Based on break characteristics of roofs in fully mechanized top-coal mining of thick shallow coal seams, a fracture mechanics model was built, and the criterion of crack propagation in the main roof was derived using ...Based on break characteristics of roofs in fully mechanized top-coal mining of thick shallow coal seams, a fracture mechanics model was built, and the criterion of crack propagation in the main roof was derived using the fracture mechanics theory. The relationships between the fracture length of the roof and the working resistance of the supports were discovered, and the correlations between the load on the overlying strata and the ratio of the crack's length to the thickness of the roof were obtained. Using a working face of Jindi Coal Mine, Xing county Shanxi province as an example, the relationships between the fracture length of the roof and the working resistance of the supports were analysed in detail. The results give a design basis in hydraulic top coal caving supports, which could provide useful references in the practical application. On-site experiment proves that the periodic weighting step interval of the caving face is 15–16 m, which is basically consistent with the theoretical analysis results, and indicates that the mechanized caving hydraulic support is capable of meeting the support requirements in the mining of a super-thick but shallowly buried coal seam.展开更多
Background of the development and achievement on sets equipment technologies for coal mine longwall face in China was reviewed initially. On the theoretical side, a coupling model of hydraulic support and surrounding ...Background of the development and achievement on sets equipment technologies for coal mine longwall face in China was reviewed initially. On the theoretical side, a coupling model of hydraulic support and surrounding rock, support pa- rameters optimization and threedimensional (3D) dynamic design method were presented. On the practical side, this paper out lined some of practical issues and discussed some relative methods and technologies. In thin seam coal longwall mining, how to lower equipment height is the first problem that should be solved. Roof pressure regularity, control of rooffall and collapse, and hydraulic support stability were investigated preferentially in 5-7 m coal seam longwall mining. The application of equip- ment for longwall mining with 5-7 m cutting height in China was concluded. The characteristics of full-mechanized top coal caving for extra thick seam coal were presented. The automation of top-caving hydraulic support and relevant equipment have achieved important breakthrough. At the end of this paper, further development of China's coal industry and longwall mining technologies and equipment were prospected in brief. This paper gives readers a comprehensive understanding of China's coal mine longwall face equipment technologies. It will give help to other countries on its coal mining development.展开更多
The structure and characteristic of new type of hydraulic support for top coal caving were discussed. The mechanism and kinematics of the hydraulic support were analyzed. The formulas were deduced to calculate the vel...The structure and characteristic of new type of hydraulic support for top coal caving were discussed. The mechanism and kinematics of the hydraulic support were analyzed. The formulas were deduced to calculate the velocity and acceleration of top beam, shield beam, front and back legs, which give the solution to the design and research for hydraulic support.展开更多
It is showed in practice that the support load and its fluctuation is large, the periodic weighting is obvious and can be divided into two kinds, the large and small pressure, sometimes the behavior of the large press...It is showed in practice that the support load and its fluctuation is large, the periodic weighting is obvious and can be divided into two kinds, the large and small pressure, sometimes the behavior of the large pressure is very violent in hard thick seam caving faces. These are obviously different from those of the generally soft or medium hard seam caving feces. All above these are summarized, and the causes aroused these are researched. Finally the powered support selection of hard thick seam caving faces is discussed.展开更多
文摘Based on break characteristics of roofs in fully mechanized top-coal mining of thick shallow coal seams, a fracture mechanics model was built, and the criterion of crack propagation in the main roof was derived using the fracture mechanics theory. The relationships between the fracture length of the roof and the working resistance of the supports were discovered, and the correlations between the load on the overlying strata and the ratio of the crack's length to the thickness of the roof were obtained. Using a working face of Jindi Coal Mine, Xing county Shanxi province as an example, the relationships between the fracture length of the roof and the working resistance of the supports were analysed in detail. The results give a design basis in hydraulic top coal caving supports, which could provide useful references in the practical application. On-site experiment proves that the periodic weighting step interval of the caving face is 15–16 m, which is basically consistent with the theoretical analysis results, and indicates that the mechanized caving hydraulic support is capable of meeting the support requirements in the mining of a super-thick but shallowly buried coal seam.
文摘Background of the development and achievement on sets equipment technologies for coal mine longwall face in China was reviewed initially. On the theoretical side, a coupling model of hydraulic support and surrounding rock, support pa- rameters optimization and threedimensional (3D) dynamic design method were presented. On the practical side, this paper out lined some of practical issues and discussed some relative methods and technologies. In thin seam coal longwall mining, how to lower equipment height is the first problem that should be solved. Roof pressure regularity, control of rooffall and collapse, and hydraulic support stability were investigated preferentially in 5-7 m coal seam longwall mining. The application of equip- ment for longwall mining with 5-7 m cutting height in China was concluded. The characteristics of full-mechanized top coal caving for extra thick seam coal were presented. The automation of top-caving hydraulic support and relevant equipment have achieved important breakthrough. At the end of this paper, further development of China's coal industry and longwall mining technologies and equipment were prospected in brief. This paper gives readers a comprehensive understanding of China's coal mine longwall face equipment technologies. It will give help to other countries on its coal mining development.
文摘The structure and characteristic of new type of hydraulic support for top coal caving were discussed. The mechanism and kinematics of the hydraulic support were analyzed. The formulas were deduced to calculate the velocity and acceleration of top beam, shield beam, front and back legs, which give the solution to the design and research for hydraulic support.
文摘It is showed in practice that the support load and its fluctuation is large, the periodic weighting is obvious and can be divided into two kinds, the large and small pressure, sometimes the behavior of the large pressure is very violent in hard thick seam caving faces. These are obviously different from those of the generally soft or medium hard seam caving feces. All above these are summarized, and the causes aroused these are researched. Finally the powered support selection of hard thick seam caving faces is discussed.