Abstract
Graded crushed stone (GCS), as a cheap and essential component, is of great importance in road construction. The irregularity and variability of particle shape is known to affect the packing characteristics of GCS, such as compactness and void ratio. In this study, the realistic particle outline is first automatically extracted based on digital image processing and deep learning algorithms. Then, the elongation (EI), roundness (Rd), and roughness (Rg) of GCS are quantified by shape evaluation algorithms. Moreover, based on the establishment of the GCS shape library, the gravity deposition with various elongations is simulated using the discrete element method to study the packing features of GCS. The elongation effects on the macroscopic and microscopic quantities are explored. Finally, the shear behavior of GCS is studied. The results illustrate that elongation has a significant effect on the packing of GCS.
Highlights
With the development of the highway industry and the deepening of engineering practice, the asphalt pavement structure used in China has been diversified from the single semirigid asphalt base, and the graded crushed stone flexible base asphalt pavement has become one of the main pavement structure forms in China
The particle outlines are firstly extracted based on deep learning algorithms. e U-NET model is trained for contour extraction. en, the shape evaluation indexes including elongation, roundness, and roughness are quantified
Graded crushed stone (GCS) is of great significance in road construction as an essential material used in the base or transition layer. e packing properties like compactness and void ratio can be affected by the irregularity and variability of particle shape
Summary
With the development of the highway industry and the deepening of engineering practice, the asphalt pavement structure used in China has been diversified from the single semirigid asphalt base, and the graded crushed stone flexible base asphalt pavement has become one of the main pavement structure forms in China. As a basic road material, the shape of crushed stone particles has a significant effect on its mechanical properties. Numerical simulation methods are often used in exploring the properties of GCS. Ren et al [11] proposed a random calculation model for GCS and studied the Direct Shear Tests (DST) of GCS by PFC2D. Jiang et al [13] established a numerical model of dynamic triaxial test of GCS based on PFC2D and founded that the size of the specimen has a slight influence on the simulated value of axial strain when specimen height is greater than 40 cm and diameter is greater than 20 cm. This study lays a foundation for future research about GCS
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