低温荷载下沥青路面线性损伤特性分析

摘要

Fatigue damage characteristics of asphalt pavements under thermal load repetitions were investigated using a general−purpose finite element software ABAQUS and the associated material subroutine programs. An asphalt pavement numerical model considering the pavement material fatigue damage was established to obtain the spatial distribution and evolution of the asphalt pavement structural damage, in which the horizontal normal stresses were determined. The results show that the pavement structural damage mainly occurs in asphalt surface course. An increasing thermal load repetitions leads to accumulated damage increase at a decreasing damage rate for the asphalt surface course. Damage increases by 0.09 when temperature changing times change from 1 000 to 2 000, and increases by 0.012 when temperature changing times change from 9 000 to 10 000. The damage in the asphalt surface course increases with the increase of temperature variation that is the difference between the highest and the lowest temperatures. Damageincreases by 0.033 when temperature variation changes from−2℃to−4℃, and increases by 0.154 from−8℃to−10℃. Based on the stress spatial distribution results, the horizontal normal stresses are reduced due to the damage occurring in the asphalt layer. The reduction of the horizontal normal stresses becomes more significant when it is close to top surface of the asphalt layer. The stress is 0.265 6 MPa at the level of 6 cm above the bottom of surface layer, 0.290 9 MPa at 12 cm, and 0.279 7 MPa at 18 cm. With the increase of the thermal load repetitions, the horizontal normal stresses at the surface of the asphalt layer decrease at a decreasing rate. However, they increase and then decrease with the increase of the temperature variations.%为了研究沥青路面结构在温度荷载作用下的疲劳损伤特性，运用通用有限元软件ABAQUS及其二次开发平台，建立考虑路面材料疲劳损伤模型的沥青路面结构数值计算模型，分析沥青路面在温度荷载反复作用下路面结构损伤的空间分布及演化规律、路面结构水平正应力的空间分布与演化规律。研究结果表明：路面结构损伤主要分布在沥青面层，且面层表面损伤度随着温变次数的增大而逐渐增大，但增大的幅度逐渐减小，当温变次数从0.1万次增大到0.2万次时，损伤度增大0.09，但当温变次数从0.9万次增大到1.0万次时损伤度只增大0.012；面层表面损伤度随着温变幅度的增大而增大，且增大的幅度增大，当变幅从−2℃变为−4℃时，损伤度增大0.033，当变幅从−8℃变为−10℃时，损伤度增大0.154；从面层内的空间分布来看，有损路面与无损路面相比，水平正应力有所减小，且越是靠近面层表面减小的幅度越大，距面层层底6 cm处，应力为0.2656 MPa，12 cm处为0.2909 MPa，18 cm处为0.2797 MPa；随着温变次数增大，面层表面的水平正应力逐渐减小，减小幅度逐渐减小；随着变温幅度增大，面层表面的水平正应力先增大、后减小，有1个峰值点。