轮载作用下典型沥青路面结构力学行为分析

摘要

为分析比较半刚性基层、倒装式和组合式3种典型沥青路面结构受轮载作用的力学行为,依托成德南高速公路沥青路面工程试验段,在与贝克曼梁路表静态弯沉测试值对比的基础上,开展了基于弹性层状体系理论的静力学分析.现场选取3个断面,通过预埋沥青应变计测试了不同轴重、不同车速条件下的车辆移动轮载动力响应.研究结果表明:沥青路面更易出现横向疲劳开裂;倒装式沥青路面面层层底行车方向及横断面方向拉应变峰值分别对应为组合式沥青路面的1.24倍和1.30倍,为半刚性基层沥青路面的2.37倍和2.67倍;路面结构厚度相同的情况下,半刚性基层沥青路面在减少沥青面层本身的疲劳开裂和永久变形方面优势较强,组合式沥青路面与半刚性基层沥青路面受力情况接近,可部分替代半刚性基层沥青路面;倒装式沥青路面轴重敏感度为3种路面结构中最小,但宜适当增加沥青面层或沥青稳定碎石基层厚度以改善其受力状况,并应严格控制沥青稳定碎石基层拉应力,以减少倒装式沥青路面和组合式沥青路面疲劳破坏.%The mechanical behaviours of three typical asphalt pavements including semi-rigid base,inverted and composite asphalt pavement under wheel loads were analyzed and compared based on the tests on the asphalt pavement test section constructed in Chengdu-Deyang-Nanchong expressway.Comparing with static deflection of pavement surface obtained by Beckman beam test,static analysis based on elastic multi-layered theory was carried out.Pre-plugged asphalt strain gauges were used for the three asphalt pavement test section to measure in-situ dynamic responses caused by moving vehicle with different axle loads or at different speeds.The results show that fatigue cracking is more likely to appear in the transverse direction of asphalt pavement.The peak values of tensile strain in the vehicle traveling direction and the transverse direction of bottom of inverted asphalt surface are respectively 1.24 and 1.30 times those of composite asphalt pavement,and 2.37 and 2.67 times those of semi-rigid base asphalt pavement respectively.For pavement structures of the same thickness,semi-rigid base asphalt pavement has great advantage in decreasing fatigue cracking of asphalt surface and permanent deformation,and the force bearing capacity of the composite asphalt pavement is close that of the semi-rigid base asphalt pavement,which thus can be replaced by the composite asphalt pavement partially.Although the inverted asphalt pavement is less sensitive to axle load than other pavement structures,the thickness of its asphalt surface or asphalt treated base should be increased appropriately to improve force bearing capacity,and moreover the tensile stress of the asphalt treated base should be controlled strictly to decrease the fatigue damage of the inverted and composite asphalt pavements.