冲击碾压动荷载下水泥混凝土路面结构的力学行为

为了揭示冲击碾压动荷载下水泥混凝土路面结构的力学行为,基于动力三维有限元分析方法,考虑材料的弹塑性,拟定纵横板边、板中及板角4种典型荷载位置,在四楞冲击压路机冲击碾压水泥混凝土路面时,分析了路面各层结构的受力和变形特征。研究发现,各工况下混凝土板底部承受纵、横向弯拉应力是旧面板破裂的主要原因,基层与旧面板一起处于双向弯拉状态,土基三向受压,不同工况存在不同的有效影响深度。冲击碾压板角时,路面板竖向位移最大,影响深度最深;而冲击板中位置时,板竖向位移最小,分布最均匀,此时板体以纵向弯拉为主,易形成横向裂缝;当冲击纵向板边时,板体以横向弯拉为主,易形成纵向裂缝。可见,路面破碎效果是地基刚度、冲击能量与冲击位置的综合函数,建议基于具体路况选择相应的施工方案。

Mechanical behaviors of cement concrete pavement structure under impact rolling load

In order to explain the mechanical behaviors of cement concrete pavement structure under impact rolling load,four typical loading positions were considered such as slab longitudinal side,slab transverse side,slab corner and slab center,the stress and deformation characteristics of pavement structures under the impact load of quadrilateral impact roller were studied based on 3D elastic-plastic dynamic finite element method.Analysis result indicates that the main reasons of old cement concrete pavement cracking in different cases are that the bottom of cement concrete pavement bears longitudinal flexural-tensile stress and transverse flexural-tensile stress,both base course and old slab appear flexural-tensile state in two directions,while subgrade is in three dimension compressive stage,and the effective influence depths are different in different cases.The vertical displacements of slab and influence depths are maximum when the load locates at slab corner,while the vertical displacements of slab are minimum and uniform when the load locates at slab center.Pavement slab is in longitudinal bending stage and easily forms transverse cracks when the load locates at slab center,while pavement slab is in transverse bending stage and easily forms longitudinal cracks when the load locates at slab side.So the cracking effect is a synthetic function of foundation stiffness,impact energy and impact location,it is reasonable that constructing scheme is chosen according to different road conditions.