案例分析—用短壁開采的方式來回收煤柱畢業(yè)論文外文翻譯

1、中文 中文 6660 字出處： 出處： International journal of rock mechanics and mining sciences, 2005, 42(1): 127-136英文原文Exploitation of developed coal mine pillars by shortwall mining—a case exampleA. Kushwaha, G. BanerjeeCentral Minin

2、g Research Institute, Barwa Road, Dhanbad 826001, Jharkhand, IndiaAbstract: The shortwall mining technique is similar to longwall mining but with shorter face lengths, ranging between 40 and 90m, with the aim of controll

3、ing the caving nature of the overlying upper strata, the load on support and the overall operation of the supports applied at the face. Field observations and three-dimensional numerical modelling studies have been condu

4、cted for the longwall panel extraction of the Passang seam at Balrampur Mine of SECL to understand the caving behavior of the overlying upper strata. A large area of the Passang seam adjacent to the longwall panels has a

5、lready been developed via bord and pillar workings. In this paper, numerical modelling studies have been conducted to assess the cavability of the overlying strata of the Passang seam in the mine over developed bord and

6、pillar workings along with the support requirement at the face and in the advance gallery. The caving nature of the overlying rocks characterized by the main fall is predicted for varying face lengths, strata condition a

7、nd depths of cover. The support resistance required at the face, the load in the advance gallery and its optimal obliquity were estimated for faster exploitation of the developed pillars in the Balrampur mine by shortwal

8、l mining.Keywords: Exploitation; Shortwall mining; Geo-mining; Obliquity; Block contours; Main fall; Advance gallery1. IntroductionIn India, underground coal production is mostly dependent upon the conventional bord and

9、pillar (room and pillar) method of mining, although the overall output per man shift (OMS) through this method is generally not more than 1 ton in any of the mines [1]. Large areas in all the subsidiaries of Coal India L

10、imited and even in Singarani Coal Companies Limited (India) have been developed via bord and pillar workings. There is a need to search for a new method of mining for the faster exploitation of these developed pillars to

11、 improve productivity.In this paper, the authors have conducted different numerical modelling studies using Fast Lagrangian Analysis of Continua (FLAC) software, to assess the cavability of the overlying strata of the Pa

12、ssang seam in Balrampur Mine of SECL (India) over developed bord and pillar workings along with support requirements at the face and in the advance gallery. This study is based on field observations of a longwall panel a

13、nd laboratory tested data of the overlying roof rocks as the input parameter for the modelling. The caving nature of the overlying rocks characterized by the main fall span is predicted for varying face length, strata co

14、ndition and depth of cover. Further, optimal obliquity of the face was also estimated for faster and safe exploitation of the developed pillars by shortwall mining to improve the productivity.2. Shortwall miningLongwall

15、panel P-1 with a face length of 156m, situated at an average depth cover of 50m at the Balrampur mine was extracted with the help of the first Chinese powered support in 1998. In this panel, local falls had started takin

16、g place at regular intervals after a face advance of 25m, involving the immediate roof fall of around 5m height, filling approximately 60% of the void in the goaf. On 26th May, 1998, when the face advance was 67m, a fall

17、 of considerable extent was observed. It appeared to be the main fall but no subsidence was recorded at the surface. Later, the main fall took place on 28th May 1998 at a distance of 79–80m from the barrier. This loading

18、 caused extensive damage to the powered supports installed at the face and subsidence was observed on the surface. This was recorded as the first main fall.Table 2 Representative lithology above the Passang seam, plus th

19、eir intact propertiesBed No.Run up wards(m) Rock types Thickness(m)RQD( %)Compressive strength (MPa)Tensile strength (MPa)Bed-Ⅰ 0.5-5.51Coal Medium grained sandstone, laminated with shale2.4 5.51- 4023.8 10.962.5 1

20、.5Bed-Ⅱ 5.51-12.17Coarse grained to medium grained sandstone6.66 78 17.1 1.4Bed-Ⅲ 12.17-16.02 Very coarse grained sand stone 3.85 43 13.92 1.4Bed-Ⅳ 16.02-30.00 Medium grained sand stone 13.98 75 14.5 2.2Bed-Ⅳ 30.00-4

21、1.00 Weathered rock 11.00 - - -Bed-Ⅵ 41.00-50.00 Sandy soil 9.00 - - -5. Cavability analyses of the overlying strataNumerical modelling for shortwall mining of devel-oped bord and pillar workings was conducted using FLAC

22、 3D software with the tested and calibrated rock mass properties. This model study was undertaken with a face length equivalent to four pillars (84m) and five pillars (104m) wide, along with variation in depth and hard c

23、over, to understand the cavability of the roof strata. The main fall position during the shortwall mining with varying face length and depth of cover was predicted. The following geometry was modelled:Average thickness o

24、f seam 2.4mDepth of cover 50 and 40mHard cover/Alluvial soil for 50m depth cover 30m/20mHard cover/Alluvial soil for 40m depth cover 20m/20m and 30m/10mPillar size (Center-to-Center) 20m×20mWidth of gallery 4mFace l

25、ength 84m/104mIn the absence of the in situ measurements of stress values, theoretical values were calculated using the following equation:(1) ) 1000 ( ) 1 ( 1 ? ? ? ? ? H EGv h ?? ? ?? ?where and are the vertical and ho