scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Mechanical Response of Asphalt Surfaces under Moving Traffic Loads Using 3D Discrete Element Method

01 Jun 2022-Journal of transportation engineering-Vol. 148, Iss: 2
TL;DR: In this paper , the authors investigated the mechanical response of asphalt surfaces under moving traffic loads using the three-dimensional (3D) discrete element method (DEM) and established a discrete element model for asphalt surface based on the random generation algorithm of irregular particles.
Abstract: This paper investigates the mechanical response of asphalt surfaces under moving traffic loads using the three-dimensional (3D) discrete element method (DEM). As an example of a semirigid base asphalt pavement, a discrete element model for asphalt surface was established based on the random generation algorithm of irregular particles in Python language and DEM. The model considered the temperature gradient and fatigue damage to simulate the permanent deformations, shear stresses, and strains in asphalt surfaces under different working conditions (e.g., different temperatures and numbers of repeated loads). Part of the simulation results was verified by performing a full-scale accelerated loading test (ALT). Results show that the 3D discrete element model embedded with temperature gradient and fatigue damage could be used to predict the mechanical response of asphalt surfaces under repeated loads. As the temperature increased, the mechanical response of asphalt surfaces increased. The middle surface was the main area of shear stresses in semirigid base asphalt pavements. Due to fatigue damage, the stresses and strains in asphalt surfaces increased with the number of repeated loads.
Citations
More filters
Journal ArticleDOI
TL;DR: In this paper , a three-dimensional meso-structure discrete element model of asphalt pavement was generated with the FISH programming language and its mesomechanical response under vehicle load was analyzed.
Abstract: Numerical simulation is an effective way to study the mechanical response of asphalt pavement, which is very important for the pavement structural design. In this study, a three-dimensional meso-structure discrete element model of asphalt pavement was generated with the FISH programming language and its meso-mechanical response under vehicle load was analyzed. The contact forces within the asphalt pavement, in asphalt mastic, in coarse aggregates and between asphalt mastic and coarse aggregates were studied. The results of the study show that the contact forces within the asphalt mixture are highly uneven. The number of contact points in coarse aggregates account only for about 10% of all contact points while the sum of the contact forces in coarse aggregates contributes to over 50% of all contact forces. This demonstrates that the coarse aggregates bear most of the vehicle load. The average normal contact force in coarse aggregates is about 5 N and the average tangential contact force in coarse aggregates is about 2 N. The modeling results provide a quantitative understanding of the distribution of loading in asphalt pavement.

1 citations

Journal ArticleDOI
TL;DR: Based on thermal-mechanical coupling simulation analysis and physical engineering tracking observation, the mechanical behavior and response of a continuously reinforced concrete and asphalt concrete composite pavement layer were analyzed, and the causes of cracking on the surface and bottom of the asphalt layer were revealed as discussed by the authors .
Abstract: Based on thermal–mechanical coupling simulation analysis and physical engineering tracking observation, the mechanical behavior and response of a continuously reinforced concrete and asphalt concrete (CRC + AC) composite pavement layer were analyzed, and the causes of cracking on the surface and bottom of the asphalt layer were revealed. Studies have shown that under normal driving conditions, the AC layer, which is usually in the position of the wheel load gap and wheel load side, more easily generates a longitudinal “corresponding crack”. Compared to normal driving, longitudinal cracks are generated more easily inside of the curve, and transverse cracks occur more easily on poor stadia curves. When the AC layer thickness is less than 8 cm, the AC layer is more prone to bottom-up cracking, and it is more prone to top-down cracking when it is more than 8 cm thick. Comprehensively considering the tensile stress, shear stress, and the thickness of the AC layer, it is recommended that the suitable thickness range of the AC layer is 8 cm~14 cm. The calculated results show good agreement with the physical engineering investigation. The research results can provide a theoretical and scientific basis for cracking control and the rational design of a CRC + AC composite pavement layer.

1 citations

Journal ArticleDOI
TL;DR: In this article , the authors analyzed the dynamic responses of asphalt pavement in dry and saturated conditions under full-scale accelerated loading and found that the increase in vehicle load significantly increased the magnitudes of stress, strain, and pore water pressure.
Abstract: Asphalt pavement presents diverse dynamic responses to vehicle loading in dry and saturated conditions, which can be systematically explored by numerical simulation. Building a numerical model based on the actual conditions of asphalt pavement is necessary, and relevant field tests should be subsequently conducted to monitor dynamic responses to calibrate and validate the numerical model. On the basis of strictly controlling the paths of vehicle wheels during field tests, this study numerically analyzed the dynamic responses of asphalt pavement in dry and saturated conditions under full-scale accelerated loading. The trends of the modeling results were consistent with those of field measurements. The increase in vehicle load significantly increased the magnitudes of stress, strain, and pore water pressure, while vehicle speed showed an obvious impact on pore water pressure. The dynamic responses decreased with pavement depths. Water made the dynamic responses more complex, and pore water pressure significantly decreased with depth within the upper layer of saturated asphalt pavement. Transverse distributions of indicators presented obvious compressive states in the regions in direct contact with vehicle wheels, while tensile states were found in the range of the middle vehicle axle. The numerical results provided a basis for field measurements in future studies, especially for the exploration of factors of temperature and layer depth.

