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Zhang Q.-L.,Changjiang River Scientific Research Institute | Zhang Q.-L.,Research Center on Water Engineering Safety and Disaster Prevention of | Wu H.-G.,Wuhan University
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2012

The development in the research and application of spiral case structure with a membrane(SCSM) in hydroelectric power plant, is summarized. It is indicated that SCSM is the trend in development of selecting the embedding type for spiral case. Two significant advances are pointed out: the joint stressing of spiral case and surrounding concrete, the sliding friction between them. The nonlinear mechanical behavior of membrane material as a factor influencing significantly the SCSM research should be considered in the future. The influences of membrane's material and space property on the structural performances of SCSM are respectively stated, and on that basis the existing problems of the SCSM research are concluded. Finally, it is suggested that the of concepte control should be the focus of research in SCSM and the membrane could be regarded as a controlling measure. To explore the theory and measure for controlling the structural performances of spiral case structure from the viewpoint of effect of membrance should be the important topics of research in this field. Source


Zhang Q.-L.,Changjiang River Scientific Research Institute | Zhang Q.-L.,Research Center on Water Engineering Safety and Disaster Prevention of | Wu H.-G.,Wuhan University
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2013

When a steel spiral case is embedded with its top portion covered with a compressible membrane, the membrane is probably responsible for weakening the hold of concrete on the steel spiral case. That may have an influence on the contact between the steel spiral case and the concrete, and even cause a gap between them. First, this paper discussed potential origins of gaps from the view of statics. Then, FEM-based nonlinear numerical simulations were performed to clarify key structural factors influencing the contact state. The results of this study indicate that three structural factors play leading roles in weakening the hold of concrete. They are: (1) a weak friction between a steel spiral case and concrete; (2) a wide membrane-covered range in c-cross-sections and (3) a small compression stiffness of a membrane. However, routine values of parameters concerning the above first two factors do not have significant effect on the contact state. Correspondingly, the contact state is dependent on the third factor mentioned above markedly. In general, therefore, it seems that appropriately reducing a membrane's compression stiffness is a compromise but useful design technique. It will be constructive in ensuring the integrity of a hydropower house substructure. Source


Zhang C.,Central South University | Cao P.,Central South University | Wang Y.,Central South University | Wang Y.,Hefei University of Technology | And 2 more authors.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2013

According to plagioclase-hornblende rock in Jinchuan deep underground mine uniaxial compression creep test results, after selection typical creep curves, it is found that viscoelastic and viscoplastic deformation are significantly less than instantaneous deformation, elastic after-effect is not obvious after unloading. Under 5.1 MPa of uniaxial stress, rock samples show pure elastic properties in natural condition. Under water condition, both instantaneous uniaxial compressive strength σ'b and long-term strength σ'∞ are generally lower than nature condition, σ'∞ approaches deep high underground stress, therefore, under high stress conditions in deep underground, especially joints, fractured rock mass, should pay particular attention to drainage, so as to prevent rock deformation and damage due to long-term strength σ∞ reduction in roadway. Instantaneous elastic and plastic strain εme, εmp increases with stress, but the speed decreases, plastic deformation characteristics becomes more conspicuous in water-saturated condition. Under the same stress, water-saturated condition's creep is higher than that of natural condition, and strain rates are generally faster, two conditions's creep rates all turn stable in 20-30 h, rate curves approach each other with stress increases and micro-cracks compact, rock samples turn into a relative hardening stage. While stress reaches 66.3 MPa, water-saturated condition's strain rates accelerate relatively, curves first move down-left, then back to upper-right, but in natural condition, strain rate curves generally move to upper-right. Finally, in the light of creep data characteristics, empirical equation γ=ασk is introduced to fit the experimental data. The results prove that the empirical creep model is correct. The creep experimental research of plagioclase hornblende rock in Jinchuan underground mine can provide effective help for analyzing deep roadway rheological stability and support optimization. Source


Li B.,Changjiang River Scientific Research Institute | Li B.,Research Center on Water Engineering Safety and Disaster Prevention of | Gu C.-S.,Hohai University | Wu J.-K.,Hebei University of Engineering
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2013

For the effects of vibration and age, the mechanical parameters of roller compacted concrete dam (RCCD) have gradual change characteristics in space and time, which make a complex variation on the mechanical parameters of RCCD. It is difficult to obtain accurately the mechanical parameters and interface thickness. In this paper, aiming at small difference of elastic modulus and creep among adjacent compacted layers, the determination method of the zone-merged age in RCCD is firstly studied, then considering the gradual change property of RCC in space, the elastic calculation parameter analysis model of typical roller compacted layer is established by using compound material mechanics, and the elastic calculation parameter analysis model of zone-merged body is established using zone-merged algorithm. Finally, on the basis of back analysis of zone-merged equivalent elastic mechanical parameters of RCCD, elastic gradual change parameters of RCCD are solved by using particle swarm optimization algorithm. The engineering example shows that the proposed method is feasible and effective. Source


Zhang Q.,Changjiang River Scientific Research Institute | Zhang Q.,Research Center on Water Engineering Safety and Disaster Prevention of | Zhang Q.,Wuhan University | Wu H.,Wuhan University | And 2 more authors.
Yingyong Lixue Xuebao/Chinese Journal of Applied Mechanics | Year: 2011

The engineering has not reached a consensus on how to determine a proper plane covering range of membrane for spiral case in a hydropower station up to now. Four factors including stay ring's displacement and deformation, stay ring's shear capability, generator pedestal's displacement and deformation, flow channel's torsional strength are considered to solve this problem by using three-dimensional finite element method (FEM). The result suggests that if the primary design objective of spiral case structure is to control stay ring and generator The result suggests that if the primary design objective of spiral case structure is to control stay ring and generator pedestal's displacement and deformation, the plane covering end of membrane is suitable to be located between 135° cross section and 180° cross section of spiral case. However, with regard to enhancing stay ring's shear capability and improving flow channel's loading condition, the plane covering end of membrane is suitable to be located between 0° cross section and 90° cross section, or after 270° cross section of spiral case. In view of the fact that the stay ring's shear capability can be enhanced and the flow channel's loading condition can be improved with some specific measures, the stay ring and generator pedestal's nonuniform deformation should take priority when determining the plane covering range of membrane for a spiral case. Source

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