含碎石层沥青加铺结构外部耦合计算方法

Coupling calculation method for asphalt overlays on rubblized portland cement concrete slab

碎石化沥青加铺路面结构中不同层位材料性质差异显著,难以由同一种力学模型加以描述。针对这一问题,将沥青加铺层及碎石化混凝土视为连续及非连续颗粒介质,分别采用有限差分法(DEM)与颗粒离散单元法(PCC)模拟沥青加铺层及碎石结构层的力学行为,并采用耦合的方式,通过两域对应边界的相容条件与平衡条件的控制,实现了连续域与离散域的平滑过渡。作为应用,结合现场情况,将破碎混凝土简化成碎粒层、碎石表层和碎石底层,通过模拟计算,分析了破碎粒径不同组合条件下沥青加铺层对荷载的响应。结果表明,碎粒层粒径越大,沥青层的拉应力、应变越大;碎石表层粒径越小,即多锤头破碎机(MHB)破碎的越碎,原水泥混凝土面板的强度下降的越多,整体性就越差,沥青层底的拉应力、应变也就越大,因此要将破碎状态控制在一定程度为宜。

For the structure of asphalt overlays on rubblized portland cement concrete（PCC） slab,properties of materials in each layer vary greatly.It is therefore not proper to be simulated by one mechanical model.For this reason,a numerical method which combines the finite difference and discrete element method（DEM） is proposed;in which the rubblized PCC slab is described using DEM while the asphalt overlays is simulated by the finite difference method.For purpose of smooth transition between continuous and discontinuous domains,conditions of compatibility and equilibrium along the corresponding boundaries need to be satisfied in the computation process.To illustrate the effects of rubblization more clearly,the rubblized PCC slab is further divided into three sublayers as the small particles layer,the surface layer and bottom layer.The mechanical response of the interaction between the rubblized PCC slab and overlays is discussed through varied the particles sizes.The results have shown that the tensile stress and strain at the bottom of the asphalt overlays are proportional to the particle size of the small particles layer.It is also found that the smaller the particles size of the surface layer is,the larger the tensile stress,strain are.In other words,strength loss of the old PCC is proportional to degree rubblization of the slab.This shows that the degree of rubblization should be properly controlled.