Research On Rebound Modulus Evolution Characteristics Of Semi-rigid Base Materials In Qing-ao Section Of Lin-ha Line

Currently,the semi-rigid base layer has a high strength and a strong load-diffusing ability and is widely used as an asphalt road base layer.The domestic use of the static modulus method for the elastic modulus of semi-rigid base materials in the design stage,and doesn't consider the evolutionary behavior of the material modulus during service life,modulus parameters are more optimistic.Therefore,it's of great scientific significance and application value to conduct in-depth research on the evolution law and parameter values of resilient modulus of semi-rigid base in service.This article originated from Inner Mongolia Communications Department Construction Science and Technology Project(NJ-2014-019),this article takes a 2km semi-rigid base test road as a research object,and combined with field test road data acquisition system,and the study focuses on the decay characteristics of the semi-rigid base modulus during the service period.The main research results are as follows:(1)Affected by the slope,the semi-rigid base temperature of the asphalt pavement in the test section is unevenly distributed along the transverse direction.Concept of slope impact factor was put forward to quantify the degree of influence of different seasonal road slopes on grassroots temperature distribution,the test results show that the winter slope has a greater influence on the road base temperature distribution than the summer.Through the analysis of the relationship between temperature and strain in the base layer,the equation of strain and temperature in the base layer is established.The principle of temperature equivalence is adopted to obtain the development law of the base strain under the vehicle load.(2)Based on the fatigue damage theory,the semi-rigid material modulus and strainevolution model was deduced,and the model was comprehensively evaluated based on the in-service road data in Inner Mongolia.The model for the semi-rigid material modulus decay and strain development model was recommended.Combining with the actual measurement of the basement modulus and strain data at the test road site,the least squares method was used to estimate the relevant parameters in the model.The modulus evolution equation and the strain evolution equation of the test road base were obtained,and the fatigue life of the test road base was predicted,forecast results show that the estimated life of the base layer is lower than the design life(3)Taking the semi-rigid base modulus decay equation of test roads and Inner Mongolia roads as the research object,the evolution law of semi-rigid base material modulus during service period is analyzed.The results show that during the service period,the semi-rigid base layer modulus is divided into three stages: the first stage rapid decay of the modulus,accounting for about 5~10% of the total service life;The second stage of the smooth decay,accounting for about 70~80% of the total service life;The third stage modulus accelerates decay until the material is destroyed.(4)Using the three-phase decay rule of the semi-rigid base material during service period and the selection of parameters using the second-stage modulus decay range as the effective modulus value,and comprehensive correction of parameters by semi-rigid base material laboratory test,given the resilience modulus of semi-rigid base materials in the Lin-Ha Line and parts of Inner Mongolia.