Applied Mechanics and Materials Vols. 99-100

Abstract: Density should impact sustainable transportation but its exact role is still under discussion due to various interpretations and inconsistencies in the literature. To explore its impact on urban recreational travel in large Chinese cities under rapid urbanization, this paper took Shanghai as a case, studied its spatial patterns of both population density and road density, surveyed 11 popular urban parks on user access modes and analyzed the mode changes in spatial terms. The passive effect of low-density urban sprawl on sustainable recreational travel in large Chinese cities was addressed.

Abstract: The two-dimensional unsteady heat transfer models of common roof, insulation roof and phase change roof were established, and the thermal characteristics of common roof, insulation roof and phase change roof with different phase transition temperature were analyzed based on CFD software, the hourly average temperature distribution of their top and bottom surface from initial stage to steady stage and 24-hour hourly average temperature distribution of and average heat flux of bottom surface in steady stage were also attained. The results show that, under air conditioning constant temperature mode, addition of insulation material and phase change material observably improve the heat insulation performance of roof structures, the cooling and energy saving effect of roof more obviously, the attenuation multiple and delay time of roof more obviously, and make the hourly distribution of average temperature and average heat flux of roof bottom surface much gentler. In addition, choosing a phase change material with suitable phase transition temperature according to outside air comprehensive temperature is the key to utilize its latent heat more effectively.

Abstract: In order to discuss the action mechanism of polyvinyl alcohol (PVA) polymers in high performance cement-based composites(HPCBC), the effect of PVA on the strength of HPCBC with different ratio of polymer to binding material (P/B) was studied,and action mechanism of PVA polymers in HPCBC were also studied by SEM and X ray diffraction(XRD). Results show that the strength of HPCBC with addition of PVA polymers can be improved greatly,and there exists an optimal P/B with which the strength were upmost; In this experiment, the optimal P/B is 2.5%,and at this point the strength attain extremity with compressive strength and flexural strength of 113.6MPa, 23.0MPa respectively.By using SEM and XRD, it is found that the interface zone structure is improved and so it was of high-density, low-porosity and high adhere-strength, and PVA polymers chemical action works in the course of cement hydration and hardening.

Abstract: Combined with the Engineering environment and the requirements of construction of the deep foundation of metro station of South Gate in Xi'an, and in accordance with the basic methods and the basic principles of the monitoring of the construction of deep foundation, it gives a monitoring program of the deformation of the deep foundation pit and researches on in-site monitoring for the deformation of deep foundation, to ensure the safety of metro station construction. At the same time, it focuses on an analysis of the horizontal deformation of the retaining piles and the axial force of steel support, to provide a reference for the similar engineering information construction in the future.

Abstract: Gas permeability mechanism for the laminated salt rock gas storage is very complex. The key problem is to establish the permeability model and to propose the corresponding numerical method suitable for salt rock with weak interlayer based on seepage theory in porous media. An efficient and accurate method is proposed to model the flow in fracture and matrix. The fractures are regarded as boundaries among adjacent matrix blocks. Darcy’s law governs velocities in the matrix blocks, while the flow in the fracture on boundaries is set up by accounting for the fracture’s thickness. This model can reflect the fracture flow which is different from the equivalent medium model, and its computational complexity is less than that of double porous model. Combining with the field situation of Jintan gas storage in China, the pressure distributions of storage with different cyclic pressures for gas injection and production in five years are studied. It is concluded that the effect of permeability on gas pressure distribution is very important.

Abstract: The analysis for occupational stress of source has gathered great importance in recent year. Using traditional factor analysis to divide different preference was difficult. The data from questionnaire was vagueness and uncertainty. After using fuzzy factor analysis, the result of data can find new 12 factors in 61 attributes. There have more explanation to contain attributes then traditional factor analysis. Thus, fuzzy factor analysis can render classification of occupational stress indicator reasonable and acceptable than if the traditional method.

Abstract: Microorganism is an unique living element and has the ability to precipitate minerals through the process of biomineralisation. The precipitation process occured naturally and most of the precipitated products are very important compound composed of such as carbon, nitrogen, oxygen, sulphur, phosphorus and silica. So far, concrete incorporated with microorganism that able to precipitate calcium carbonate (calcite) was reported. However, little information on silica precipitation and its effect on concrete properties has been revealed. In this present study, the concrete specimens were incorporated with Bacillus subtilis silica adsorbed in their cell wall. Concrete specimens with five different concentration of Bacillus subtilis cell which are 104, 105, 106 and 107 cell/ml and control (without Bacillus subtilis) were cast. The experimental investigation aims to prove that the silica precipitated by this microorganism can enhance the concrete properties namely its compressive strength and resistance to carbonation. The microstructure of the concrete contained Bacillus subtilis was also examined. It appears that the inclusion of Bacillus subtilis into the concrete enhanced the compressive strength. The concentration of 106 cell/ml was found to be the optimum concentration to give most enhanced effect to the compressive strength. However the effect of including Bacillus subtilis to the resistance to carbonation of the concrete specimen is found to be insignificant.

Abstract: The main purpose of this paper is to analyze the stability and safety problems of braced excavation enclosure, surrounding strata and side slope during construction of Shangshuijing station in Shenzhen Metro Line 5. The paper presents stability discrimination of the braced excavation and side slope by discussing their force and deformation regularity using Flac3D, and puts forward some project proposals about its design and construction. The results show that: (1) The stability coefficient of braced excavation enclosure becomes smaller because of biasing impact of side slope, but this project can meet the stability requirements, (2) The biasing impact of side slope has little influence on deformation of surrounding strata starting on the other side of braced excavation without slope, and (3) To ensure construction safety under condition of side slope, the braced excavation should be excavated starting from the zone far from the side slope, steel pipe can be used as assistant reinforcement at the corner of side slope if necessary.

Abstract: This paper researches the green six hole brick with crushing autoclaved aerated concrete block and fly ash as the main raw material, and researches its strength, shrinkage and frost resistance in natural maintenance condition and wet maintenance condition by experiment. Research results show that the six hole brick not only keeping environmental health, saving energy and recycling, but also its performance meet the relevant requirements, so it deserves popularization and application.

Abstract: As a powerful 3D design software, 3DS MAX are usually used only as a manual drawing and modeling tool, not many designers use MaxScript modeling or to design animations. The article introduced the technique to implement the procedures, and proved the efficiency of this technique by applying it to two real-world structure engineering projects, in the area of Hydraulic Structure Engineering and Suspension Bridge Structure Engineering.