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Xu H.,China Institute of Water Resources and Hydropower Research
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2012

This paper puts forth a theory of cavitation bubbles conglomeration endangering stability of hydraulic machinery with a brief derivation and analysis. This theory includes endangering of cavitation bubbles conglomeration, endangering scope, mechanism of endangering, power source of endangering, and two main endangering forms. The effect of air admission and its related principles are interpreted by the theory, and the role of the theory in study of hydraulic machinery stability is discussed. © right. Source


Chen G.Q.,Peking University | Wu Z.,Peking University | Zeng L.,China Institute of Water Resources and Hydropower Research
International Journal of Engineering Science | Year: 2012

For the most typical two-layer wetland with free-water-surface-effect, analytically explored in this paper is the environmental dispersion in terms of the longitudinal evolution of the depth-averaged concentration. Taylor's classical analysis for soluble matter dispersion in a single phase fluid flow is rigorously generalized for the two-layer case of a wetland flow to develop the dispersion model. The velocity profile of the fully developed flow through the wetland is derived, with that for the single-layer wetland flow included as a special case. Aris's method of concentration moments is applied to determine the dispersivity with an asymptotic time variation. For typical contaminant constituents of chemical oxygen demand, biochemical oxygen demand, total phosphorus, total nitrogen and heavy metal, the process of dispersion is shown characteristic of a hierarchical structure in the critical length and duration of the contaminant cloud. © 2011 Elsevier Ltd. All rights reserved. Source


Yang K.-L.,China Institute of Water Resources and Hydropower Research
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2011

A new type air-valve surge tank for controlling liquid column separation occurred to water supply projects is developed. It consists of a vertical short pipe and air valves installed on the top. The tanks are installed on the main to form a series of local convexities. They are full of water during normal operations. As soon as the water pressure drops to under the atmospheric pressure, air will be sucked into the tank through the air valve to form an air chamber. The air in the tank will be released slowly while the water pressure is greater than the atmospheric pressure. The application indicates that the tank not only can control the negative pressure during hydraulic transients, but also the positive pressure. Source


Zhang X.,University of Newcastle | Krabbenhoft K.,University of Newcastle | Sheng D.,University of Newcastle | Li W.,China Institute of Water Resources and Hydropower Research
Computational Mechanics | Year: 2015

In this paper, an actual landslide process that occurred in Southern China is simulated by a continuum approach, the particle finite element method (PFEM). The PFEM attempts to solve the boundary-value problems in the framework of solid mechanics, satisfying the governing equations including momentum conservation, displacement-strain relation, constitutive relation as well as the frictional contact between the sliding mass and the slip surface. To warrant the convergence behaviour of solutions, the problem is formulated as a mathematical programming problem, while the particle finite element procedure is employed to tackle the issues of mesh distortion and free-surface evolution. The whole procedure of the landslide, from initiation, sliding to deposition, is successfully reproduced by the continuum approach. It is shown that the density of the mass has little influence on the sliding process in the current landslide, whereas both the geometry and the roughness of the slip surface play important roles. Comparative studies are also conducted where a satisfactory agreement is obtained. © Springer-Verlag Berlin Heidelberg 2014. Source


Yang G.-H.,China Institute of Water Resources and Hydropower Research
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

Soil nailing wall is a more economical way of retaining and protection and has been widely used in engineering practice; but the design theory is still relatively deficient. This paper analyzes the main problems in the design of soil nailing retaining wall, namely, soil nail forces and displacement calculation; based on practical engineering experiments and considering the affect of the construction process with the incremental method, supposing that the active earth pressure acted on the retaining wall are equal to the sum of the soil nail forces, a simple method for calculating soil nail forces is proposed. Basing on the elastic theory, the formula for calculating the displacement of the soil nailing wall under excavation is put forward. The rationality of the method and formula is checked by engineering case studies. Source

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