荷载-温度耦合作用下土工布防治反射裂缝效果试验研究

Research on the Effects of Geotextile on Preventing and Controlling Reflection Cracks under Load-Temperature Coupling

反射裂缝是半刚性基层沥青路面的常见病害形式之一,采用土工布防治反射裂缝是一种较为经济的措施,但在荷载-温度耦合作用下的实际效果需进一步验证。根据车辆荷载和温度变化均造成面层层底受拉的特点,将温度变化等效为竖向荷载,通过数值模拟确定荷载幅值比例关系,以两个不同频率和幅值荷载的组合模拟荷载-温度耦合作用,使用MTS试验仪对4种不同车辆荷载-温度荷载组合下土工布防治反射裂缝效果开展疲劳试验研究。结果表明,反射裂缝扩展速度随温度荷载占比增大而增大。在4种不同车-温比例下,土工布可使裂缝初裂疲劳次数提高72%~152%,使相同荷载作用次数下的裂缝张开量减小5%~26%。温度荷载占比越高,土工布对延缓初裂和减小裂缝张开量的贡献越大,其防治反射裂缝贡献的发挥依赖于自身的拉伸程度;面层底面初始变形越大,土工布越早发挥作用。

Reflective cracks are one of common disease forms of semi-rigid base asphalt pavement.It is an economical measure to use geotextiles to prevent reflection cracks,but the actual effect under load-temperature coupling needs to be further verified.In this paper,according to the characteristics that both the vehicle load and the temperature change cause the surface layer to be in tension,the temperature change is equivalent to a vertical load,and the proportional relationship of the load amplitude is determined by numerical simulation,and the combination of two different frequencies and amplitude loads are used to simulate the load-temperature coupling effect,the MTS tester is applied to carry out fatigue test on the effect of geotextiles on preventing reflection cracks under four different vehicle load-temperature load combinations.The results show that the propagation velocity of reflective cracking increases with the increase of the proportion of temperature load.Under four different vehicle-thermal ratios,geotextile can increase the initial crack fatigue cycles by 72%-152%,and reduce the crack opening under the same load cycles by 5%-26%.As the proportion of thermal load increases,the contribution of geotextile to delay the initial crack and reduce the crack opening becomes greater.The exertion of the anti-reflective cracking contribution of geotextile depends on its own tensile deformation degree.With larger initial deformation in the bottom of the surface layer,the geotextile will contribute earlier.