Ma Y.,Wuhan University |
Ma Y.,Central Southern Geotechnical Design Institute Co. |
Wei Z.-Y.,Wuhan University |
Wei Z.-Y.,Hydro China Huadong Engineering Corporation |
And 3 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2014
With the development of foundation pit scale toward larger and deeper, the traditional single pile, the pile anchor supporting structure, pile brace are subject to certain restrictions, in the case of higher control requirements in the deformation and which should not be used within support and anchor, double-row piles can play a better role. Double-row piles consist of two rows of parallel retaining piles, top beam and connecting beam formed a space envelope system. High stiffness, good stability, small deformation and benefit for erect excavation are the strengths, so double-row piles are widely used in deep foundation pit engineering. In the new specification Technical Specification for Engineering of Foundation Excavation (DB42/T159-2012) increases the foundation retaining structure with double-row piles in related chapters. On the basis of the double-row piles calculation model proposed in the new pit specification of Hubei province, a simple, practical design and calculation software of double-row piles for foundation pit (hereinafter referred DESDROP) has been developed by VB.NET. The research and development of this software is to cooperate with new rules for implementation. The displacement, internal force and stability of the double-row piles are analyzed by the software; and the soil pressure, displacement, bending moment, shear force diagram also can be seen through the query result under any working conditions. The software has been applied to Jindimingjun foundation pit engineering. The results show that the operation speed of DESDROP software is fast, calculation results can meet the needs of the double-row piles supporting design.
Chen S.,North China University of Water Conservancy and Electric Power |
Ding B.,Hydro China Huadong Engineering Corporation
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011
In view of the character of concrete structure of inverted siphon underground culvert and the problem of concrete crack in the period of construction, this paper introduced the main factors which influence the temperature and stress of concrete structure, and the main cause of crack is closely related to placing delaminating, interval time, cold wave strike, diurnal amplitude, superficial thermal insulation and cooling pipe. A case is presented where the 3D FEM simulation of thermal field and stress field of concrete and the numerical algorithm of pipe cooling are adopted to study the sensitivity degree of these factors. It is considered that placing delaminating and interval time greatly Influence the Integrity Deformation Compatibility of concrete structure, and cold wave strike and diurnal amplitude induce adverse effects to crack prevention of surface, and suitable thermal Insulation and cooling pipe greatly improve anti-crack performance of concrete structure. Finally, the paper put forward temperature control measures for crack prevention based on the research results.
Liu F.,Ocean University of China |
Chen Z.,Zhejiang Ocean University |
Li W.,Hydro China Huadong Engineering Corporation
Journal of Vibroengineering | Year: 2012
The direct mode shape expansion method is an iterative technique, one can conclude that the convergence performance maybe challenged when applied to three-dimensional structures. In addition, mode shape values at different DOFs (degrees-of-freedom) sometimes are not in a same order of magnitude, which will produce much error for the estimation of small values of unmeasured mode components. Therefore this paper proposed a non-iterative mode shape expansion method based on coordinate decomposition technique. The advantage of coordinate decomposition is that the unmeasured components of mode shape values could be estimated with different weighting coefficients, even in a physical meaningful interval. Numerical studies in this paper are conducted for a 30-DOF cantilever beam with multiple damaged elements, as the measured modes are synthesized from finite element models. The numerical results show that the approach can estimate unmeasured mode shape values at translational and rotational DOFs in x, y and z directions with different weighting coefficients, respectively; and better mode shape expansion results can be obtained when proper constraints are employed. A numerical three dimensional structure is also investigated, and results indicate that the estimation of unmeasured components can be improved by imposing reasonable constraints based on the coordinate decomposition technique, even only translational DOFs of two diagonal nodes of the first floor are measured. © Vibroengineering. Journal of vibroengineering.
