双重界面增强型沥青路面结构力学响应特性

Mechanical Response Characteristics of Dual Interface Enhanced Asphalt Pavement Structure

为合理指导半刚性基层沥青路面层间黏结设计,文中基于不黏轮乳化沥青与纤维碎石封层设计双重界面增强型结构,提出基于斜剪试验的界面摩擦系数增量模型,合理确定不同界面增强措施的摩擦系数范围。通过建立三维动力有限元模型,并将纤维碎石封层进行二维壳单元复合接触仿真设计,研究了结构的空间-时变力学响应规律、力学响应对于封层模量的敏感性,以及6种层间黏结设计的结构对比分析,结果表明,结构水平拉应力、剪应力呈现“界面多峰”特征,最大剪应力峰值在结构层3个界面附近,峰值大小相对均衡;沥青层剪应力、沥青层层底拉应变,以及路表弯沉对纤维碎石封层模量敏感性强,2 000 MPa为封层模量的最适设计参数;相较于其他5种常规层间黏结措施,本设计结构呈现沥青层间低剪应力、层底低拉应变,以及半刚性层层底低拉应力特点的优良力学特性,有利于减少沥青层开裂、基层开裂及其反射裂缝、失稳型车辙等,具备处理半刚性基层沥青路面层间问题的良好技术潜质。

To reasonably guide the design of interlayer bonding of semi-rigid base asphalt pavement, a dual-interface reinforced structure is designed based on non-stick wheel emulsified asphalt and fiber gravel seal, an incremental model of interfacial friction coefficient is proposed based on oblique shear test, and the range of friction coefficients for different interfacial reinforcement measures is reasonably determined. By establishing a three-dimensional dynamic finite element model and subjecting the fiber gravel seal to a two-dimensional shell unit composite contact simulation design, the spatial-time-varying mechanical response of the structure, the sensitivity of the mechanical response to the modulus of the seal layer and the comparative analysis of the six interlayer bonding designs are studied. It is concluded that the horizontal tensile stress and shear stress of the structure show “interface multi-peak” characteristics, the maximum shear stress peak is near the three interfaces of the structural layer, and the peak values are relatively balanced. The shear stress of asphalt layer, tensile strain at the bottom of asphalt layer and road surface deflection are highly sensitive to the modulus of fiber gravel seal layer, and the most appropriate design parameter for the modulus of seal layer is 2 000 MPa. Compared with the other five conventional interlayer bonding measures, this design structure presents excellent mechanical characteristics of low shear stress between asphalt layers, low tensile strain at the bottom of layers and low tensile stress at the bottom of semi-rigid layers, which is conducive to reducing asphalt layer cracking, base layer cracking and its reflection cracks, and unstable rutting. It has good technical potential to deal with interlayer problems of semi-rigid base asphalt pavement.