Applied Mechanics and Materials Vols. 97-98

Abstract: Against the status quo of Yu-Chang freeway traffic accidents occur frequently, through the investigation of traffic accidents, Summarized characteristics of typical traffic accidents of Yu-Chang Freeway, analyzed the causes of traffic accidents from the four major factors of people, vehicles, roads and environment, provided some treatment strategies which can solve the status of the frequent occurrence of traffic accidents, and which will protect the this highway of harmony ,safe and smooth.

Abstract: According to bond condition was simulated by contact unit and pavement parameters, such as temperature, load, and structural condition were given, a three-dimensional finite element model was established to analyze the temperature-load coupling stress for asphalt overlay. Effects of parameters for asphalt overlay, old cement concrete plate, joint and foundational response modulus on its temperature-load stress. Results show that the temperature-load stress of asphalt overlay is great influenced by asphalt overlay’s E1 and thickness h1, the thickness of the cement concrete slab h2, foundational response modulus k and the joint width δ. But the length L and width B of cement concrete slab, and the joint load transfer stiffness C has little effect on it. The temperature-load stress of overlay can be reduced by increasing the thickness of asphalt surface.

Abstract: Seriously inhomogeneous track rigidity of turnout will strengthen the dynamic response of wheel/rail system and shorten its service life. Combined with complicated structure characteristics of turnout, the simulation calculation model of track rigidity had been established. Main factors which influence the track rigidity were considered, such as the rail changing section, sharing baseplate, the foundation under rail. Distribution regularity of track rigidity in turnout had been obtained. The calculation result showed that track rigidity of turnout was seriously inhomogeneous. The maximum track rigidity was 162.2kN/mm in point rail of stock line, and the minimum track rigidity was 69.5kN/mm in stock rail of switch line.

Abstract: The damage of void under cement concrete slab is one of the main diseases in cement concrete pavement. By finite element method, a 3-D model of cement concrete pavement structure was established to simulate the partial void under the cement concrete pavement slab with different loading conditions. The process of the division between the subgrade and the slab with a soft area under the slab are reappeared. The changing rules of the void size with the number of cycle load in case of different tie pressure and loading location (at the center, edge or corner of the slab).

Abstract: Expressway is developed quickly in China, but its construction is seriously affected by the un-uniform deformation of the subgrade. The basic concepts of post- treatment and pre- treatment on freeway subgrade are firstly discussed in this article, and then a conclusion that Post- treatment Method can obviously reduce the after-work sink is gained, which may be used as a practical reference for lighting the un-uniform deformation of thick-filled subgrade in soft-soil area.

Abstract: Large amounts of deicing agents (abbr. Deicer) were applied on road pavements for snow and ice control each year in the cold region. The traditional deicers used on pavements resulted in metallic corrosion of vehicle and serious adverse environmental impacts. By contrast, acetates and formates were more environmentally friendly and more effective. After application of new deicers, heavy binder bleeding and severe stripping problems were observed occurring together with loss of asphalt pavement stability in northen Europe and northen America. Recently the large quantities of acetate-based deicers applied each year in China, damage by the deicers similar to that observed in those wereas would also occur in China. To shed light on neglected distress by deicer and guide the best practices of deicer application, asphalt mix design and maintenance of asphalt pavement, the paper revealed the asphalt mixture performance variation corroded by deicers and corrosion mechanism using immersion tension test, aqueous solutiion test and immersion penetration test.

Abstract: To resolve heavy-duty trucks side over the boxes, scraping the guardrail and other accidents when driving into the entrance of emergency escape ramp, according to studying on lateral stability of the out-of-control heavy-duty trucks and combining with their mechanical properties, this dissertation analyses the wheelpath’s geometric features when the out-of-control heavy-duty trucks rush into the emergency escape ramp from the main road, results a reasonable range to adapt the efflux angle of emergency escape ramp on our mountain expressways, and provides necessary theoretical references for the selection of the efflux angle on mountain roads.

Abstract: Ballast flying problems obsess the high speed railway developments, causing damages to the train and deteriorations to the rail. In the paper, DEM is used to conduct ballast flying mechanism microscopic study, results show ballast flying increases with train dynamic force, and decreases with ballast size and friction coefficient, ballast flying counteracting measures are presented, such as ballast bed parameter and ballast glue. In the end, future possible microscopic ballast flying model method is presented by DEM coupled with CFD.

Abstract: Vehicle load is one of the most important factors influencing service performance and service life of pavement. In the pavement design and analysis, different axle loads need be conversed to the standard axle load based on the equivalent deterioration principle of pavement. Pavement surface deflection values under different axle loads have been measured on several expressways in this paper. The correlation relationships between deflection and axle loads are analyzed. The regularity of deflection and axle conversion index based on deflection equivalent are analyzed, too. The axle conversion formula based on deflection equivalent for asphalt pavement is regressed according to the actually measured deflection data. This research achievement can provide us with a reliable axle load conversion method for asphalt pavement design.

Abstract: Abstract. Through the experimental analysis on performance of the water permeability and conservation and the shear resistance of graded gravel base, the influencing factors and changing rules, as well as the internal relations of the drainage ability and structural performance are found out; the key factor for balancing the contradiction lies in the scope and content of the fine aggregates of graded gravel. Provided that other constraint conditions are met during the gradation design, good water permeability and conservation performance of graded gravel permeable base shall be guaranteed as long as the content of the fine aggregates of graded gravel could be controlled within a reasonable scope, meanwhile, the mechanical stability could also be ensured. The paper provides the method for determining the content scope of fine aggregates of graded gravel, and references for the design of graded gravel permeable base of the porous pavement.