且会使道床板受力趋于均匀；整体降温30 ℃和负温度梯度荷载均会使锈胀道床板拉伸损伤进一步明显增大，在道床板水平及垂向产生贯通裂缝；整体升温30 ℃和正温度梯度荷载作用对锈胀道床板损伤影响小. 

Meso-mechanical Effect of Track Slab Rebar Corrosion

To explore the effect of rebar corrosion on double-block ballastless track slab concretes, a meso-scale mechanical model of track slab concretes was built to study the mechanical properties and damage modes of the slabs with different rebar diameters, spacing and cover thicknesses, the effect of train and temperature loads on the mechanical property of reinforced concrete track slabs with corrosion was analyzed. The results show that the cracking mode of track slabs induced by rebar corrosion mainly depends on the thickness of rebar cover but rarely relies on the diameter or spacing of rebar. In the event the internal cracks of the slabs connect together, the expansion displacement of rebar increases with the increase of the rebar spacing. When the cover thickness is 60 mm and the rebar spacing is 120 mm, the rebar corrosion displacement of 61.2 μm would result in the internal coalescence cracks. The train load has little effect on the slabs with corrosion crack, and may make the stress on the slabs tend to be uniform. The temperature cooling of 30 °C and the negative temperature gradient may cause the further significant increase of the tension damages of slabs with corrosion, at the same time it may cause the coalescence cracks through along the horizontal and vertical directions of slabs. The temperature rise of 30 °C and the positive temperature gradient barely have effect on the damages of the track slabs with corrosion.