基于ISS&SSDR的沥青路面层间疲劳寿命外因素综合影响预估

Estimation of Comprehensive Impact of External Factors on Interlayer Fatigue Life of Asphalt Pavement Based on ISS&SSDR

目前沥青路面层间疲劳性能的评估高度依赖于疲劳寿命,但现有层间疲劳寿命模型中考虑的因素不够全面,且层间疲劳模型与初始剪切模量之间缺乏关联性。本研究进行了4种外因素条件下(即:剪切应力幅值、温度、加载频率、压应力)的小梁四点剪切疲劳试验,获取了路面层间的初始剪切模量(ISS)与剪切模量衰变速率(SSDR),分别建立了ISS与SSDR的非线性多元回归模型,并综合ISS、SSDR双指标形成层间疲劳寿命Nf预测模型。结果表明:①各因素对层间ISS的影响排序为:温度>剪切应力幅值>加载频率>压应力;各因素对层间SSDR的影响排序为:压应力>温度>剪切应力幅值>加载频率;各因素对层间疲劳寿命的影响排序为:温度>压应力>剪切应力幅值>加载频率;②基于ISS与SSDR构建的层间疲劳寿命Nf的表达模型,实现了外因素综合作用下疲劳寿命Nf、ISS、SSDR三指标相互关联。研究成果为层间疲劳寿命预估提供一种新途径,为加强层间设计提供理论支撑。

The evaluation of interlayer fatigue performance of asphalt pavement is highly dependent on fatigue life.But the factors considered in the existing interlayer fatigue life prediction model are not comprehensive enough,and there is no correlation between the interlayer fatigue life prediction model and the initial shear stiffness.In this study,four-point shear fatigue tests under four external factors(i.e.shear stress amplitude,temperature,loading frequency,normal stress)were carried out and Initial Shear Stiffness(ISS)and Shear Stiffness Decay Rate(SSDR)of interlayer performance were obtained.Nonlinear multiple regression models for ISS and SSDR were established,respectively.And an interlayer fatigue life Nf prediction model was constructed based on ISS and SSDR.The results show that:(1)the influence degree of four external factors on the interlayers ISS ranks:temperature>shear stress amplitude>loading frequency>normal stress;the influence degree of four external factors on the decay rate of interlayer shear stiffness ranks:normal stress>temperature>shear stress amplitude>loading frequency;the influence degree of four external factors on interlayer fatigue life ranks:temperature>normal stress>shear stress amplitude>loading frequency;(2)the interlayer fatigue life Nf prediction model based on ISS and SSDR realizes the correlation among the three indexes of the interlayer fatigue life Nf,ISS and SSDR.The research results provide a new way for the prediction of interlayer fatigue life and a theoretical support for strengthening interlayer design.