动载作用下沥青路面的剪切破坏机理

Shear Destruction Mechanism of Asphalt Pavement Under Moving Load

为了研究移动荷载作用下沥青路面结构中剪应力场的分布规律,揭示沥青路面在动载作用下的剪切破坏机理,以便指导结构设计与养护对策的制定,建立了移动荷载作用下半刚性基层沥青路面动态响应三维有限元分析模型,系统分析了汽车在正常行驶与制动状态下结构层竖向位移及剪应力的动态响应规律,并将动载下计算结果与静载下计算结果进行了对比。结果表明:在汽车匀速行驶状态下,结构层最大竖向位移、最大竖向剪应力及最大水平剪应力均有所降低;在汽车制动状态下,结构层最大竖向位移、最大竖向剪应力增加不显著,但最大水平剪应力增加显著,且随水平力系数及轴载的增大而增大,此时如果仍按照静力模式来设计混合料的抗剪强度,可能会导致抗剪强度不足而使路面出现车辙、拥包及推挤等早期损坏现象。

In order to study the distributing rule of shear stress in the asphalt pavement structure under moving load and disclose the shear destruction mechanism which is easy to design the pavement structure and frame the maintenance countermeasure,3-D finite element analysis model of dynamic response of semi-rigid base asphalt pavement under moving load was established.Dynamic response rules of road surface acted by vehicle running at common speed and at the state of braking on the basis of 3-D dynamic finite element analysis model were analysed.The contrasts between dynamic and static analyses were caried out.The results show that the maximal vertical displacement,maximal vertical shear stress and maximal horizontal shear stress are all reduced when the vehicles run at common speed,but the maximal horizontal shear stress increases greatly under the state of braking,and it will increase with the increase of the horizontal force coefficient and axle load,so shear destruction,such as swell,rut will occur if the shear strength of asphalt mixture is designed by static model.