MECHANICAL ANALYSIS AND EVALUATION OF GRANULAR MATERIALS IN PAVEMENT STRUCTURES

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Granular material layers have not been considered to have high structural quality in pavement structures. The object of this project is to develop new analysis and evaluation methods of granular materials in pavement structure. For this purpose, the investigators have been divided into five groups and conducted their studies in collaboration among these groups. Outcomes of each group are as follows. Name(s) in parenthesis is(are) investigator(s) :Group A. Modeling granular base course (Nishizawa) : A program package for structural analysis of pavement based on three dimensional finite element analysis, Pave3D was developed. Extended SMP Criterion Modified Cam-clay model, which was developed by Group B, was incorporated into the Pave3D. Using the model, effects of permanent deformation of granular subbase in a concrete pavement was investigated. It was found that the permanent deformation of base course significantly increases concrete stresses.Group B. Modeling mechanical behavior of g … More ranular material (Koyanagawa, and Takeuchi) : Existence of permanent deformation of base course under concrete slab was confirmed from a repetitive loading experiment. Then to apply the Extended SMP Criterion Modified Cam-clay model to granular materials, triaxial compression test was conducted on a granular base course material and parameters required for the model were identified.Group C. Micro-mechanics of granular material (Murai) : Visualization of stress transfer path in granular material under compressive and shear tests was tried using the two dimensional photo-elastic test. From the results, effect of gradation on stress transfer path was investigated.Group D. Improvement of construction of granular base course (Hachiya) : New base course material was developed using reclaimed asphalt concrete stabilized with cement. Also, effects of water content, compaction degree and thickness on construction were investigated. The results revealed that the effect of water content is very small if compaction is sufficient.Group E. Structural evaluation of granular base course (Kamiura) : In order to precisely evaluate mechanical property of granular base course, applicability of compact FWD and PS layer inspection method were examined. It was found that both methods can be used for the evaluation and the difference between those two methods is very small. Less