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Chen F.-Q.,Fuzhou University | Su F.,Fuzhou University | Su F.,Huadong Engineering Corporation | Shi Y.-Z.,Huaqiao University
Jisuan Lixue Xuebao/Chinese Journal of Computational Mechanics | Year: 2014

Problems of karst collapse may often occur in railway and highway construction. How to evaluate the influence of existed karst on adjacent tunnels reasonably is meaningful to design of tunnel engineering in karst regions. Considering a simplified cave as ellipse shape section and tunnel as circular, a simplified analysis solution for stresses and deformation characteristic of tunnel due to the influence of adjacent ellipse karst cave is proposed in the paper. Schwarz's alternating method was used to derive the formulas for calculating the stress and displacement of the surrounding rocks. Since the depth is larger than the size of the tunnel, the effect of gravity gradient is ignored, and gravity loads are simplified as uniform normal loads along far-field boundary. Comparison between the results from the closed solutions and those from numerical analysis by two-dimensional finite element method indicates that the closed solution is reliable and applicable for the stress and displacement field around circular tunnels adjacent to the influence of an ellipse karst cave at great depth.

Ren N.,Dalian University of Technology | Li W.,Huadong Engineering Corporation | Li Y.,Dalian University of Technology
Taiyangneng Xuebao/Acta Energiae Solaris Sinica | Year: 2016

The aerodynamic characteristics of offshore wind turbine blades during typhoon were investigated according to the observation data of typhoon "Damrey" (2005, NO.0518) and the main design parameters of National Renewable Energy Lab (NREL) 5 MW wind turbine. Firstly, because the full observation data of typhoon was a long duration process with obvious variation characters of wind speed and wind direction, so one 3-hour representative truncated typhoon wind speed-wind direction time history was selected. Secondly, considering the main airfoil design parameters of 5 MW wind turbine blades and the variable-speed and collective-pitch control system, the aerodynamic characteristics of offshore wind turbine blades during representative typhoon period were studied based on Blade Element Momentum (BEM) theory, and the numerical results was compared with the results of simplified method. The important effect of the time lag of the variable-speed and collective-pitch control system on the blades aerodynamic loads during typhoon was revealed. Finally, the blade aerodynamic loads during typhoon for stopped wind turbine were further studied, and the active blade parked strategy for typhoon event was suggested to reduce the blades aerodynamic loads and ensure the safety of the key structures of wind turbine. © 2016, Science Press. All right reserved.

Zhou H.,Shanghai JiaoTong University | Zhou H.,Huadong Engineering Corporation | Wan D.-C.,Shanghai JiaoTong University
Shuidonglixue Yanjiu yu Jinzhan/Chinese Journal of Hydrodynamics Ser. A | Year: 2014

The numerical simulation of the unsteady flow around wind turbines with different blades numbers are conducted with the Arbitrary Mesh Interface Method based on the free source OpenFOAM software. The turbulence model k-ω SST and unstructured grid are chosen to analyze the difference between aerodynamics of two blades and three blades wind turbine under different wind conditions. Detailed numerical results of vortex structure, thrust, torque and pressure distribution of different wind turbine were presented. These results are important to the finite element analysis and the design and research of wind turbines with different blades numbers.

Li H.-K.,Nanchang University | Li H.-K.,Tianjin University | Deng B.-M.,Nanchang University | Wei B.-W.,Nanchang University | And 2 more authors.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2016

The mean square deviation of the dynamic displacement of an arch dam during the flood discharge period is an important indicator for evaluating the intensity of vibration. It is difficult to reflect the distribution characteristics of a whole vibration response field accurately if relying directly on the limited points measurement in dynamic test and also it is not comprehensive and concrete to evaluate the dam vibration safety only with the data measured at limited points. So it is of great significance to inverse the whole dynamic displacement field of the arch dam based on the dynamic response measurement at limited measuring points. Taking the Ertan high arch dam as an engineering example, the dam vibration test under flood discharge excitation was carried out. In accordance with the dynamic displacement responses at limited measuring points arranged on the prototype arch dam, the whole dam dynamic displacement field was inversed by using the genetic algorithm and finite element modal analysis. The specific flow chart of the inversion was provided. The inversion results show that the whole dam dynamic displacement field can be obtained through the dynamic displacement response measurement at only seven measuring points arranged on the top arch of the dam. Simultaneously, the inversion results and the measured values are in good agreement. The method provides a new technique for the reasonable safety assessment of high arch dam during the flood discharge period. © 2016, Chinese Vibration Engineering Society. All right reserved.

Li H.-K.,Nanchang University | Liu S.-L.,Nanchang University | Wei B.-W.,Nanchang University | Huang J.-L.,China Institute of Water Resources and Hydropower Research | Fu X.,Huadong Engineering Corporation
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2015

The vibration signal frequency components and noise levels in multi-sensor measurement of a flood discharge structure vary with the measurement positions. These signals can be fused to a vibration signal accurately and comprehensively reflecting the vibration characteristics of the overall structure with the multi-information fusion technology. Here, aiming at traditional data fusion algorithms fixing the convergence factor and requiring higher similarity of signals, a dynamic response data fusion algorithm based on variance dedication rate was proposed. Fusion coefficient at different instants in this algorithm changed with the relative importance of the signal information. The weighting factor was dynamically allocated based on the variance dedication rate to realize the dynamic fusion of mulati-point vibration signals. The numerical signal simulation and the original measurement of the flood discharge structure dynamic response data fusion results showed that the dynamic data fusion method proposed here can excavate weak signals hidden in noise and the fused signal can reflect the vibration characteristics of the overall structure more accurately and comprehensively. The comparison between this method and the traditional cross-correlation fusion algorithm showed that this method can effectively highlight the dominant frequency components of signals, retain the structural natural frequency components in the original signals and has a stronger applicability. ©, 2015, Chinese Vibration Engineering Society. All right reserved.

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