ICGCM Papers:
Roof and Rib Control Strategies
 
 
Design of Roof Bolt Based Breaker Line Support in a Mechanised Depillaring Panel
35th International Conference on Ground Control in Mining
Design of Roof Bolt Based Breaker Line Support in a Mechanised Depillaring Panel
by
Sahendra RamArun Kr Singh, Council of Scientific and Industrial Research-Central Institute of Mining and Fuel Research (CSIR-CIMFR), Dhanbad, IndiaDheeraj Kumar, Indian School of Mines, Dhanbad, IndiaRajendra Singh, Council of Scientific and Industrial Research-Central Institute of Mining and Fuel Research (CSIR-CIMFR), Dhanbad, India
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[Conference] 35th International Conference on Ground Control in Mining
[Price] Free  [Comments] 0
[Topical Area] Roof and Rib Control Strategies
[Author] Sahendra RamArun Kr Singh, Council of Scientific and Industrial Research-Central Institute of Mining and Fuel Research (CSIR-CIMFR), Dhanbad, IndiaDheeraj Kumar, Indian School of Mines, Dhanbad, IndiaRajendra Singh, Council of Scientific and Industrial Research-Central Institute of Mining and Fuel Research (CSIR-CIMFR), Dhanbad, India
[Abstract] 
Key Conclusions:
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An attempt to quantify the support density, to be provided by the RBBLS, is made on the basis of different field investigations. It is observed that the amount of encroachment by the goaf toward working area is dependent upon depth of cover and nature of overlying rock mass. A systematic study by calibrated numerical modeling provided an improved understanding of the strata dynamics around the goaf line and the influence of nature of roof strata and depth of cover on RBBLS design.
Key Findings:
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Different field studies by CSIR-CIMFR found that the RBBLS works effectively during the depillaring under the shadow of stable surrounding ribs/fenders only. It is observed that, generally, these natural supports experience high value of induced stresses after a large amount of void creation inside the goaf. The induced stress creates spalling/loosening of sides of the natural supports. Field studies also found that the positions of the RBBLS at the goaf edge need to be adjusted according to the depth of this spalling/loosening. However, a systematic study in field for the correct positioning of the breaker-line as per the spalling/loosening under different site conditions is difficult. Therefore, on the basis of the data and guidance provided by these field investigations, a detailed parametric investigation was conducted in laboratory on the simulated models for an effective design of RBBLS in a MD panel. FLAC3D is used for the simulation of the depillaring and the available empirical formulations for Indian coalfields are used for subsequent calibration. An analysis of stress redistribution for different stages of the MD in simulated models provided significance of the nature of overlying strata/induced stress for the RBBLS design. Discussing some results of field studies; this paper presents results of the laboratory investigations for an effective design of the RBBLS.
Objective of the Paper:
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To develop a design guideline for RBBLS for efficient mechanised depillaring under different geo-mining conditions. Attempts are to be made for the design of the RBBLS on the basis of the field studies and numerical simulation.
Problem Statement:
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Underground pillar extraction (depillaring) is a major issue of Indian coal mining industry because a number of upper coal seams of different coalfields are standing on pillars. These developed pillars have locked considerable amount of coal and also obstructing mining of the underlying coal seams. In a depillaring panel of the room and pillar (popular as bord and pillar in India) working, there are a number of openings along goaf line. These inherent rooms (openings) along the goaf line in a depillaring panel provide an easy path for the goaf to encroach the working area. Each of these openings in a mechanised depillaring (MD) operation, along the goaf edge, are supported by the roof bolt based breaker line support (RBBLS) to restrict the goaf encroachment. There is need to design of the applied support in opening along goaf line i.e. RBBLS as per the roof strata and depth of cover of each depillaring site.