Applied Mechanics and Materials Vols. 405-408

Abstract: The interlayer bonding of double-layer porous asphalt pavement will show more variations with different construction technologies, such as one-step molding by double-layer (hot on hot) paver, or paving layer by layer (hot on cold) with or without tack coat, and the variations will definitely have influences on pavement structure. Different interlayer technologies are studied in this paper on three levels including simulation experiments on specimen by indoor preparation, calculation of pavement mechanics, and construction of testing road, so that optimal interlayer bonding technology for double-layer porous asphalt pavement is discussed in combination with its effect on permeability.

Abstract: Coarse-grained soil is widely used in subgrade engineering, creep property of which is the important factor that affects long-term settlement of fill embankment. The creep property of sandy slate coarse-grained soil under different moisture conditions is analyzed through uniaxial compression creep test on influence rule of moisture content on creep of coarse-grained soil. Relations between moisture contents and creep parameters are studied on the basis of H-K Creep Model. It turns out that moisture content is the important factor that affects creep property of sandy slate coarse-grained soil and using dry or saturated coarse-grained soil is able to decrease long-term settlement of embankment.

Abstract: Most of current construction project management software focus on text, quantity information and lack of engineering graphics, display, query and analysis of features and other spatial features. In order to solve these problems, GIS is taken as the core, Multipatch programming is used in the natural ground and roadbed, drawing 2D features are stretched for 3D visualization and dynamic 3D display of construction progress. The TIN model is constructed and the main spatial analysis functions are implemented, including the query of 3D point information, the query of longitudinal section, cross section, volume, surface area as so on at any position. A road engineering construction management system is developed in Microsoft Visual Studio2010 platform using c # 4.0 language, the GIS secondary development tools ArcGIS Engine9.3 and Microsoft Access2007 database. GIS is taken as the core in basic framework of the system, the system has a certain application prospect in the road construction management.

Abstract: The purpose of this paper is to study dynamic-characteristics of asphalt-pavement on semi-rigid base loaded with moving, heavy-load. Based on transient-dynamics theory, three-dimensional finite-element (FE) model was developed for structural dynamic-responses analysis using ANSYS software. The heavy-duty axle-load model was established according to Belgium-Design Code, and the dynamic-load was simplified as sinusoidal-wave load. For the pavement mechanics indexes (road-surface deflection, the vertical and lateral stress, the shear stress and the strain), the time-history curves and distribution conditions in the structure were presented. Expect tensile-strain at surface-layer, the relationship between axle-load weight and mechanic-indexes are almost linearly proportional. The calculation shows that under moving heavy-load, the surface-layer suffers from rather high vertical compressive-stress and shear-stress, the base and subbase are loaded with high tensile-stress and the subgrade top undergoes large vertical-strain . For asphalt-pavement on semi-rigid loaded with moving, heavy-load, besides the conventional indexes (including road-surface deflection and tensile-stress at the bottom of base or subbase), the design indexes should also include the shear-stress on road surface, the vertical-strain on the top of subgrade and the vertical compressive-stress on road surface.

Abstract: Six kinds of TOR rubber asphalts with 5%-30% rubber powder contents of were selected to carry out conventional high-temperature tests and dynamic shear rheological tests to obtain some parameters reflecting the high-temperature performance of asphalt binders, such as softening point, dynamic viscosity at 60°C, rutting factor (G^*/sinδ) at 60°C and critical temperature of rutting factor (T_G*/sinδ). The results show that the changing tendency of two rheological parameters of TOR rubber asphalts, G^*/sinδ at 60°C and T_G*/sinδ, is ascend in first and descend at last with the increase of rubber powder content proportion. The high-temperature performance of TOR rubber asphalt with the rubber powder content about 20% is the best. Softening point and dynamic viscosity at 60°C, as two conventional high-temperature parameters of asphalt binders, can describe the high-temperature performance of TOR rubber asphalt with the rubber powder content below 20%, but cannot evaluate accurately the high-temperature performance of TOR rubber asphalt with the rubber powder content above 20%, because TOR rubber asphalt has formed a network structure at this moment.

Abstract: Traffic load is important parameter used in the analysis of the new pavement design. However, few studies have done extensive and intensive research on the load stress for asphalt pavement of porous concrete base. Because of that, it is necessary to study the stress of porous concrete base in the asphalt pavement based on traffic load. In the paper, first of all, threedimension finite element model of the asphalt pavement is created for the aim of doing mechanical analysis for the asphalt pavement. And then, the two main objectives of this study are investigated. One is calculation for load stress of porous concrete base, and the other is analysis for load stress of porous concrete base. The results show that load stress of porous concrete base decreases, decrease and increase with increase of bases thickness, surfaces thickness and ratio of bases modulus to foundations modulus respectively.

Abstract: In this paper, the electrical analysis of emulsified asphalt and aggregate explains the reaction mechanism of the emulsified asphalt and aggregate. When emulsified asphalt and wet mineral aggregate contact each other, asphalt particles with a charge have chemical adsorption with aggregate at the surface of mineral aggregate, and asphalt particles are arranged on the surface of later quickly. Subsequently, asphalt of recycled mixture can be more cohesive after a series of process between emulsion and aggregate, such as demulsification and drying by distillation. A compact structure is formed by asphalt wrapping aggregate to make recycled mixture high strength. The mole - coulomb theory analyzes formation principle of emulsified asphalt cold recycled mixture strength. The strength of the recycled mixture mainly depends on the cohesion and internal friction among materials. In early stages, asphalt can not bonding because of water, which reduce the friction resistance of recycled mixture, and lead to the early strength of recycled mixture is small. After curing, the recycled mixture has the similar structure like hot asphalt mixture, which the cohesion and frictional resistance of recycled mixture became strong and the strength increased greatly. Besides, this paper expounds the dual role of cement that hydration reaction and of being active mineral powder in the process of emulsified asphalt cold recycled mixture strength formation.

Abstract: The concept of spiral line development (SLD) is introduced at first in this paper, then the design idea of SLD is discussed, and the characteristics and patterns of SLP are summarized. According to the terrain adaptability and linear continuity requirements of SLP, rationality of the SLD applied in the high-grade highways in mountain areas are analyzed from the aspects of technology, safety, economy and environmental protection. The results show that SLD is a better decision in the case of the limitation of topographic and geological conditions, too large height difference between the two control points, no natural line development conditions, and the reverse loop development dissatisfying the requirements of high-grade highways index

Abstract: A Line Segments Identification model is put forward to realize the existing railway horizontal alignment reconstruction. Firstly, Hough transform based on constraint adjustment quantity is introduced to reject the abnormal points that will affect the quality of the identification in latter steps. Then total least square method is used to get the linear segments, after which the circular curve segments and the transition curves segments will be got. At last, an evaluation function which has four arguments: circular curve radius , two transition curves length and length of straight line between curves was built and its function value is the sum of squares of all distances from measuring points to reconstruction alignment, based on the function , optimal alignment will be solved out by Powell method. Example shows that the reconstruction result is considerably superior to the traditional method and is feasible for the engineering practice.

Abstract: The double-layer pavement design with a combination of normal concrete layer and porous concrete overlay is the promising way towards tunnel pavement. This paper is aimed to confirm the optimal construction opportunity of porous concrete overlay based on the mechanical behavior of tunnel pavement. Parameters like compressive strength, shearing strength and tensile splitting strength were examined in laboratory and field experiment respectively. It is observed that the strength of the pavement gradually decreases with the increase of the construction time interval between the two layers. The results have revealed that the reasonable construction opportunity of porous concrete overlay should be controlled between the initial setting time and the final setting time of normal concrete layer.