Study On The Influence Of Sub-grade Soil Modulus On The Early Damage Of Pavement

The sub-grade is the foundation of pavement structure, and it directly affects the performance and stability of the whole pavement structure. The large deformation of sub-grade soil has become one of the main cause of pavement disease, which may be generated by the insufficient modulus and bearing capacity of sub-grade soil. Researchers have been paid more attention to the influence of sub-grade soil modulus on the pavement early damage.So a new idea to study the stress complexity of pavement structure is needed.Based on the Mohr-Coulomb criterion and Drucker-Prager criterion, Asphalt Pavement Potential Damage Indexes(APPDI2D and APPDI3D) are defined under the condition of two-dimensional and three-dimensional stress states in this paper. In order to guide the integration design and reduce the structural damage of sub-grade and pavement structure, and improve the performance and service life of pavement structure, using the road surface deflection value, the tensile stress at the bottom of asphalt layer and the compression strain at the top of sub-grade, the new evaluation index, the the study has been developed on stress distribution and early damage of pavement structure from the angle of the resilient modulus of sub-grade.As results, the following studies are carried out in this dissertation:Firstly, based on the strength theory of rock and soil mechanics, the evaluation indexes of pavement performance were defined and explained under the condition of two dimensional and three dimensional stress states.Secondly, with the aid of existing test results at home and abroad, the relationship between strength parameters and elastic modulus of the material was discussed without considering of the particle size gradation and asphalt type.Thirdly, according to Prof. Kim’s calculation model and results, the mechanics analysis of different pavement structures were carried out under different modulus of sub-grade soil. Therelationship between the different indexes and sub-grade soil modulus was studied, and the early damage modes and the principle stress components of the pavement were discussed under different sub-grade soil modulus.Finally, an integrated design system for sub-grade and pavement structure and material was developed with the MATLAB programming software according to the analysis results and the finite element theory.The research methods and conclusions of this paper have a certain theoretical significance on integrated design of structural and material for sub-grade and pavement structure, which can provide reference for the following study.