摘要：Unbound granular materials are widely used in the base and subbase layers of pavement systems. Currently, the compaction quality assurance (QA) of unbound granular base is mostly density-based with many drawbacks and is to be replaced by modulus-based QA. The Light Weight Deflectometer (LWD) test, which is often used to determine the stiffness of unbound granular materials, is a promising tool for modulus-based compaction QA but needs a more fundamental understanding of its experimental configuration and data interpretation. We build a digital model that adopts a discrete element method to model LWD field tests and account for the effects of moisture and finer particles by adopting a modified Hertz contact model which includes a component of attractive force. We investigate the relations between microscopic parameters and macroscopic material properties qualitatively, finding that the LWD modulus increases with model suction which is reversely related to moisture content, or interparticle friction which is reversely related to fine content. We calibrate this model using test results from field LWD tests. From the modeling results, we observe a trend of decreasing stiffness with increasing moisture or fine particle content, which agrees with existing experimental data. With the quantitative relations obtained from calibration, the model can be used to predict the LWD modulus of unbound granular base.
关键词：discrete element modeling; lightweight deflectometer; pavement engineering; unbound granular base
