Advanced Materials Research Vols. 250-253

Abstract: Based on the retrospect of the catastrophic destroy upon electricity net in the ice disaster which happened in South China 2008 and the power failure in some places of America and Canada in 2003, and upon the analysis of the problems in electricity and gas supply in our country. The authors point out that adopting CCHP (Combined Cooling Heating & Power) system is an important measure which can improve the safety of electricity supply, and presents the scheme of cascade utilization of energy and the running mode in summer and winter. In addition, the paper also analyzes the advantages of the CCHP system to the reliability of electricity supply, and points out that developing CCHP system is mutual-beneficial for electricity power and gas supply.

Abstract: In order to study the changing law of the cold-recycled material between allowable tensile stress and loading number, the relationship between them has been established based on the fatigue equation obtained by fatigue test. The studies indicate that the allowable tensile stress of cold-recycled materials usually decline with the loading number. As for pure cold-recycled material, the decrease of allowable tensile stress is greater than that of added gravel; the cold-recycled material with more gravel content, the decrease of allowable tensile stress is lower than that with less gravel content; the difference of initial allowable tensile stress and initial damage of the material are the main reason for the difference of the change law.

Abstract: Subgrade diseases are exposed more and more serious with raising speed of existing railway in wide range. Fro the complexity of dynamic stress-strain relationship of soil, dynamic triaxial test was used to analyze .the dynamic mechanics behavior under cyclic train load for saturated soft clay in Yangtze Delta region. Compaction coefficient, confining pressure, dynamic shear strsss ratio, inputing stimulus and loading frequence were taken into account in test. The results show that the dynamic stress-strain curves of soil specimen are provided with prominent hysteretic characteristics and area surrounded by hysteretic curves gradually augment and slope of hysteretic curve decreases with the increase of dynamic shear train amplitude. The strong correlation exists between dynamical stress and strain.

Abstract: The authors numerically simulated the natural ventilation in an industrial workshop with heat sources by computational fluid dynamics (CFD) method when the height of air inlet opening was set different values. The flow and temperature fields in the workshop were simulated by realizable k-e turbulent model combined with a Discrete Ordinate (DO) radiation. Results showed the height of air inlet opening strongly influenced the flow and temperature fields in the workshop. When the height of air inlet opening increased, the natural ventilation was improved and more fresh air flowed into the workshop. When the height of air inlet opening increased from 1.7 meters to 3 meters, the temperature in the operation zone of the workshop dropped. When the height of air inlet opening increased from 2.7 meters to 3.7 meters, the temperature in operation zone did not change much, while the temperature in the upper zone of the workshop dropped. The heat distribution factor decreased first with the height of air inlet opening and then increased again. When the height of air inlet opening was 3 meters, the heat distribution factor was minimal.

Abstract: With the rapid urban development of Lhasa in Tibet Autonomous Region, the traditional houses are losing gradually, while a great variety of city housing are springing up all over the city. Spatial patterns of city housing don’t blindly imitate commercial housing in most other cities in china, but have unique characteristics, such as building direction, functional layout, hole set, building construction and so on. The paper selects four types of Lhasa housing, rural traditional dwelling house, low-income apartment, detached house and multi-storey house, to analysis application of passive technology in detail and sums up three developing stages of passive technology in Lhasa area. On the basis, the paper discusses major factors about evolution of passive technology, that they are changes of spatial patterns, structure system and way of energy consumption. In the end, the paper puts forward some suggestions on the passive technology application in new city housing.

Abstract: Deformation analysis of foundation is an important research field in geotechnical engineering, especially analysis on instantaneous deformation and consolidation deformation of saturated soft clay foundations. In this paper, a computation model of instantaneous deformation and consolidation deformation was built on the basis of Biot Consolidation Theory and consideration of mechanism of instantaneous deformation and consolidation deformation and consideration of interrelation of both deformations. A method was proposed to determine initial pore water pressure in soil. Nonlinearity of soil deformation under drainage conditions was considered by combining Duncan-Zhang model with compaction curve of soil, and failure soil elements were processed by Mohr-Coulomb Failure Criteria. By numerical simulation, a nonlinear axi-symmetric FEM program was complied to solve foundation deformation and applied in calculation of soft ground tank settlement. Results show that the method presented in this paper is efficient and suitable to analyze instantaneous deformation and consolidation deformation.

Abstract: The pursuit of life quality is the ultimate goal of the post-modern society. On the basis of the idea of life quality, and through meeting the basic needs of the life space, urban community planning regards the improvement of the life quality in urban community as its ultimate goal. This paper summarizes the core ideas and planning patterns of the current research on the theory of (spatial) quality of life and the relationship between community planning and spatial quality of life both in and abroad, and analyzes the factors that influence life quality in urban community. On this basis the allocation of community space based on the idea of (spatial) quality of life is discussed and relevant principles and processes of community planning are raised.

Abstract: Using the static and dynamic triaxial experimental machine, experimental study of the strength of wet-screened aggregate concrete are carried out under biaxial compression stress ratios, 0.25, 0.5, 0.75 and 1 after 0, 50, 100, 150, 200, 250, 300 cycles of freeze-thaw. The change of surface of wet-screened aggregate concrete specimens after different cycles of freeze-thaw are observed and described. The failure characteristic of specimens and the direction of the cracks are also observed. Based on the test data, the influence of freeze-thaw cycles and compressive stress ratio on the ultimate compressive strength and corresponding stress-strain relationship is analyzed respectively. The relationships between the ultimate compressive strength and freeze-thaw cycles, the stress ratios are given, respectively. On this basis, the unified failure criterion with consideration of the influence of freeze-thaw cycles and stress ratio is proposed. It can serve as a reference for the maintenance, design and the life prediction of ocean structures, hydraulic structures, marine structures and offshore platform in cold regions.

Abstract: Experimental studies were carried out on real rear-axle housing in a farm transport vehicle to investigate the influence of low amplitude preloading on structure life，in order to explore increase potential of rear-axle housing in a farm transport vehicle fatigue life. It is proved that a strengthening area exists in low amplitude loading area. Fatigue lives of rear-axle housings have been increased in some extent with preloading within this area. It can make fatigue life double at most. Based on physical tests, the best strengthening load region of rear-axle housing in a farm transport vehicle was estimated. It provides some technical supports for increasing fatigue life of real rear-axle housing.

Abstract: Composite soils have been widely used in civil engineering applications, especially in slopes, embankment dam and landfills. This paper aims to investigate effect of fiber inclusion on shear stress of composite soil (i.e. clay composite). A series of laboratory direct shear tests carried out to evaluate fiber effect on strength behavior of composite clay. Clay was selected as soil part of the composite and plastic fiber was used as reinforcement. The fiber parameters differed from one test to another, as fiber length were changed from 20 mm to 65 mm and fiber content were varied from 0.7% and 2%.Normal stress kept constant at 150 kpa. For each test, stress_ displacement graph derived and the results were compared. The results proved that inclusion of fiber affected shear stress behaviour of clay composite so that increasing in fiber content and length caused increasing in shear stress.