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Granular materials are widely used for bases or subbases in pavement structures. They typically exhibit strong anisotropic properties which relate to stress states and particle characteristics. The conventional design procedure for flexible pavements underestimates the anisotropy of resilient moduli. This study established an anisotropic resilient modulus model for granular materials that considered gradation and particle shape characteristics. Vertical and horizontal resilient moduli of certain granular materials were measured in self-developed triaxial tests to obtain corresponding model parameters and anisotropic coefficients. Gradation and particle shape models were established to quantify the granular material characteristics, and the parameters were regressed. Particle shapes were obtained via image processing, and the ratio ( η) of particle sphericity to roundness was chosen as a shape parameter. Results show that η increases with the decrease in particle size, and the average values of η for graded gravel and natural laterite are 0.54 and 0.63, respectively. The η distribution curves indicate that the proportion of relatively anisotropic particles, rather than extremely anisotropic particles, results in the differences in particle shape characteristics. The regression relationship between the anisotropic calculation parameters and the model parameters of vertical resilient modulus, gradation, and particle shape was established. Thus, the horizontal resilient modulus and the anisotropic coefficient can be predicted via conventional resilient modulus tests and gradation, and particle shape analysis. This study shows that the anisotropy of granular materials decreases with the increase in coarse particles and the uniformization of the particle size distribution, and it increases with the increase in anisotropic particles and the polarization of the η distribution.

This paper provides a tree crown reconstruction method. We calculate the total lighted area a leaf receives in a day and analyze the best included angle between a pair of leaves when their mutual overlap is considered. By using discrete summation and equilibrium condition of forces we conclude that when leaf angle is consistent with light angle, the sunlight a pair of leaves receives is the maximum. We make different types of leaf shapes cover the crown to get different coverage, in which the maximum corresponds to the most appropriate shape. This method follows the law of maximum light area in plant growth and once user set the tree crown, the leaf shape can be fixed. Then the whole tree crown is reconstructed. It can be used in tree model reconstruction in broad scene.

Cracks appear in the early cement stabilisation base due to shrinkage. Pavement service life is reduced by the reflecting cracks under load coupled with environment. Geosynthetics can be used as an effective anti-reflective crack material to improve the asphalt concrete performance. Related studies mainly focus on the optimal material type and placement location of geosynthetics. However, the mechanism research of anti-crack propagation is limited and needs further investigation. The methods used to date are hard to reveal the anti-reflective crack mechanism of geosythetics. Therefore, geosynthetic materials cannot be used appropriately. Propagation and resistance characteristics of traffic induced reflective cracks with geotextile placed in the asphalt layer was investigated using extended finite element model. The effects of geotextile placement and tensile modulus were also investigated. Compared with other zones, the geotextile stress over the crack was significantly larger. The geotextile absorbed 15% of the total stress in the asphalt surface layer. The crack propagation stages and final crack length was separate when tensile modulus of geotextile reached 50 MPa. The geotextile with 100 MPa tensile modulus was found to produce the optimal effect on preventing crack. Geotextile placed at a quarter depth of the asphalt layer from the bottom had the best crack resistance.