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Changsha, China

Tang B.B.,Central South University | Liu B.C.,Central South University | Deng Z.H.,Wuling Power Corporation
Applied Mechanics and Materials

This paper takes cascade hydropower station project as the research object. It puts forward an economic post project evaluation of hydropower station's analysis framework -- "Static analysis and comprehensive evaluation" based on building the evaluation index set and data envelopment analysis. This paper takes economic post project evaluation of Yuanshui cascade hydropower station as an example to verify the science and effectiveness of the analysis framework and model. The results enrich the theory and model technique of economic post project evaluation of hydropower stations. © (2013) Trans Tech Publications, Switzerland. Source

Li G.,Central South University | Li G.,Key Laboratory of Precise Engineering Surveying & Deformation Disaster Monitoring of Hunan Province | Dai W.,Central South University | Dai W.,Key Laboratory of Precise Engineering Surveying & Deformation Disaster Monitoring of Hunan Province | And 3 more authors.
Wuhan Daxue Xuebao (Xinxi Kexue Ban)/Geomatics and Information Science of Wuhan University

Models and methods of analysis for deformation monitoring are always set for the time series data of one monitoring point. An auto-regressive model can be used for modeling dam deformation to forecast the displacement. In the traditional method, it is necessary to establish the auto-regressive model for every monitoring point. To some extent, the traditional method has to model different models for every monitoring point on the dam which make us do the same thing many times. However, as a whole structure, monitoring points on a dam are related to each other. The traditional time auto-regressive model does not consider the relationship between different monitoring points on the dam. To consider the spatial correlation between measuring points and thereby establish a unified model, a space- time auto-regressive method is used to model the displacements of the Wuqiangxi dam. Space-time auto-regression is just used once for all the monitoring points on the dam which save time of processing space-time series. By analyzing and forecasting the horizontal displacements of the dam, our test results show that a space- time auto-regressive model can be used for fitting and forecasting displacement series both in the temporal and spatial domains. Source

Zhang G.-J.,Changsha University of Science and Technology | Zeng L.-X.,Changsha University of Science and Technology | Chen A.-Z.,HydroChina Zhongnan Engineering Co. | Yang S.-L.,Wuling Power Corporation | Peng C.-L.,Hongyu Engineering
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering

For the impervious construction in soft stratum, there are various technical problems, such as easy collapse of boreholes, vertical lift induced by difficultly pressed grouting, large waste led by easy grouting leakage, and difficult grouting control. The traditional methods of "sleeve valve pipe grouting", "embedded screen pipe tube" and "orifice closed grouting" are difficult to meet the design requirements in deep soft ground. To reduce cost and to improve efficiency, a new construction method, high pulsating pressure grouting from below with stemming slurry materials, is put forward, and one of the key techniques, slurry sealing technique, is described. For the construction requirements, a kind of low-intensity, rapidly solidified and hard plastic-like sealing slurry is developed, and its performance parameters are obtained. It is enough to stem grouting and to consume energy by filling slurry materials between grouting pipe and bore hole pipe wall based on the grouting mechanism. The bottom-up pulling force which provides the basis for choosing pulling machines for construction is calculated. In addition, if you turn the grouting pipe continuously during the process of grouting, the work efficiency can be improved and the grouting pipe can be smoothly promoted to avoid locking accidents even in deep borehole cases without pipe drawing machines. Through the tests on the deep soft stratum in the bay area of Tuokou Hydropower Station, the slurry materials achieve the desired effect. Theoretical study and engineering practice show that it's feasible to adopt slurry sealing technology and to implement high-pressure grouting in soft stratum, and that the construction techniques by means of stemming slurry material can meet requirements. Source

Chuanli G.,China Institute of Water Resources and Hydropower Research | Yuan W.,China Institute of Water Resources and Hydropower Research | Yuan W.,Wuling Power Corporation | Yeping Y.,China Institute of Water Resources and Hydropower Research | Hailong C.,China Institute of Water Resources and Hydropower Research
Lecture Notes in Electrical Engineering

The use of partial discharge (PD) on-site monitoring as an indicator of HV equipments insulation condition is well known. However, the existence of external interferences has greatly reduced the credibility of PD on-site measurement technology of HV equipments. This paper describes practical application of the UHF PD detection method on a new oil-immersed power transformer and to suppress interference, an internal UHF sensor (antenna) was designed and successfully installed to power transformers for its insulation condition assessment which can effectively avoid the frequency band of the external interferences. As the frequency band of this UHF sensor was 300~1500MHz, envelope detection technique was used to extract UHF signals excited from PD sources inside the transformer. The results of MATLAB simulations have shown that UHF PD signals can be effectively extracted by this method. Using the monitoring system established in this paper, plenty of external interferences pulses and UHF PD pulses were recorded and investigated, PD pulses with small amplitude can be effectively detected, which reveal that UHF PD measurements can effectively measure small level of discharges with good sensitivity. © 2011 Springer-Verlag Berlin Heidelberg. Source

Xu H.-N.,University of Sichuan | Pang X.-B.,Wuling Power Corporation | Xu J.,University of Sichuan | Liu J.-F.,University of Sichuan
Sichuan Daxue Xuebao (Gongcheng Kexue Ban)/Journal of Sichuan University (Engineering Science Edition)

Tri-axial creep test was carried out on borehole sampling basis in order to reveal the creep characteristics of purple silty mudstone in the Upper Silurian in the center and west of North Tianshan, and provide the basis for the designing, construction and long-term stability evaluation of the proposed deep and long tunnel. Test was performed on five rock tri-axial creep test machines with the confining pressure of 0, 5, 10, 20 and 30 MPa, respectively. Through the study, the following resulted were achieved. Rock creep characteristics was proved to be describable by the Xiyuan Model and a creep constitutive equation was establish for this kind of mudstone. The creep parameters were gained by calculating them based on creep curves. Long-term rock strength was obtained by superposition theorem and isochronous curve method, and the confining pressure effect was revealed on the long-term strength. The creep parameters increased with the increase of confining pressure, and the difference between long-term rock strength and instant rock strength increased by 25% under uni-axial pressure and 52% under tri-axial pressure of 30 MPa as the confining pressure increased. The long-term shearing strength decreased by 60%(cohesion) and 36% (internal friction angle) compared with the instant shearing strength. These results provided a scientific basis for the engineering construction, and the test and result collation methods were available for other similar construction and research. Meanwhile, physical and mechanical property of silty mudstone was also obtained through routine tests, which helps to apply creep test result to other similar projects. Source

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