A case study on a large geotextile mat cofferdam combined with steel sheet piles was conducted using field testing andnumerical simulation to optimize the design and assess its performance. The failure mechanism and ...
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A case study on a large geotextile mat cofferdam combined with steel sheet piles was conducted using field testing andnumerical simulation to optimize the design and assess its performance. The failure mechanism and overall stability were investigated by numerical simulation, considering potential influence factors, including pile length, width ratio (W2/W1), water level, and excavation depth. The width ratio was identified as a critical influencing factor. Specifically, an optimized ratio of W2/W1=0.6 demonstrated the best overall performance. When the steel sheet pile intersects the potential failure surface, the stability improvement is most significant, particularly with a length of 15 m in the current case. Field tests were employed to examine the performance of the optimized cofferdam design. Water level fluctuations, surface displacements, and both horizontal and vertical displacements at various depths were monitored to assess the cofferdam's behavior. Results from both numerical simulations and field monitoring conclusively affirm the cofferdam's capability to meet stringent safety criterion during the construction and operational phases. This work fills gaps in standardization of large geotextile mat cofferdam design by providing guidance on geometric configuration, reinforcement integration, and soft soil risk management, thereby advancing engineering practices for similar projects.
This paper presents a study of dynamic responses of underground structures based on "World Expo" underground structure in Shanghai. analysis is performed using the open source finite element framework OpenSe...
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ISBN:
(纸本)9781315228914;9781138626331
This paper presents a study of dynamic responses of underground structures based on "World Expo" underground structure in Shanghai. analysis is performed using the open source finite element framework OpenSees. A typical section of four-storey thirteen-span "World Expo" underground structure is adopted to analyse by using dynamic time-history analysis. 2d Opensees numericalanalysis model is performed to compare displacement and acceleration of each soil layer. Shear force, moment of structure components, such as side walls, beams, columns and slabs, are analyzed to obtain the seismic response pattern of the structure. FEA (finite element analysis) model with super-structure and FEA model without super-structure are built to compare different responses during seismic response.
It is difficult to clarify the characteristics of flood flows in a total river system because of insufficient data for the upper river basin. numericalanalysis is an effective tool for complementing flood observation...
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It is difficult to clarify the characteristics of flood flows in a total river system because of insufficient data for the upper river basin. numericalanalysis is an effective tool for complementing flood observation data in space and time. The objective of this study is to develop an unsteady 2d numerical analysis method for a river with tributary inflows in the upper river basin. The inflow boundary conditions of sharp discharge hydrographs from tributaries were estimated using water level hydrographs obtained from observation stations in the main stream;these stations were installed far downstream from the confluence points. This paper demonstrates that the method could be used to investigate the propagation and transformation of the discharge hydrographs from the main and tributary streams by using the sparse water level hydrographs observed in the main stream. The installation method for the water level observation stations is also discussed.
A lot of research on the 2d or 3d effects of large-scale basins (within several kilometers depth) have been conducted in the past. However, different 2d aspects of small-scale sedimentary basins (within tens of meters...
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A lot of research on the 2d or 3d effects of large-scale basins (within several kilometers depth) have been conducted in the past. However, different 2d aspects of small-scale sedimentary basins (within tens of meters depth) remain in the developing stage. Here, an attempt is made to analyze different aspects of small-scale basins using both numerical and empirical investigations. In the first step, the 2d effects of small-scale basins on strong motion characteristics are numerically examined both in the time and frequency domains. In addition, the effects of input motion are also explained by the results of model excitation in different orthogonal directions. Then, the numerical outcomes are verified by the analysis of actual earthquake data recorded at a downhole array in the Fujisawa small basin, Japan. In the second step, since available recorded earthquake data in small basins with a clear understanding of subsurface geology are very limited, different 2d aspects of the small basin are parametrically investigated. For this purpose, extensive parametrical studies are carried out on the main features of a small basin such as slope angle, shape, infill soil properties, and basin thickness by using the finite difference numerical method. The horizontal and vertical peak ground accelerations of 2d with respect to 1d ones are defined as the horizontal and vertical aggravation factors (AG(H) and AG(V)). The AG(H) and AG(V) factors show large sensitivity to infill soil properties, shape and thickness, and small sensitivity to slope angle. The values of AG(H) and AG(V) factors vary in the range of 0.5-2 with large variations around small basin edges due to wave coupling, conversion, scattering and focusing in the vicinity of small basin edges. These cause a complicated pattern of 2dde-amplification and amplification, which mostly affect the motion in the high frequency range (>1 Hz). Finally, the outcomes provide numerical and field evidence on the 2d effects of small
The authors have performed a 2d numerical analysis of the electrical characteristics of polysilicon thin-film transistors (TFTs). made by excimer laser crystallisation (ELC), with high field-effect mobility (> 300c...
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The authors have performed a 2d numerical analysis of the electrical characteristics of polysilicon thin-film transistors (TFTs). made by excimer laser crystallisation (ELC), with high field-effect mobility (> 300cm(2)/Vs) and low threshold voltage (< 1.5V). In spite of the highly non-uniform defect distribution in ELC-polysilicon (mainly localised at the grain boundaries), the authors show that the device characteristics can be adequately described by using, in the numericalanalysis. an effective density of states uniformly distributed within the semiconductor. This model, already verified in solid phase crystallised polysilicon TFTs. allows the analysis of ELC-polysilicon devices to be simplified.
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