1 citations

Journal ArticleDOI
TL;DR: In this paper , the authors used 3D discrete element models to predict the mechanical response of crumb rubber-modified (CRM) asphalt pavements under traffic loads using three-dimensional (3D) discrete element method (DEM).
Abstract: This study aims to predict the mechanical response of crumb rubber-modified (CRM) asphalt pavements under traffic loads using three-dimensional (3D) discrete element method (DEM). First, irregular-shaped aggregates were generated in Python language, and discrete element models of six different asphalt layers, which considered the temperature gradient and fatigue damage, were established using 3D DEM. Then, model parameters were obtained through the uniaxial creep test for asphalt mastics at different temperatures. The fatigue damage was implemented by introducing a damage factor into the Burgers model. Finally, three mechanical response parameters (namely, permanent deformation, shear stress and transverse strain) of the six asphalt layers under traffic loads were analysed and compared. Results show that the mechanical response of CRM asphalt layers under traffic loads is significantly influenced by number of repeated loads, temperature, and asphalt layer materials. The shear stress and transverse strain at the wheel centre vary along the depth of asphalt layers, and the middle layer is the principal area of shear stresses in asphalt pavements.

1 citations

References
More filters
Journal ArticleDOI
TL;DR: In this article, a heterogeneous fracture model based on the discrete element method (DEM) is developed to investigate various fracture toughening mechanisms of asphalt materials using a high-resolution image processing technique.

183 citations

Journal Article
TL;DR: ABAQUS, a three-dimensional, dynamic finite element program (3D-DFEM), was used to analyze flexible pavements subjected to moving loads at various speeds as mentioned in this paper.
Abstract: Predominantly flexible pavement structural response to loads is predicted by using an elastic multilayer analysis. This type of analysis is based on the assumption that pavements are subjected to static loads and that paving and subgrade materials are linear elastic materials. In this paper, ABAQUS, a three-dimensional, dynamic finite element program (3D-DFEM), was used to analyze flexible pavements subjected to moving loads at various speeds. A number of material models were used to represent actual material characteristics such as viscoelasticity and elastoplasticity. The validity and then the application of 3D-DFEM to flexible pavement analysis were examined. Validation was accomplished by analysis of both static and dynamic cases. The static and dynamic verification studies indicated that 3D-DFEM can be used with confidence to predict actual pavement response from moving loads.

163 citations

Journal ArticleDOI
TL;DR: In this paper, a 3D microstructure-based discrete element model of asphalt mixtures was developed to study the dynamic modulus from the stress-strain response under compressive loads.
Abstract: The main aim of this paper is to develop three-dimensional (3-D) microstructure-based discrete element models of asphalt mixtures to study the dynamic modulus from the stress-strain response under compressive loads. The 3-D microstructure of the asphalt mixture was obtained from a number of two-dimensional (2-D) images. In the 2-D discrete element model, the aggregate and mastic were simulated with the captured aggregate and mastic images. The 3-D models were reconstructed with a number of 2-D models. This stress-strain response of the 3-D model was computed under the loading cycles. The stress-strain response was used to predict the asphalt mixture's stiffness (modulus) by using the aggregate and mastic stiffness. The moduli of the 3-D models were compared with the experimental measurements. It was found that the 3-D discrete element models were able to predict the mixture moduli across a range of temperatures and loading frequencies. The 3-D model prediction was found to be better than that of the 2-D model. In addition, the effects of different air void percentages and aggregate moduli to the mixture moduli were investigated and discussed.

139 citations

Journal ArticleDOI
TL;DR: In this article, a 3D finite element (FE) model was developed to investigate the dynamic responses of thin, flexible pavement under impulsive loading similar to a falling weight deflectometer test.
Abstract: A three-dimensional (3-D) finite element (FE) model was developed to investigate the dynamic responses of thin, flexible pavement under impulsive loading similar to a falling weight deflectometer test. The FE model simulated the hot-mix asphalt (HMA) surface layer as a linear viscoelastic material and considered the cross-anisotropic stress dependent modulus for the unbound base layer. Implicit dynamic analysis was used to consider the effect of inertia on pavement structural responses. Using two thinpavement structures of different HMA layer thicknesses, 76 and 127 mm, the study analyzed the effects of cross-anisotropic stress-dependent aggregate base modulus and dynamic analysis on pavement responses, including surface deflection, tensile strain at the bottom of the HMA layer, deviator stress in the base layer, and compressive strain on top of the subgrade. Results showed that use of the cross-anisotropic stress-dependent modulus for the unbound base layer resulted in greater predicted pavement response...

111 citations

Journal ArticleDOI
TL;DR: In this article, the authors used the discrete element method (DEM) to simulate the dynamic mechanical behavior of asphalt mastics, defined as dispersions of aggregate fillers within a medium of asphalt binder.
Abstract: This study uses the discrete element method (DEM) to simulate the dynamic mechanical behaviour of asphalt mastics. Asphalt mastics are defined as dispersions of aggregate fillers within a medium of asphalt binder. The fillers refer to the fraction of mineral aggregate passing the 200-mesh sieve, (i.e. smaller than 75 μm). Mastic measurements obtained using the dynamic shear rheometer were compared to DEM predictions and available micromechanics-based models. Three asphalt binders (ABD-1, AAM-1 and ABM-1) and four mineral fillers (glacial gravel, granite, limestone and greywacke) were used to prepare the mastics in this study. The stiffening effect of the mineral fillers was investigated at different filler volume fractions. The DEM results captured the stiffening behaviour of asphalt mastics as a function of the volumetric concentration of mineral fillers. The DEM results exhibited a high rate of stiffening that is typically observed in experimental measurements of mastics at relatively low volume concent...

109 citations