轴载对广西大厚度柔性路面结构的力学响应规律分析

Analysis of Mechanical Response Laws of Axle Load to Large-Thickness Flexible Pavement Structure in Guangxi

为了研究广西大厚度柔性路面耐久性结构,本文依托田新高速公路项目的设计参数与交通条件,提出了一种广西大厚度柔性路面试验段结构。采用离散元软件进行了5种不同轴载下的力学响应规律及设计参数变化规律研究,为广西大厚度柔性沥青路面结构的应用推广提供重要参考。研究结果发现,对于所选大厚度柔性沥青路面结构的双圆荷载中心点处:随着深度的增加,各层顶部的竖向位移慢慢减小,但各层顶竖向位移、沿行车方向水平拉应力与压应变均随轴载的增加呈线性关系增加;拉应力增速路表 > 路基顶,压应力增速路表 > 中面层顶 > 下面层顶 > 基层顶 > 路基顶;拉应变增速路基顶 > 底基层顶 > 基层顶 > 下面层顶,压应变增速由大到小为路表 > 中面层顶;设计年限内车辙累计深度随轴载的增加呈线性增加,增速为8.585,超载易超过现有设计规范的车辙限值;沥青层疲劳开裂对应的累计当量轴载次数随轴载的增加呈指数减少,大厚度柔性路面结构沥青层疲劳寿命长,超载下也远高于常规沥青路面结构。

In order to study the durability structure of Guangxi’s large-thickness flexible pavement, a Guangxi large-thickness flexible pavement test section structure was proposed based on the design parameters and traffic conditions of the Tianxin Expressway project in this paper. The mechanical response law and design parameter change law under 5 different axle loads were studied using discrete element software, providing an important reference for the application and promotion of large-thickness flexible asphalt pavement structures in Guangxi. The research results found that at the center point of the double circular load of the selected large-thickness flexible asphalt pavement structure: as the depth increases, the vertical displacement at the top of each layer gradually decreases, but the vertical displacement at the top of each layer, horizontal tensile stress and compressive strain along the running direction all increase linearly with the increase of axle load;tensile stress growth rate of road surface > roadbed top, compressive stress growth rate of road surface > middle surface layer top > lower layer top > base layer top > roadbed top;tensile strain growth rate of subbase top > base top > lower layer top, and compressive stress growth rate from the highest to the lowest is road surface > middle layer top;during the design period, the cumulative depth of ruts increases linearly with the increase of axle load, with a growth rate of 8.585. Overloading can easily exceed the existing design specifications’ rut limits;the cumulative equivalent axle load number corresponding to fatigue cracking of asphalt layer decreases exponentially with the increase of axle load. The fatigue life of asphalt layer in large-thickness flexible pavement structure is long, and it is also much higher than that of conventional asphalt pavement structure under overload.