Advanced Materials Research Vols. 368-373

Abstract: AC-20 is a widely used in Expressway Close-Graded asphalt mixtures. Based on fractal theory, the fractal dimension range is defined by Marshall Test result analysis of gradation fractal dimension and the Marshall Test parameters. According to the gradation curve of fractal dimension and the degree of fitting, selection of Target Proportioning Design of asphalt mixture, gradation design, optimization test method for reducing test volume has certain guiding role.

Abstract: Moisture damage is one of the main forms of early failure in the asphalt pavement. Setting porous concrete permeable base can release water from the road structure. The common construction technology for porous concrete is traditional vibration compaction, which is helpful for the strength formation of the base, but unhelpful for the stability and smoothness of the base.In this sdudy, Compaction-free Porous Concrete (CPC) permeable base was proposed, which can not only satisfies the strength requirement of structures, but also guarantees the stability and the smoothness of the base. The idea of volume method was adopted on mix design of CPC. Mix proportion parameters such as aggregate dosage, cement dosage and water dosage were calculated and confirmed based on experimental study. The performance test results show that CPC designed by this method can satisfy the design standard. Accordingly, the design method of CPC is feasible.

Abstract: Thermal stresses at the extreme temperature conditions can cause various pavement distresses. These distresses may degrade the structural performance of bridge deck pavements (BDP), such as, upheaval, low-temperature cracking, reflective cracking, etc. It is essential to understand the influence of the extreme temperatures on the pavement distresses. Based on the analytical solutions of temperature in BDP, the simplified formulae for calculation of stresses for the extreme temperatures (maximum and minimum temperatures) in BDPs were developed in this study.The calculated results obtained from the developed simplified formulae were then compared with the data measured in the field. The differences between them were found to be within 2°C.

Abstract: Based on large amount of meteorological wind field records observed in Wenzhou district, this paper analyzed the annual maximum wind speed (maximum 10 minute mean wind speed), annual extreme wind speed (maximum 3 seconds mean wind speed), reference wind pressure and wind field characteristics of typhoon in Wenzhou. The results shows that the annual maximum wind speed have a decreased trend on the whole in different areas of Wenzhou, and the trend in coastal area is more obvious than that in inland areas; the annual maximum wind speed in different areas of Wenzhou is unsteady and the typhoons have great effect on it; the value of reference wind pressure in Dongtou is greater than the value given by the design load code of China (GB50009-2001, 2002), but the values of other areas are less than the value of Code. Based on the wind field of three typhoon records, some significant results about the variation and routine characteristics of typhoon are also discussed.

Abstract: To study the experimental method of axial compressive test of concrete columns in service strengthened with bonding FRP(fiber reinforced plastic), the post-tensioned pre-stressing method was employed to exert initial stress to the specimens before bonding FRP, Then FRP was bonded. Axial loading method of the specimens was that one main jack exerted axial force and two jacks provided stiffness for the specimens. In this way the complete stress-strain curves of specimens was obtained. The results indicated the technical target of axial compressive test of in service concrete columns strengthened with FRP was greatly achieved by using this experimental method.

Abstract: Pressure-impulse diagrams have been extensively used for damage assessments of structural components subject to a specified blast loading. In this paper, a numerical method is used to generate pressure-impulse diagrams for unreinforced masonry walls subjected to blast loading. A previously developed plastic damage material model accounting for strain rate effects is used for brick and mortar. Three levels of damage criteria are defined based on maximum deflection of the wall and rotation of the supports. The obtained blast response for unreinforced masonry walls are validated against field test data. It is shown that the obtained pressure-impulse diagrams have an improved ability to evaluate the damage level of masonry walls.

Abstract: With the fast development of scientific technology and city economy construction, Mining method adopted for shallow underground works, have being applied in the construction of underground passages at present. With typical Wenzhou underground passages embedded in silt and built by shallow mining excavation as the project background,3-D stress and deformation characteristics of a passage in the city center was analyzed by means of Finite Difference software FLAC3D, compared with field monitoring data of the underground street passage near the Second Affiliated Hospital of Wenzhou Medical College. Much important engineering information was obtained, such as the displacement deformation and stress nephogram of the passage, which can be referred for the construction of the similar underground projects in soft soil areas in future to make the projects more reasonable, safe and economical.

Abstract: With the development of subway in major cities, the density of underground railway tunnel increases. At the same time, the form and the area of subway tunnel become different. All these make higher requirements for stability of wall rock. The super section shallow multi-arch tunnel between Hananzhan Station and Nongkeyuan Station of Harbin subway ,with the twin-side heading tunnel construction method do harm to the wall rock for many times. It becomes more difficult for below the main road. This paper, using finite element analysis ANSYS software to simulate the excavation process, obtains rock settlement of the four-arch tunnel through on-site monitoring data, and further validates the feasibility of the twin-side heading tunnel construction method.

Abstract: With the maturity of construction technique of traditional concrete materials, self-compacting concrete (SCC) is reflecting its superiority to traditional materials in construction technique, engineering adaptability, mechanical property, durability, energy conservation, environmental protection, etc. The analysis on the space construction and manufacturing process of the Science Centre in Wolfsburg, Germany reveals that the application of SCC in large public space has made remarkable achievement with the combination of art and technology, and enjoys broad prospect of development.

Abstract: The characteristics of tunnel fire are analyzed, and the numerical simulation of some tunnel of Shenyang railway is made with the CFD software star-ccm+ 5.02, which applies the field modeling method. A comprehensive understanding of tunnel fire characteristics and flue gas development are obtained, through analyzing the concentration field and temperature field, which may provide the theoretical background for evacuation design in tunnel fire. The effective measures of fire rescue and evacuation are also put forward.