Time filter

Source Type

Zhang G.-R.,Nanjing Hydraulic Research Institute | Cheng W.,Central Southern China Electric Power Design Institute
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Aimed at regulated scheme of Three Gorges Reservoir and extreme rainfall events, 10 working conditions were set for stability analysis of bazimen landslide of Zigui county. Transit seepage due to associative action of reservoir water lever fluctuations from 175 to 145 and rainfall infiltration was simulated adopted by SEEP/W software. And by using SLOPE/W software, the computed transit pore water pressures were used for limit equilibrium analysis of this landslide, then the landslide stability factors of different work conditions (different rainfall intensity) were decided and the rainfall could be used to predict landslide at last. The stability study showed it would have a great influence on landslide stability when the rainfall is greater than 150 mm/d, and rainfall infiltration had time delay. In the same condition of rainfall, the influence of one day's rainfall intensity on landslide stability had greater than five day's rainfall intensity. During the process of water lever descending from 175 m to 145 m, the landslide would be instability when the critical rainfall was 100 mm/d. That is to say, the landslide failure probability was high during the rapid drawdown. During the process of water lever ascending from 145 m to 175 m and the stable water lever of 175 mm, the landslide would be instability while the critical rainfall was reach to 200 mm/d, that means the landslide failure probability was low under the above two conditions. The results of moisture analysis on landslide showed that it mainly influenced upper soil by rainfall, and lower soil's moisture was controlled by underground water, which indicated rainfall was accessible to cause shallow slope and local slope.

Huang D.,Wuhan University | Wu G.,Central Southern China Electric Power Design Institute | Ruan J.,Wuhan University
IEEE Transactions on Plasma Science | Year: 2015

The static and dynamic voltage distribution characteristics and voltage sharing design of a 126-kV modular triple-break vacuum circuit breaker (VCB) was discussed in this paper. The finite-element method and power frequency tests were used to calculate and verify the static voltage distribution ratios and distributed capacitance parameters of multi-break VCBs, respectively. A model combining the post arc current model and equivalent capacitance model was proposed for simulations of dynamic transient recovery voltage (TRV) distribution characteristics of the triple-break VCB. The simulation results indicated that besides the stray capacitances, the TRV sharing design should take the influence of residual charge (RC) into account, and the influence of RC on the TRV distribution is relevant to the differences of RC parameters among the series interrupters. Therefore, the appropriate value of grading capacitors should meet the requirement of the worst case. Based on the investigation of this paper, a 126 kV U-shaped triple-break VCB prototype with 1000 pF grading capacitors has been produced, and the successful large current breaking tests indicate the good breaking capacity and suitable voltage sharing design of the triple-break VCB. © 2015 IEEE.

Chen Y.,Hubei Engineering University | Zhou C.,Hubei Engineering University | Mao X.,Central Southern China Electric Power Design Institute | Hu R.,Hubei Engineering University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010

To reduce the seepage of the underground opening in Shuibuya hydropower project and improve the seepage stability of the surrounding rocks, a seepage control system including grouting curtain, drainage hole array and drainage tunnels is designed and deployed. The long-term seepage control effects of the surrounding rocks of the underground powerhouse are performed by a stationary seepage analysis method combining the variational inequality formulation of Signorini's type with an adaptive penalty Heaviside function to guarantee the numerical stability and convergence. Meanwhile, the difficulty in finite element mesh generation is reduced and the calculation time and modeling accuracy are balanced with a global model of equivalent modeling and a submodel of accurate modeling for drainage hole array. Intuitive criteria for assessment of the reasonability of the numerical results are established, namely stationary seepage free surface in any homogeneous medium must be continuous, smooth and can not be return-curved, unless it intersects with an interface between two media of distinct permeabilities. By making comparison with the measurements of pore water pressures in the surrounding rocks, the feasibility and effectiveness of the proposed model are demonstrated. The reasonability of the design of the seepage control system and the possibility of its further optimization are illustrated. The research results are helpful for optimization design of the seepage control system in similar projects.

Yang X.-L.,Wuhan University of Science and Technology | Ding J.-H.,Central Southern China Electric Power Design Institute | Hou H.,Wuhan University of Technology
Natural Hazards | Year: 2013

Flood risk evaluation and prediction represents an essential analytic step to coherently link flood control and disaster mitigation. The paper established a hybrid evaluation model based on fuzzy analytic hierarchy process (AHP) and triangular fuzzy number. It comprises flood risk evaluation and prediction to obtain risk factors ranking and comprehensive flood risk prediction, and then analyzed flood risk response measures. A case study is proposed entailing a flood risk evaluation and prediction in the Lower Yangtze River region. The evaluation results showed that the proposed evaluation and prediction model was capable of adequately representing the actual setting. In addition, a comparison with the previously described AHP and trapezoidal fuzzy AHP, and experimental results are encouraging, which fully demonstrates the effectiveness and superiority of the proposed model. © 2013 Springer Science+Business Media Dordrecht.

Liu H.,China Earthquake Administration | Bo J.,China Earthquake Administration | Bo J.,Institute of Disaster Prevention | Yang J.,Central Southern China Electric Power Design Institute
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012

The pseudo-static method for the seismic stability evaluation of rock slope is recommended by most codes at home and abroad, but it neglects the effects of dynamic properties of rock mass and most of earthquake ground motion characters. Furthermore, the method of earthquake time-history reasonably considering the effects of main factors is time-consuming and laborious. Nowadays, such simplified methods are lacking in the seismic stability evaluation of rock slope, which can reasonably consider the impacts of dynamic properties of rock mass and the characters of earthquake ground motion. Thus, the relation between the seismic and pseudo-static safety factors is constructed and two simplified methods, which can comprehensively utilize respective advantages of the time-history method and pseudo-static method for determining the seismic safety factor of rock slope, are put forward as follows: (1) The statistical models of seismic safety factor of rock slope and pseudo-static safety factor, peak acceleration are provided for the critical slopes. (2) The rectified coefficients of seismic safety factor of rock slope and pseudo-static safety factor are derived, and corresponding correction schemes are suggested for general slopes. The execution procedures of the simplified methods are illustrated using the method combining finite elements with limit equilibrium method through a typical rock slope. The results prove the feasibility and rationality of the suggested methods. The simplified methods proposed provide the valuable methods and the important reference for rapid evaluation aftershock of critical slopes and seismic stability evaluation of general slopes.

Discover hidden collaborations