Applied Mechanics and Materials Vols. 90-93

Abstract: According as three motion modes of motion process of the seated large diameter cylinder breakwater(LDCB) under random waves , the dynamic model system composed of spring-damper-antislider to control the lateral sliding is introduced, and corresponding dynamic analysis space model is established. The space model is realized by Parameter Design Language APDL of the large finite element software ANSYS. Calculated results by the space model comparing with those by the plane model respectively , some valuable conclusions are achieved. The validity of the model, which can be used in dynamic response analysis of the seated LDCB under random waves, is confirmed by the given example.

Abstract: This paper presents the definition of the estuarine turbidity maximum, its formation reasons and the factors of variety. According to this information, the Yangtze River estuarine turbidity maximum is analyzed as the typical estuarine turbidity maximum. The results show that North Channel turbidity maximum is different with the others for different hydrodynamics. The Delft3D model is applied to simulation the phenomena and the results are agreed with the analysis.

Abstract: Using the CFX software and the Large Eddy Simulaion (LES) method, this paper numerically simulates the hydrodynamic characteristics of the flow around a 3d circular cylinder at high Reynolds number (Re=5.6×10³, 2.8×10⁴, 1.1×10⁵). The numerical simulation focuses on investigating the vortex shedding angle, the characteristics of the vortex shedding and the vortex tube, the base pressure, the static and the fluctuating drag and lift. The result of calculation shows that the forces of every section along the span of cylinder are symmetrical with respect to the middle section. Moreover the flow around the cylinder obviously appears three dimensional characteristics at high Reynolds number.

Abstract: The increasing importance of the sustainability challenge in o engineering has led to the development of free surface ocean structure of various configurations. In this study, the hydrodynamic characteristics of a perforated free surface, semicircular breakwater (SCB) are investigated for irregular wave conditions under the different water depths. The performance of the breakwaters was evaluated in the form of coefficients of transmission (CT), reflection (CR) and energy dissipation (CL). The measured wave modification in front of the structure and in the structure’s chamber were quantified and presented in the form of a ratio relative to the incident wave height, respectively, which are then presented as a function of the relative immersion depth (D/d) and the relative structure width (B/Lp), where D = the depth of immersion, d = the water depth, B = the structure width and Lp = the wavelength corresponding to the peak wave period. The measured wave modification in front of the structure and in the breakwater’s chamber were quantified and presented in the form of a ratio relative to the incident wave height, respectively. It is found that the wave attenuation ability of the SCB model improves with the increase of D/d and B/Lp. The SCB performs better as an energy dissipater than as a wave reflector.

Abstract: Abstract. In this study, process of wave-induced silty seabed response was explored in a rectangle flume. Based on the experimental phenomena, the variations of pore water pressure and theory analysis, discussions were made on the mechanism of wave-induced silty seabed instability. Results indicated that seabed under wave nodes would experience fluidization and oscillation under wave actions, obvious pore pressure accumulation was observed at the same time. The mode of wave-induced silty seabed instability was fluidization. The mechanism of wave-induced silty seabed fluidization was a combination of excess pore water pressure and shear failure, the chief factor of fluidization could be ascribed to wave-induced cycling shear stress. The steady state strength was somewhat an expression of the level of wave-induced decrease of soil strenth that could finally reach, therefore, it could be used for the estimation of wave-induced fluidization of silty seabed.

Abstract: Chloride ion ingression into concrete under flexural load is investigated in the paper. Concrete specimens have been stored in 3.5%NaCl solution or 3.5%NaCl + 5%Na2SO4 solution for 210 days. The effect of flexural load and sulfate ion to chloride ion transmission is studied. The experimental results show that sulfate ion reduces chloride ion transmission in concrete. But when concrete under flexural load, Sulfate ion has plus and minus effect on chloride ion ingression into concrete. When the flexural load rate is low, sulfate ion reduces chloride ion transmission. But the flexural load is high, the negative effect of sulfate corrosion plays a main role. When concrete exposed to 3.5%NaCl+5%Na₂SO₄ solution, chloride ion diffusion coefficient of concrete in tensile zone increases with flexural load. And in compressive zone, the chloride diffusion coefficient decreases first and then raises with increasing flexural load.

Abstract: The sixth Chongqing metro line is taked for example, numerical simulation is applied for finite analysis and calculation, the safety of the primary support and the second lining are calculated respectively in different level of surrounding rock, double hole case,different bedrock and overlying abandon ballastless thickness for 45 cases,and then based on the result analysis and calculate the rational buried deepth of the surrounding rock under the different level, And according to the actual measurement of deformation calculation value and deformation value of hole is used for comparison, reference and basis for the similar case is presented.

Abstract: Deformation monitoring is typically undertaken using spare, point-wise geodetic surveying techniques, such as total station or GPS. Deformation monitoring using terrestrial laser scanning is gaining considerable attention mainly due to the high spatial resolution of the acquired data. It can provide dense 3D information of the surface of an object. A disadvantage of the technique may be the difficulty to assess some fixed benchmarks on the surface of the deforming area, unless they are special targets that can be recognised by the accompanying software. To solve this problem, a new automatic deformation acquisition method based on nurbs surface was presented. The paper discusses methods of nurbs surface modelling implemented for deformation monitoring and approaches used to measure the deformation from surfaces. Finally, applications involving the use of laser scanning in bridge are presented.

Abstract: INPHO is foreign professional digital photogrammetry software, including aerial triangulation encryption, digital terrain model matching, the digital orthophoto rectification and image mosaic series modules. This paper, taking DMC image as a case study, according to production practice, states the method of making Digital Orthophoto Map (DOM) using all relevant modules of INPHO, and further points out several notes in the process of making DOM. Practice shows that making DOM using INPHO series software and paying attention to the mentioned precautions can speed up production rate, improve production efficiency, while its mode of operation is also greatly simplified compared with the normal mode of operation. It is a good way of making DOM.

Abstract: The outlier identification and correction of the geomagnetic parameter measurement is an important influencing factor for the probability and precision of the matching algorithms. The ream-time measurements of the geomagnetic field parameter can be considered as the first-order non-stationary random process, the real-time measurement value can be predicted by using the multi-level recursive method, the outlier identification can be done by the Dixon criterion, and the correction can be made by using the median filter and the one step prediction value. The inspection is carried out by using the emulation data and actual data, the results show that not only the isolated type but also the spot-type outlier value can be detected well and the signal reconstruction error is less than 5%.