Triaxial shear test of road surface/base layer waste materials with optimization of its model prediction
In order to investigate the engineering characteristics of aged and abandoned surface asphalt milling planning material and face-base mixed milling material in road engineering and the corresponding prediction optimization constitutive model,and to promote its reapplication in engineering,with the help of a large triaxial shear test system,respectively,the peripheral pressure for the 100,200,300,400 kPa,the change rule of the strength and deformation of the test material were tested.The deviatoric stress-axial strain characteristics and volumetric strain-axial strain characteristics of the three test materials were also analyzed,on the basis of which the shear working mechanism of the materials was discussed.By combining the mechanical engineering properties of each test material,an E-B model using the Duncan-Chang model for the surface asphalt milling material and a predictive optimization model using the Duncan-Chang model along with the P-Z shear equation for the crushed stone material and the face-base mixed milling material were established to validated the test results.The results show that all three test material properties changed from brittle to ductile with increasing circumferential pressure,and the crushed stone and face-base mixed milling material specimens displayed strain softening characteristics,while the surface asphalt milling material specimens displayed strain hardening characteristics.The face-base mixed milling material has the potential to replace crushed stone material in the project because the strength values of the two materials are closer(about 5％),whereas the strength differences between the surface asphalt milling material and crushed stone material under various perimeter pressures range from 15％to 21％.Before 2％axial strain,all three test materials show shear shrinkage characteristics,after 2％axial strain,the surface asphalt milling planes still show obvious shear shrinkage characteristics,while the gravel material and the face-base mixed milling planes show shear expansion characteristics,and have the phenomenon of the later shear expansion section decreases.The calculation results of the predictive optimization models can all be in good agreement with the test results,especially the established Duncan-Chang model combined with the predictive model of the P-Z shear expansion equation,which can more accurately reflect the intrinsic relationship between the crushed stone material and the face-base mixed milling material.The research results can provide certain theoretical reference and reference for realizing the reapplication of aging waste materials in road engineering.3 tabs,8 figs,43 refs.
NETL
NSTL
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