Zhang B.,Tsinghua University |
Jiang Y.,Tsinghua University |
Yang J.,Hydro China Huadong Engineering Corporation |
Li X.,Hydro China Huadong Engineering Corporation |
Chen S.,Tsinghua University
Gaodianya Jishu/High Voltage Engineering | Year: 2013
Due to the large scale, scattered arrangement, loose connection, and non-uniform soil of a grounding system of hydroelectric power plant, the longitudinal impedance characteristics of grounding materials may obviously affect the grounding resistance. Consequently, according to the distribution characteristics of grounding system in hydroelectric power plants, we established a voltage-different grounding system model by taking the effects of the longitudinal impedance into consideration and using the field-circuit coupling method, and analyzed the influence of commonly used grounding materials such as copper and steel on the ground impedance of large-scale hydropower plant with different soil models and different current injected points. Moreover, we put forward a measure to reduce the ground impedance by using suitable material. The analysis results show that, although grounding material has little effect on the grounding resistance of substations, its effect on that of hydropower grounding system is remarkable. Traditional formula for analyzing the grounding system is not suitable for hydroelectric power plants, and numerical methods are necessary. When the current injected point is located on bank, the difference of the grounding resistance between copper and steel is up to more than two times. Copper electrode can significantly reduce the grounding resistance of a hydropower plant. It is recommended to use copper conductors to connect different parts of a grounding system, which is both economical and effective.
Qiang S.,Hohai University |
Wu C.,Hohai University |
Wu C.,Changjiang Institute of Surving |
Zhu Z.,Hydro China Huadong Engineering Corporation
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2015
Aiming at the coordination problem between the calculation accuracy and efficiency in the temperature simulation for mass concrete containing cooling pipe, a new composite element algorithm is proposed. The concrete around the cooling pipe is recognized as two regions which are a nonlinear temperature region (region A) and a linear temperature region (region B) separately. The water temperature in pipe segment (region water) is considered as well. According to the relationship between concrete temperature in region A and the distance to pipe wall, additional with the functional analysis of every region, a new composite model including a concrete sub-element and a water sub-element was deduced. Numerical samples show that the temperature developments by finite element method and composite element method are absolutely same. The maximum numerical difference is in 2℃ with an adiabatic temperature rise of 50℃ or 60℃, which was caused mainly by the radius of region A. As for the efficiency, the total simulation time cost of composite element method is 50% of the finite element method for the sample in this paper. Compared with the former composite element model for cooling pipe, the proposed algorithm can improve the temperature field calculation accuracy of the concrete around pipe while no necessary to refine the mesh. And the computation efficiency is also satisfying. ©, 2015, China Water Power Press. All right reserved.
Xu L.,Hydro China Hua Dong Engineering Corporation |
Xue Y.,Hydro China Hua Dong Engineering Corporation |
Gong Y.,Hydro China Hua Dong Engineering Corporation |
Chen G.,Xi'an University of Technology
Resources, Environment and Engineering - Proceedings of the 2014 Technical Congress on Resources, Environment and Engineering, CREE 2014 | Year: 2015
In order to investigate the effect of bubble deformation on lift force coefficient which plays a crucial role in determining the lateral migration of bubble, Coupled Level Set and Volume of Fluid method was induced to simulate the lift force on the bubbles of 0.134 ≤Eo ≤8.588. By comparing with the results of the model experiments, it can be seen that: the bubbles were found oscillate around the centerline and the instantaneous CL was found to fluctuate around a fixed value for the single bubble rise; It was observed that individual bubble deformation led to increased bubble-bubble interaction and as a result, the fluctuation of CL increased. The time-averaged C L of all the bubbles was found to be very small and then stabilized as compared with the characteristic CL obtained from the single bubble rise.
Liu F.,Ocean University of China |
Li H.,Ocean University of China |
Li W.,Hydro China Huadong Engineering Corporation |
Applied Ocean Research | Year: 2014
Usually only a few of lower-order modes of interest extracted from stochastic response under the excitation of environmental forces, such as waves, winds or ice, could be obtained from sea tests of offshore jacket platforms; and what is more serious, this lower-order modal information is often buried in noises, which will be a challenge for identifying the modal parameters of interest. In this article, we propose an improved modal parameter identification method by reconstructing a new response consisting of only lower-order frequencies, and apply this method to a real offshore jacket platform located in the north of Liaodong Bay, China. One theoretical contribution is that the fainter modes could be isolated as one expected by defining reasonable pass band width and centering frequency. The elimination of noisy modes is realized by reconstructing the Eigensystem Realization Algorithm (ERA) block data matrix using the reconstructed responses. The other contribution is that the difficulty in judging whether an identified mode is due to noise or a genuine one has been resolved properly. A numerical offshore jacket platform is chosen to illustrate the procedure and demonstrate the performance of the proposed scheme. Numerical results indicate that: (1) lower-order frequencies can be isolated successfully using FFT filtering, and unexpected peaks in auto spectral density can be removed effectively using our smoothing procedure; (2) modal parameters of interest such as frequencies and damping ratios both can be identified properly by reconstructing Hankel matrix with a small dimension of ERA. Using sea test data measured from accelerometers mounted at the joints of the test platform, we find that our approach outperforms traditional ERA because no noisy modes are introduced. Though traditional ERA could identify two of the first three modal frequencies and damping ratios using the same segment of measured sea data, the dimension of Hankel matrix reaches 1000 times 1000, with a large amount of noisy modes. The achievement may contribute to two research areas: (1) signal processing when fainter frequencies are expected to be isolated, and (2) modal parameters identification when amount of noisy modes exist using traditional methods, such as ERA. Specifically, accuracy and efficiency of modal parameters identification (interested) of offshore jacket platforms can be improved. © 2014 Elsevier Ltd.
