Aim To study the elastic plastic dynamical constitutive relations about a jointed rock mass under explosion load and its computer simulation. Methods\ Stress history is taken into account and stresses will follow ch...Aim To study the elastic plastic dynamical constitutive relations about a jointed rock mass under explosion load and its computer simulation. Methods\ Stress history is taken into account and stresses will follow changes in time during a period of explosion load. According to the principle of static force balance, the corresponding nodal concentrated force is calculated and the nodal displacement is counted. The elastic plastic dynamic finite element equations are thus obtained. Results\ A finite element method is given for a jointed rock mass under explosion load. Conclusion\ The problem of large plastic deformation for jointed rock mass on blasting was efficiently resolved through dynamic finite element analysis and the range of damages by blasting simulated, and this pushes forward the problem to engineering practice.展开更多
A new approach named as steel pile method is innovatively proposed in this study to control severe floor heaves in gob-side entry retaining. It is required that the steel piles be installed in the floor corners with a...A new approach named as steel pile method is innovatively proposed in this study to control severe floor heaves in gob-side entry retaining. It is required that the steel piles be installed in the floor corners with a certain interval before the influence of the dynamic pressure induced by current panel extraction. Using numerical simulation and theoretical analysis, this study investigated the interaction between the steel piles and the floor rocks during the service life of the steel piles, and revealed the mechanism of the steel piles in controlling floor heaves. The effect of the steel pile parameters on the control of floor heaves was presented and elaborated. It is found that the effectiveness of the steel piles in controlling floor heaves can be enhanced with greater installed dip angle, longer length and smaller interval of the steel piles.Compared with traditional methods, e.g., using floor anchor bolts and floor restoration, the advantages using steel pile were successfully defined in terms of controlling effect and economic benefits. It is hoped that the proposed method can contribute to the development of gob-side entry retaining technique.展开更多
In the present study, a new approach is applied to the cavity prediction for two-dimensional （2D） hydrofoils by the potential based boundary element method （BEM）. The boundary element method is treated with the so...In the present study, a new approach is applied to the cavity prediction for two-dimensional （2D） hydrofoils by the potential based boundary element method （BEM）. The boundary element method is treated with the source and doublet distributions on the panel surface and cavity surface by usethe of the Dirichlet type boundary conditions. An iterative solution approach is used to determine the cavity shape on partially cavitating hydrofoils. In the case of a specified cavitation number and cavity length, the iterative solution method proceeds by addition or subtraction of a displacement thickness on the cavity surface of the hydrofoil. The appropriate cavity shape is obtained by the dynamic boundary condition of the cavity surface and the kinematic boundary condition of the whole foil surface including the cavity. For a given cavitation number the cavity length of the 2D hydrofoil is determined according to the minimum error criterion among different cavity lengths, which satisfies the dynamic boundary condition on the cavity surface. The NACA 16006, NACA 16012 and NACA 16015 hydrofoil sections are investigated for two angles of attack. The results are compared with other potential based boundary element codes, the PCPAN and a commercial CFD code （FLUENT）. Consequently, it has been shown that the results obtained from the two dimensional approach are consistent with those obtained from the others.展开更多
Coal burst is a dynamic release of energy within the rock （or coal） mass leading to high velocity expulsion of the broken/failed material into mine openings. This phenomenon has been recognised as one of the most ca...Coal burst is a dynamic release of energy within the rock （or coal） mass leading to high velocity expulsion of the broken/failed material into mine openings. This phenomenon has been recognised as one of the most catastrophic failures associated with the coal mining industry, which can often lead to injuries and fatalities of miners as well as significant production losses. This paper aims to examine the mecha- nisms contributing to coal burst occurrence, with an emphasis on the energy release concept. In this study, a numerical modelling study has been conducted to evaluate the roles and contributions of differ- ence energy components. The energy analysis presented in this paper can help to improve the under- standing of energy release mechanisms esoeciallv under Australian conditions.展开更多
文摘Aim To study the elastic plastic dynamical constitutive relations about a jointed rock mass under explosion load and its computer simulation. Methods\ Stress history is taken into account and stresses will follow changes in time during a period of explosion load. According to the principle of static force balance, the corresponding nodal concentrated force is calculated and the nodal displacement is counted. The elastic plastic dynamic finite element equations are thus obtained. Results\ A finite element method is given for a jointed rock mass under explosion load. Conclusion\ The problem of large plastic deformation for jointed rock mass on blasting was efficiently resolved through dynamic finite element analysis and the range of damages by blasting simulated, and this pushes forward the problem to engineering practice.
基金Financial supports for this work,provided by the National Natural Science Foundation of China(Nos.511204167 and 51574227)Chinese National Programs for Fundamental Research and Development(No.2013CB227905),are gratefully acknowledged
文摘A new approach named as steel pile method is innovatively proposed in this study to control severe floor heaves in gob-side entry retaining. It is required that the steel piles be installed in the floor corners with a certain interval before the influence of the dynamic pressure induced by current panel extraction. Using numerical simulation and theoretical analysis, this study investigated the interaction between the steel piles and the floor rocks during the service life of the steel piles, and revealed the mechanism of the steel piles in controlling floor heaves. The effect of the steel pile parameters on the control of floor heaves was presented and elaborated. It is found that the effectiveness of the steel piles in controlling floor heaves can be enhanced with greater installed dip angle, longer length and smaller interval of the steel piles.Compared with traditional methods, e.g., using floor anchor bolts and floor restoration, the advantages using steel pile were successfully defined in terms of controlling effect and economic benefits. It is hoped that the proposed method can contribute to the development of gob-side entry retaining technique.
基金Supported by the Yildiz Technical University Scientific Research Projects Coordination Department.Project Number:2012-10-01 KAP 02
文摘In the present study, a new approach is applied to the cavity prediction for two-dimensional （2D） hydrofoils by the potential based boundary element method （BEM）. The boundary element method is treated with the source and doublet distributions on the panel surface and cavity surface by usethe of the Dirichlet type boundary conditions. An iterative solution approach is used to determine the cavity shape on partially cavitating hydrofoils. In the case of a specified cavitation number and cavity length, the iterative solution method proceeds by addition or subtraction of a displacement thickness on the cavity surface of the hydrofoil. The appropriate cavity shape is obtained by the dynamic boundary condition of the cavity surface and the kinematic boundary condition of the whole foil surface including the cavity. For a given cavitation number the cavity length of the 2D hydrofoil is determined according to the minimum error criterion among different cavity lengths, which satisfies the dynamic boundary condition on the cavity surface. The NACA 16006, NACA 16012 and NACA 16015 hydrofoil sections are investigated for two angles of attack. The results are compared with other potential based boundary element codes, the PCPAN and a commercial CFD code （FLUENT）. Consequently, it has been shown that the results obtained from the two dimensional approach are consistent with those obtained from the others.
文摘Coal burst is a dynamic release of energy within the rock （or coal） mass leading to high velocity expulsion of the broken/failed material into mine openings. This phenomenon has been recognised as one of the most catastrophic failures associated with the coal mining industry, which can often lead to injuries and fatalities of miners as well as significant production losses. This paper aims to examine the mecha- nisms contributing to coal burst occurrence, with an emphasis on the energy release concept. In this study, a numerical modelling study has been conducted to evaluate the roles and contributions of differ- ence energy components. The energy analysis presented in this paper can help to improve the under- standing of energy release mechanisms esoeciallv under Australian conditions.
