Applied Mechanics and Materials Vols. 405-408

Abstract: Established the Car Line - Bridge coupling dynamic model, then entered the actual parameters of train, track and bridge structural, obtained the dynamic excitation at the rail bridge pier bottom when the train passes. On this basis, established the pier - soil - building coupling dynamic model by combining finite element method and infinite boundary element method, analysed the vibration characteristics of soil and buildings surrounding the elevated rail way, brought an in-depth study to the effects of elevated rail transit train running on the environment. The results show that: 1)The the environmental vibration induced by elevated rail transit is low-frequency vibration, the vertical ground boils down to low-frequency vibration of 10 - 25Hz, the transverse vibration of housing column is fundamental frequency vibration near 10Hz, the vertical floor boils down to low-frequency vibration of 10 - 25Hz. 2) The vertical ground vibration response level decreases with the increase of distance to the rail centerline when the train passes. 3) With the increase of vibration wave propagation distance, components of higher frequency decay more quickly.

Abstract: The road surface plant disease detection is an important content of highway maintenance work, is also a key in the process of highway construction and maintenance management, basic technology. According to index of road surface detection classification discusses the testing method and technology of asphalt pavement, and the road surface detection technology is introduced, meanwhile discusses the trend of the development of detecting technology.

Abstract: As elastic modulus of unbounded granular materials is strongly influenced by stress level, pavement structure parameters must be taken into account in its modulus determination. It is found that the backcalculated modulus of granular base vary according to the layer on which FWD is tested, which verifies the fact that unbounded granular materials is strongly influenced by stress level. And an earth pressure cell that is applied to acquire compressive stress conducting to granular base course when the pavement is subjected to vehicle load is buried on the top of granular base course. The backcalculated modulus is then applied to analyze mechanical response of the pavement by 3D finite element method. At last, the calculated result is compared to the dynamic response acquired in-situ by earth pressure cell.

Abstract: This article proposes a new type of cracking resistant water-proof pavement structure by building mechanical model and performing lab tests. This cracking resistant water-proof layer is a composite material formed by using high performance emulsified asphalt that makes two or more kinds of crushed stone with different particle size interlocking and binding with each other. In addition to this, this article preliminary determinates three field testing indexes, which are asphalt distribution measurement, pullout strength test and shear strength test of modified emulsified asphalt. At last, it is proved that the cracking resistant water-proof layer have a favorable effect on the experimental road.

Abstract: This study aims to predict the Dynamic Load Coefficient (DLC) of tyre forces from truck axles. Dynamic Load Coefficient is frequently used to characterise the dynamic loads generated by axles. It is a simple measurement of the dynamic variation magnitude of the axle load, for a specific combination of road roughness and speed. Under normal operating conditions, the DLCs value is typically in the range of 0.05-0.3, and close to zero when the trucks wheels are moving over a perfectly smooth road. To achieve the objectives of this study, which is to determine the DLCs value for seven different types of axles, a simple validated quarter-truck model was excited by a random road surface profile, in order to simulate a vehicle-road interaction. Points are equally spaced along the simulated road to generate dynamic loadings over a broad range of truck speeds. Multiple trucks gross-weight conditions were used to present realistic traffic behaviour. The results showed that irregular road profiles, exciting the vehicle as it travelled, caused continually changing tyre forces. Also, dynamic loading was seen to be fundamentally influenced by the type of suspension (i.e., air and steel), loading condition, and vehicle speed. For example, the DLC value of the tyre forces of the quarter-truck fitted with a steel suspension was found to be more than twice that of the truck fitted with an air suspension. Tyre forces of the one-third laden truck were more aggressive than any other loading condition, due to the uncertain body-bounce generated by the truck, which was strongly dependent on surface irregularities. At low speed, the DLC was greatly decreased if the load was increased. Furthermore, DLC value was always lower for trucks with air suspension over steel suspension, for the same load and vehicle speed. However, air suspension efficiency was clearly better for higher axle loads.

Abstract: Asphalt mixing plant cold recycled materials as the layer below has been widely applied in recent years, It has better performance compared with other structural materials for the prevention and treatment of reflective cracking,for further analysis the stress conditions of the material as a grass-roots-bit suffered upper load transfer.In this paper, useing the ABAQUS software modeling analysis of three different structural pavement layers on top and bottom of the situation by force. The results show that the grassroots cold recycling layer structure has obvious characteristics of flexible it has better controlable to reflective cracking.

Abstract: Previous research revealed that influence function is strongly influenced the appropriateness of pavement damage prediction and are demanding to be concern in order for better prediction of long term pavement performance. In order to identify the impact of traffic loading condition on the influence function of the pavement toward failure, further stucdy was done to determine the exponential value in the Damage Equivalent Law for varies loading condition and also vehicle speeds. To achieve the aims, the simple quarter truck model was efficiently used with personal computers to predict pavement loading. Towards reality of traffic loading condition will contain a distribution of axles load between unladen and fully laden, the study was further taking into account realistic axle load variation. Results are presented from a study to evaluate the relative influence of truck speed and axle load variation on the stiffness of the asphaltic layer and thus the primary response of the pavement. In conclusion, the exponential value in the Equivalent Damage Law is clearly sensitive to both factor.

Abstract: Since many influencing factors on the bending property of asphalt mixture, in order to explore the various factors on the influence degree of bending property, 16 kinds beam specimens of asphalt mixture, formed by different asphalt binders and different gradations of aggregate, were tested. Then the mechanics parameter such as the bending strength and failure strain were calculated. The influence degree of eight factors on the bending properties was analyzed by the gray entropy method. The result show that asphalt Brookfield viscosity exert significant influence on the maximum bending strain, filler-bitumen ratio and the maximum particle size exert significant influence on the bending strength.

Abstract: In order to study the effect of tourmaline on asphalt mixture design indexes, the optimal asphalt content of modified asphalt mixture with different contents of tourmaline were determined through Marshall Test, and the variation of optimal asphalt content caused by tourmaline was analyzed. The effect of tourmaline on density, porosity, VMA, VFA, stability, flow value were studied. Under the guidance of surface theory and mortar theory respectively, the Marshall Volume indicators of tourmaline modified asphalt mixture were analyzed comparatively. A mix design method for asphalt mixture modified inorganic powder is recommended.

Abstract: In order to study the influence of bearing on the anti-seismic property of medium-small span bridge, based on a continuous beam bridge 5×30 m , the dynamic effects of four kinds of system was analyzed with static analysis and nonlinear time history analysis. The study shows that PTFE slide rubber bearings set at the abutment and laminated rubber bearings set at the piers was the best combinations for seismic.