The skeleton structure composed of mineral aggregates is the main body to bear and transfer external loading in asphalt mixtures. To investigate the loading transfer mechanism of the mineral aggregate skeleton, the uniaxial penetration test and Discrete Element Method (DEM) were conducted for the Mineral Aggregate Mixture (MAM) to analyze its mechanical behavior. The three-dimensional strong force chain (SFC) was identified and evaluated based on the proposed recognition criterion and evaluation indices. The results indicate that 4.75 mm should be the boundary to distinguish the coarse and fine aggregates. The skeleton composed of aggregates located on SFCs has better bearing and transferring loading capacity due to its SFC number, average length, and total length decreasing with an increase in the aggregate size. Compared to SMA-16 and OGFC-16, AC-16 exhibits a higher number and total length of its SFC, a smaller average length of its SFC, and a lower average strength of its SFC. Consequently, AC-16 has a lower bearing and transferring loading capacity than that of SMA-16 and OGFC-16. In addition, approximately 90% of SFCs can only transfer external loading downward through 3–5 aggregates. The average direction angle of the SFC formed by fine aggregates is significantly higher than those formed by coarse aggregates. This indicates that the load transfer range of MAM composed of fine aggregates is noticeably larger, leading to lower loading transfer efficiency.
The stress waves generated by tunnel blasting in urban rock layers can affect the safety of adjacent buried structures in the overlying geological layers. To ensure the safety of buried structures, it is crucial to understand the blasting vibration characteristics in the geological layers. In this paper, the analytical solution for the vibration velocity response in geological layer subjected to P-wave is derived. Based on a specific tunnel blasting excavation project, the influence of incident wave frequency, layer thickness, and incidence angle on the vibration velocity distribution along the depth direction are investigated. Results show that the vibration velocity in the upper soil layer does not strictly attenuate with increasing distance from the blasting source but rather exhibits a fluctuating trend. As the frequency of the incident wave increases, the normalized vibration velocity on the ground surface exhibits a periodic decreasing trend, and the distance between the initial fluctuation point and the ground surface decreases. The normalized vibration velocity in the soil layer does not exhibit a monotonic decrease as the soil thickness increases. With an increase in the incident angle, a general declining pattern is observed in the normalized vibration velocity along the depth direction.
The condition of mechanical equipment during machining is closely related to the accuracy and roughness of the workpiece. In an intelligent sensing environment, a large amount of multi-source data reflecting status information are generated during processing, and a number of studies have been conducted for machining equipment reliability analysis. In this paper, the reliability analysis method of machining equipment based on condition monitoring technology is taken as the main line. And an up-to-date comprehensive survey of multi-source information during the cutting process, failure physical analysis for signal selection and reliability assessment based on condition information will be provided. Finally, the future challenges and trends will also be presented. It is a feasible and valuable research direction to evaluate the reliability of machining equipment for product quality characteristics.
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