1、翻译部分英文原文Exploitation of developed coal mine pillars by shortwall mininga case exampleA. Kushwaha, G. BanerjeeCentral Mining Research Institute, Barwa Road, Dhanbad 826001, Jharkhand, IndiaAbstract: The shortwall mining technique is similar to longwall mining but with shorter face lengths, ranging be
2、tween 40 and 90m, with the aim of controlling 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 conducted for the longwall panel extraction
3、 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 already been developed via bord and pillar workings. In this paper, numerical modelling studies have been conducted to
4、assess the cavability of the overlying strata of the Passang seam in the mine over developed bord and 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 lengt
5、hs, strata condition and 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 shortwall mining. Keywords: Exploitation; Shortwall mining; Geo-mi
6、ning; Obliquity; Block contours; Main fall; Advance gallery1. IntroductionIn India, underground coal production is mostly dependent upon the conventional bord and pillar (room and pillar) method of mining, although the overall output per man shift (OMS) through this method is generally not more than
7、 1 ton in any of the mines 1. Large areas in all the subsidiaries of Coal India Limited 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 t
8、o 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 Passang seam in Balrampur Mine of SECL (India) over developed bord and pillar wor
9、kings along with support requirements at the face and in the advance gallery. This study is based on eld observations of a longwall panel and 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 mai
10、n fall span is predicted for varying face length, strata condition 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 miningBord and pillar mining will no
11、t be a suitable option for developed pillars at higher depth cover in terms of productivity, safety and percentage of recovery. The technology of shortwall mining overcomes most of the limitations experienced in operating longwall mining. In the Indian context, a face length of about 90m is economic
12、ally optimum with a moderately priced shearer and earning per man shift (EMS) as observed in the Indian longwall mining faces 2. Shortwall mining of the developed bord and pillar workings would be a good option to overcome the limitations of the conventional bord and pillar method of mining.3. Statu
13、s of the Passang seam of Balrampur mineThe geo-mining parameters of the proposed area of the Balrampur mine for shortwall mining panel are given below.Thickness of the seam2.4mProposed height of extraction2.4mDepth of proposed panel37-50mExisting overlying/underlying workout areasNilExisting mining
14、patternDeveloped on bord and pillar workings Pillar size20m20m(center to center)Gallery width4mVarious boreholes have been drilled over the longwall panels P-1 and P-2 of Passang seam of Balrampur mine of the same area with results as given in Table 1. The average hard cover in panels P-1 and P-2 we
15、re 29 and 39m, respectively, and the depths of the seam were 50 and 53.1m, respectively. Based on the eld observations of the caving nature of the overlying strata of the longwall panel P-1, the overlying strata have been divided into six major beds overlying the coal seam. Based on engineering judg
16、ement and giving a higher weight to the borehole lithology in panel P-1, estimated RQD and the intact average compressive and tensile strengths of different bed rocks tested in the laboratory 3 are given in Table 2. From the borehole details, it is evident that Bed-I and Bed-III are weak beds, with RQD of 40% and 43%, respectively. Bed-II and Bed-IV are relatively strong with RQD of 78% and 75%, re
