Advanced Materials Research Vols. 779-780

Abstract: According to the size and connecting characters of soil particles, soil is discomposed into two components as matrix and reinforcement particles respectively with a demarcation size fixed at 0.075mm to investigate the influence of the microstructures on soil strength. Based on the strain gradient theory, a multi-scale matrix-reinforcement particle model was established to study the trans-scale properties of soil strength which indicates that the soil strength is related to the intrinsic length scale, the strain gradient, the matrix properties and the gradation and size of reinforcement particles. A series of consolidated and undrained compression tests of unsaturated remoulded soil were designed to study the trans-scale properties of soil strength. The results showed that: the yield stress of soil increased as the reinforcement particle size decreased, displaying the trans-scale properties of soil strength. The research result is significant to the development of strength theory of soil.

Abstract: Computational fluid dynamics (CFD) numerical simulation is adopted to analyze the drag reduction ability of triangular riblet on tube internal flow. The resistance characteristic of smooth tube and tube covered with triangular riblet surface are compared, and the near wall flow structure over smooth surface and riblet surface are investigated. Based on the simulation analysis, the drag reduction mechanism of riblet surface is studied. Results show that the characteristic dimension of riblet section, i.e., height (h) and width (w) are main factors affecting drag reduction, suggesting that the riblet structure can be optimized according to the actual application condition.

Abstract: Properties, viz. mechanical performances, air permeability, water vapour diffusion, and wicking height of absorbed water in fabrics above level of water, of plain-weave fabrics woven by twistless yarns and equivalent conventional ring spun yarns have been investigated in this paper. The experimental twistless yarns were made by reverse twisting process which spun the yarns on the ring frame and removed the twist of said yarns by reverse twist process. The results show that a fabric produced by yarns which have twists are considerably stronger than the twistless fabric in both breaking strength and tearing strength, air permeability of the twistless fabric is approximately 23.74% lower than its corresponding fabric made by conventional ring spun yarns. However, compared to the fabric made by conventional ring spun yarns, twistless fabric fares well in water vapour diffusion and wickability.

Abstract: A numerical simulation model of laser cladding based on internal powder feeding through a hollow laser beam is set up by the Ansys Parametric Design Language (APDL). Through analyzing this model, the saddle-shaped distribution of energy absorbed in scanning direction is found and the molten pool temperature field of single laser cladding is observed like a comet^[. Base on the single laser cladding experiments, the initial parameters and test plans of laser cladding and the screwy thin-walled part forming are confirmed. The finite element model of laser cladding forming screwy thin-walled part is established. The evolution of temperature field and thermal cycle of the nodes are studied during the screwy thin-walled part forming process. In the emulation laser power is controlled real time according to the analyses above, and the changing value of laser power is obtained to keep the molten pool temperature steady. The screwy thin-walled part is formed successfully based on these data.

Abstract: A new theory is presented to design pressurized conduits, particularly vaulted rectangular conduit. This theory is based on a referential rough conduit model characterized by an arbitrarily assigned relative roughness taken in the fully turbulence flow regime. Thus, the geometric elements of the chosen model are well defined. These allow a direct determination of the required geometric elements of the conduit by the use of a non-dimensional correction factor. A practical example is presented to explain the procedure of calculation. Keywords: Rough Model Method, Pressurized conduit, Vaulted rectangular conduit, Turbulent flow, Discharge, Energy slope.

Abstract: Soil is the most common discontinuous granular material in the geotechnical engineering and its physical and mechanical properties have obvious grain size effect. In view of the insufficient of classical continuum mechanics and existing discrete mechanics, the matrix-reinforcing particles cell element model of soil introduces to account for the grain size effect and microstructure of the soil; then, based on the rotation gradient theory, the elastic-plastic stress-strain relations of soil with grain size factor obtains; finally, using the principle of virtual work establishes the corresponding finite element method.

Abstract: In this work, we will propose some improvements and innovations for Submerged Combustion, namely a Pressurized Submerged Combustion Technology. This paper introduces the Pressurized Submerged Combustion and some basic theoretical research.To understand better gas pressure fluctuations and their influence in flame stability, a mathematical model is developed in this paper, and its particular solution is elucidated. The results show that, the variations of pressure are influenced by bubbling which is a self-excited oscillation phenomenon. Increasing the damping of liquid motion is very helpful for stabilizing pressure fluctuations. The model can be used for guidance and optimization design of Pressurized Submerged Combustion equipments.

Abstract: Based on the airport pavement construction features and utilization requirements, we stabilize the fine-grained soil in Jining district of Shandong province by using the construction-aid (con-aid) soil stabilizer.We test the stress-strain curve and Mohr failure envelope of the triaxial shear of the fine-grained soil before and after being stabilized under various confining pressure by using the unconsolidated-undrained (UU) triaxial test method. We also analyze the change rules of the cohesive force Cu and internal friction angle φu to evaluate the effect of stabilizing fine-grained soil by using the con-aid soil stabilizer. In addition, we discuss the feasibility of applying the stabilizer in constructing the airport pavement and roads.

Abstract: The differential and large settlement may have a great effect on the construction and maintenance of highway. Based on the study of concrete pile composite foundation, the effect of concrete pile composite foundation on reinforcement and influence factors of settlement are analyzed in the paper. The effects of pile modulus and embankment modulus on settlement with numerical simulation method are analyzed in the paper. The result of numerical simulation method is that the settlement of embankment may be reduced with the method of concrete pile composite foundation and pile modulus may have a great effect and embankment modulus may have some effect on the settlement of embankment.

Abstract: Relying on a practical application in pre-stressed concrete box-girder with corrugated steel web, four angle shear connector specimens are made and experimented in push-out test. The results show that: in the ultimate load level, failure model appears after large slip occurring between connector and concrete which shows a good ductility of angle shear connector. The main influence factors for the bearing capacity of connector is thickness of angle web, U-shaped steel provides certain shear resistance ability to same extent. Finally, through the contrast analysis between measured values and theoretical values, a new bearing capacity formula is proposed. Compared with the recommended formulae, the calculated results from proposed formula is most close to the text results, thus new formula can be used for security design and calculation.