基于综合稳定碎石土底基层沥青路面结构疲劳寿命分析

针对辽宁省部分地区砂石短缺的现状,通过在当地的天然碎石土中掺入碎石,设计了悬浮密实结构和骨架密实结构两种级配,选用水泥稳定和水泥土壤固化剂综合稳定两种稳定类型,并以7 d无侧限抗压强度为评价指标,综合经济性与可行性,优选3组可行方案,进而确定3组方案的最佳水泥剂量。基于辽宁地区公路典型沥青路面结构,结合路面结构的验算方法,利用Bisar软件对相关力学响应量进行计算,并拟合出各结构层疲劳开裂寿命与底基层厚度的关系。经计算分析得出:各结构层的疲劳开裂寿命随着底基层模量、厚度的增大而增大,而且与底基层厚度表现出较好的指数增长关系或线性相关关系;并通过疲劳寿命分析确定综合稳定碎石土可作为二级及二级以下公路中交通底基层和三级及三级以下重交通的基层。

Fatigue Life Analysis of Asphalt Pavement Structure Based on Comprehensive Stabilized Crushed Stone Subbase

In view of the current shortage of sand and gravel in some areas of Liaoning Province,two kinds of grading structures,such as suspended solid structure and dense structure of skeleton,were designed by incorporating gravel into the local natural gravel soil,and cement stability and cement soil curing agent were selected to be stable.A stable type,with 7 d unconfined compressive strength as the evaluation index,comprehensive economic and feasibility,three sets of feasible schemes are preferred,and the optimal cement dosage of the three sets of schemes is determined.Based on the typical asphalt pavement structure of highways in Liaoning Province,combined with the method of checking the pavement structure,Bisar software is used to calculate the relevant mechanical response,and the relationship between the fatigue cracking life of each structural layer and the thickness of the subbase layer is fitted.Through calculation and analysis,it is concluded that the fatigue cracking life of each structural layer increases with the increase of the modulus and thickness of the subbase layer,and it shows a good exponential growth relationship or linear correlation with the thickness of the subbase layer.Through fatigue life analysis,it is determined that the comprehensive stable gravel soil can be used as the subbase of the middle traffic below the second and the second grade and the basement of heavy traffic below the third and third grades in the highways.