基于主应力分析的高模量基层沥青路面破损机理研究

Damage Mechanism of Asphalt Pavement with High Modulus Basement by Principal Stress Method

利用均匀设计安排参数组合对高模量基层路面结构应力分布进行了有限元计算,并利用莫尔圆分析了高模量基层路面结构中不同深度的应力状态,重点对比了不同位置不同深度各点的主应力组成方式,并观察到高模量基层路面表层各点的主应力组成方式出现拉-压复合剪切现象。认为:(1)拉-压复合剪切状态的存在,使得路面在疲劳荷载作用下,有两种接近路面材料临界物态线的方式,拉-压复合剪切状态是不同温度下TOP-DOWN裂纹与车辙破坏的重要诱因之一,疲劳状态下各点主应力组成方式不同,对路面结构的疲劳寿命有重大影响;(2)莫尔包络线可以简化为由内聚力c和抗拉强度σt控制。未来,高温条件下的内聚力c和抗拉强度σt有可能作为路面材料拉剪疲劳控制指标。

The stress states of asphalt pavement with high modulus basement are caIculated with finite element models in which the parameters input are arranged with Uniform Design method. Mohr circle method for two-dimensional stress system is applied to analysis the calculation results. The positions of Mohr circles for different nodes of two-dimensional stress systems are contrasted. Biaxial compression/tension phenomenon on pavement surface is found, in which case the stress circle extends into both positive and negative a space. The results show. Biaxial compression/tension phenomenon makes it possible there are at least two stress paths for pavement material to reach the strength envelopes under fatigue loadings. Biaxial compression/tension phenomenon is one of the key reasons for both TOP-DOWN cracking and rutting. Under fatigue loading, the positions of Mohr circles on different stress state under the pavement have great influence on fatigue life of pavement. Because the strength envelopes can be determined by cohesive, c, and tension strength,σt, both of them can be used as alternative design parameters together for evaluating pavement material anti-shear characteristic.