The difficulty of selecting appropriate rheological model and parameters for the alternating distribution of soft and hard rock layers was often encountered due to the unhomogeneity, discontinuity and anisotropy of ro...The difficulty of selecting appropriate rheological model and parameters for the alternating distribution of soft and hard rock layers was often encountered due to the unhomogeneity, discontinuity and anisotropy of rock mass. The Burgers and generalized Kelvin models were applied to the soft and hard rock respectively and the rheological parameters were obtained based on the method of optimum separation. By using the simulated code FLAC^(3D), the stability of surrounding rocks of a certain underground plant was analyzed. The effect of surface load and weakening the parameters intensity of argillaceous and bioclastic interlayers between soft and hard rock on rheological behavior of layer composite rock mass was investigated. The results indicate that the rheological characteristics of soft and hard rock layer in composite rock mass can be described well with above two rheological models.展开更多
A structure of gradient hard coatings( Ti,TiN,TiCN and TiAlN) is designed,and residual stress is simulated by a finite element method with ANSYS. The influence of the realistic situation including load and temperature...A structure of gradient hard coatings( Ti,TiN,TiCN and TiAlN) is designed,and residual stress is simulated by a finite element method with ANSYS. The influence of the realistic situation including load and temperature on the residual stress of the coatings is investigated. Simulated results show that the realistic situation strongly affects the residual stress. To be specific,i) The main residual stress concentrates on the coatings prepared on YG8 substrate,and the residual stress and its gradient of the coatings are bigger than that of the substrate; ii) TiAlN and TiCN coatings have better resistance compression than that of TiN coatings in the same condition; iii) The improved multilayer structure of the gradient hard coatings produces weaker residual stress but higher anti-pressure of the substrate.展开更多
This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and co...This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.展开更多
基金Supported by the National Natural Science Foundation of China (50374049)
文摘The difficulty of selecting appropriate rheological model and parameters for the alternating distribution of soft and hard rock layers was often encountered due to the unhomogeneity, discontinuity and anisotropy of rock mass. The Burgers and generalized Kelvin models were applied to the soft and hard rock respectively and the rheological parameters were obtained based on the method of optimum separation. By using the simulated code FLAC^(3D), the stability of surrounding rocks of a certain underground plant was analyzed. The effect of surface load and weakening the parameters intensity of argillaceous and bioclastic interlayers between soft and hard rock on rheological behavior of layer composite rock mass was investigated. The results indicate that the rheological characteristics of soft and hard rock layer in composite rock mass can be described well with above two rheological models.
基金Supported by the National High Technology Research and Development Programme of China(No.2012AA09A203)Project of Sichuan Education Department(No.14ZA0321)
文摘A structure of gradient hard coatings( Ti,TiN,TiCN and TiAlN) is designed,and residual stress is simulated by a finite element method with ANSYS. The influence of the realistic situation including load and temperature on the residual stress of the coatings is investigated. Simulated results show that the realistic situation strongly affects the residual stress. To be specific,i) The main residual stress concentrates on the coatings prepared on YG8 substrate,and the residual stress and its gradient of the coatings are bigger than that of the substrate; ii) TiAlN and TiCN coatings have better resistance compression than that of TiN coatings in the same condition; iii) The improved multilayer structure of the gradient hard coatings produces weaker residual stress but higher anti-pressure of the substrate.
文摘This paper presents an assessment of the hydrochemical characteristics of groundwater in Northern Gezira State, Central Sudan. The approaches followed here include the chemical analyses for major ions chemistry and construction of hydrochemical maps of total dissolved solids (TDS), sodium (Na +), bicarbonate (HCO 3 -), and chloride (Cl -) ions. The hydrochemical characteristics of the groundwater in each aquifer and management consideration are discussed. Sources of major ions in groundwater are analyzed. The hydrochemical maps of important species are constructed. The relationship of groundwater to use is elaborated. High concentrations of the chemical and hydrochemical constituents and the occurrence of calcretes (CaCO 3) in upper zones suggest a long history of evaporation and increasing leachates.
