Applied Mechanics and Materials Vols. 256-259

Abstract: Abstract: Fatigue cracking is a main form of structural damage of asphalt pavements. In general, there are four approaches to characterize the fatigue behavior of asphalt concrete. The methods including Phenomenological Approach, damage–energy fatigue approach, fatigue fracture mechanics and fatigue damage mechanics. Based on continuum damage mechanics, fatigue cycles of structural members in test can be greatly reduced and a unified approach of predicting fatigue crack initiation and fatigue crack propagation can be constructed. Generally, one damage variable is defined to account for the relative decrease of Young’s modulus with loading and, therefore, the change of Poisson ratio can not be considered. To accurately describe the coupling relationship between damage and stress fields, a bi-variable damage model to describe the variations of shear modulus and bulk modulus is the direction of future research.

Abstract: In order to treat the collapse problem of red sandstone slope on Hunan Liu-Li Highway, laboratory experiments of its lithology were conducted, and the main parameters of red sandstone were acquired, including its basic physical properties, its disintegration characteristics, and its mineral compositions. By collecting research information of red sandstone slope, the main features and reasons of the slopes collapse were concluded. In comparison to the original and other treatments, the conclusion that the flexible protective technology is suitable for red sandstone slopes was reached.

Abstract: When the crack appears in semi-rigid base layer, the stress mode of pavement structure transits from infinite continuum to limited size board, and the crack tips become stress concentration areas. This paper establishes the three-dimensional eight nodes entity reduced integral unit model by the practical tire contact pressure and contact area, to calculate and analyse the influence on the mechanical indexes in pavement structure with or without crack in base layer from high modulus asphalt layer under half-sinusoid load. Analysis shows that enhancing the modulus of surface layer could effectively reduce the tensile stress in bottom of base layer and avoid the bending broken in base bottom, but there exists risk that the bottom subbase and asphalt layer cracking.

Abstract: In order to provide a effective pavement analyze and decision making platform for the highway engineers, a pavement maintenance decision support system with Web-GIS integrated is implemented in the system. In this work, format of the data is predefined as a specification of the system. All the data are organized according to their relationship. Google map service is used as Web-GIS platform. The system is implemented according to JavaEE framework. The components of the system are implemented as java classes. Pavement performance evaluation, prediction and maintenance strategy decision are implemented as corresponding services. They are integrated as a system. According to the results, the system is effective and reliable.

Abstract: Aim at the difficulty of disaster early warning of rock fall of highway in mountain areas, a new idea, sound and light integrated disaster early warning technique for moving vehicles in mountain areas, was proposed. A new type of traffic sign was designed which can receive the monitoring data of dangerous rocks of road slope and make early warning in the way of sound and light when the rock fall is going to occur or is occurring, the structure and function of the new traffic sign was developed, and technical requirements and installation problems were also discussed.

Abstract: The originating base of large shield is a fundamental guarantee of shield machine prosperous assembly and originating posture. This paper based on Nanjing Weisan Road Tunnel Across Yangtze River, the requirements of large TBM assembly and the guarantee measures on originating posture is introduced.

Abstract: Ice layer on pavement surface was a serious problem for highway traffic safety. Crumbed rubber asphalt mixture was an effective way to drive ice layer away from surface. Through wheel test asphalt mixture specimen with ice layer at negtive temperature, the paper studied ice breaking performance of asphalt mixtures containing different amount crumbed rubber. Pendulumlike friction test BPN after wheel test was taken as an performance index of crumber rubber asphalt breaking ice. Results shown that the quantity of crumbed rubber and the performance of ice breaking had good linear relationship and more rubber content had better slide resistance recover speed at same wheel arround number.Through numerial model of pavement covered ice based on FEM method, the paper had analyzed the relationship between elastic modulus of crumbed rubber pavement and ice stress-strain on pavement, and put forward the mechanism of ice breaking.

Abstract: This paper described the working principle of dynamic compaction and the main points of construction, Using degree of compaction and deflection, evaluating construction quality based on actual project. we can solve the problem of construction quality of the road bed effectively and the waste of the dust, thus avoiding the environment pollution of waste dust and make a good economic and social profit.

Abstract: The dynamic compacted stone piers in reinforcement of soft foundation road are introduced in this paper. The design proposal of dynamic compaction on stone piers, and the construction quality test method are proposed. The settlement detection curve is obtained, finally some suggestions are given. The monitoring results indicate that: the sedimentation velocity is from big to small, and then tends to stop gradually, which is in line with the general rules. It is found that the work of monitoring and tracking detection of road soft foundation after construction until the settlement tends to stop is rare to be seen in domestic. Therefore, the results can give meaningful guidance for the real practice.

Abstract: Combined with the reconstruction of the existing railway line with speed of 200km/h, a calculation model of bridge-subgrade transition section was developed by the theory of vehicle-track-bridge/subgrade coupling dynamics. The simulation program was compiled, which could be used to calculate and evaluate the dynamic characteristics of transition section in speed-up line. The results of field reconnaissance operations and calculations show that the track structure stiffness in transition section is uneven, or even part of the function fails, which can not meet the requirements of speed-raising. Some measures, such as transition section database establishment, class-based management implementation, separate design and separate reinforcement adoption, can be used for the transition sections, which are listed as the objects of emphatic assessment. In addition, the evaluation system will provide theoretical support and references for design and construction in reconstruction project of transition section.