Gan P.,Zhejiang University |
Zhao Y.,Zhejiang University |
Tang X.,Zhejiang University |
Zou J.,Hydro China Huadong Engineering Corporation |
Pan C.,Hydro China Huadong Engineering Corporation
ITA-AITES World Tunnel Congress 2016, WTC 2016 | Year: 2016
The north segment of the Zizhi Tunnel that consists of twin tunnels was excavated at a shallow depth in soft ground using the Shallow Tunneling Method. Based on continuous field measurements, the development histories of surface settlement were analyzed first. The observed development process could be roughly divided into three stages and the influence of river was evidenced. Transverse and longitudinal surface settlements above the twin tunnels were then fitted with empirical models. The obtained trough width parameters in transverse and longitudinal direction (it and il) and the volume loss (VLs) were presented and discussed. Additionally, surface settlement was compared with the crown settlement. The relationship between surface and crown settlement behaved in two different ways inside and outside the river-affected region. The findings in this project give references for predicting surface settlements in similar tunneling condition. Copyright © (2016) by the Society for Mining, Metallurgy and Exploration All rights reserved.
Xu L.,Hydro China Hua Dong Engineering Corporation |
Xue Y.,Hydro China Hua Dong Engineering Corporation |
Li M.,Hydro China Hua Dong Engineering Corporation
IET Conference Publications | Year: 2014
The coupled volume of fluid and level set method was applied to simulate dynamic characteristics of double bubbles; the bubble behavior was studied in five conditions. According to numerical simulation, it can be seen that: the different arrangement, distance and deformation would produce different effects on bubbles. The interactions decreased with increase in bubble distance when horizontal dispersed, and it can be neglected when bubble distance was 1.5 times of average diameter. If the bottom bubble was in wake of the upper bubble, the below one would accelerate until the merger occurs when vertical dispersed; It was observed that bubble deformation led to increased bubble interactions and as a result, the fluctuation of CL was increased. The time-averaged CL of all the bubbles was found to be very small and then stabilized as compared with the characteristic CL obtained from the single bubble rise.
Liu T.-Y.,Central South University |
Liu T.-Y.,Hydro China Huadong Engineering Corporation |
Cao P.,Central South University |
Zhang L.-F.,Hydro China Huadong Engineering Corporation |
And 2 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2012
Initial cracking law and evolution law of stress intensity factor at the tip of the branch crack of compression-shear fractured rock under high seepage pressure are discussed. The critical water pressure value and the initial cracking intensity criterion of the fractured rock mass under high seepage pressure are established when tension-shear failure occurs. The cracking characteristics under different water pressures indicate that the existence of osmotic pressure aggravates the growth of branch crack; and the branch crack propagation under high osmotic pressure will convent from stable expansion to unstable expansion and cause the shear failure of the crag bridge at the branch crack tip; simultaneously the branch crack interaction is considered, the crag bridge's cutting penetration damage mechanical model of the compression-shear rock under the high seepage pressure is established. Finally, the flexibility tensor of the rock mass' initial damage and its damage evolution based on damage mechanical effect of fractured rock are studied. Then a damage evolution equation of fractured rock under high seepage pressure is proposed. The theory provides the basis for the quantitative investigation about the compression-shear destruction of fractured rock under high seepage pressure.