1、Study on mining the protective seam with the manless working face in coal and gas outburst minesFang Xin-qiua,b, Zhao Jun-jiea,b, He Jiea,b, aSchool of Mines, China University of Mining & Technology, Xuzhou 221116, China bState Key Laboratory of Coal Resources and Safety Mine, Xuzhou 221008, ChinaAb
2、stract: In order to solve the problems of backward equipments, low recovery, security issues, high mortality in the coal industry, the technology of manless working face in mine which combined the traditional mining process with the automatic technology is proposed based on the scientized mining, me
3、anwhile, the idea of exploiting the protective seam in the coal seam group of the coal and gas outburst mines with manless working face technology is also proposed so as to liberate other high gas coal seams. Then, making the third coal seam in Shaqu coal mine which is a coal and gas outburst mine a
4、s the protective seam was being exploited and carried out the designs which included roadway, equipments selection and mining process. Finally, based on the theoretical analysis and numerical simulation, the gas extraction arrangements is designed, which provides the scientific basis and method for
5、industrial experiment of the third coal seam.Key words: scientized mining; coal seam group; protective seam; manless working face; gas extraction1. IntroductionThe scientized mining means mining the coal with the highest efficiency on the precondition of safety and environment friendly 1. Chinas coa
6、l output is very big, the advanced mining machines must be used in order to adapt to the construction of modern mine, furthermore, the manless working face should also be used in some difficult conditions such as thin coal seam or coal and gas outburst seam. Although the mining technology develops r
7、apidly, the overall level is still relatively backward. In order to solve this problem, change the present situation and keep the sustainable development of coal resources 2, the author proposes that the protective seam is mined with the manless working face in the coal and gas outburst mines. Then
8、other high-gas coal seams can be liberated and the gas concentration can also be decreased, so there will be a safe condition for mining. Finally, the safe and high efficient green mining will be achieved 3.2. Mining the protective seam in high outburst minesThe coal seam group is one character of t
9、he high gas mining area in china and the permeability of coal seam is very low 4. Therefore, gas is the primary factor which prevents this kind of mines from safety and high efficiency.The protective seam mining is widely used in these high outburst mines in China so as to solve this problem. In add
10、ition, this is the most scientific method to prevent the regional gas outburst under the condition of mining the coal seam group in high outburst mines 5, 6.When there is a coal seam group in the gas outburst mine, the no-outburst seam or little-outburst seam will be firstly exploited, and this kind
11、 of coal seam is called the protective seam. The original equilibrium state of stress will be broken after the protective seam is exploited. Besides, with the development of roof and floor, the strata stress will be redistributed. The roof strata can be divided into caving zone, fractured zone, and
12、bending zone 7, the floor strata will generate floor heave and fractures 8. The fractures contain bedding joint and cross-fracture, the degree of the fracture development of the floor is in inverse proportion to the spacing of layers. The methods of gas extraction can be classified as short distance, medium distance and long distance through the relative spacing of layers which is based on the concrete geological conditions of the coal mines 9, which provides a theoretical guidance to the gas control of coal seamgroup.
