Rib/snook design in mechanised depillaring of rectangular/square pillars

Singh, Rajendra; Kumar, Ashok; Singh, Arun Kumar; Coggan, John; Ram, Sahendra

doi:10.1016/j.ijrmms.2016.02.008

Cited by 29 publications

(8 citation statements)

References 12 publications

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“…Shapes and estimation of area of such shapes of rib/snook formed during CD and MD is shown in Figure 2. No empirical formula is applicable or available to estimate the strength of such irregular rib/snook Singh et al [4] studied the performance of rib/snook at different underground mines practising MD at different depths and nature of roof. CM carried out the slicing operation under the shadow of created competent rib/snook.…”

Section: Irregular Shaped Heightened Rib/snookmentioning

confidence: 99%

“…Some cases of burial of CM occurred at few mines due to failure of incompetent rib/ snook explained in Singh et al [2]. Singh et al [4] conducted a parametric study based on the field studies on numerical models by varying the nature of roof and depth of cover. This study found to be useful in designing a competent rib/snook during MD.…”

Section: Irregular Shaped Heightened Rib/snookmentioning

confidence: 99%

“…Parametric study by varying the nature of roof and depth of cover was carried out in FLAC 3D by Singh et al [4] to estimate the size of irregular shaped rib/snook during MD of existing square/rectangular shaped pillars. Further, height of rib was also varied [7] during extraction of complete thickness of a thick coal seam at a time using numerical simulation to estimate a stable competent size.…”

Section: Rock Mechanics Advances In Mechanised Depillaring 31 Designmentioning

confidence: 99%

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Developments Made for Mechanised Extraction of Locked-Up Coal Pillars in Indian Geomining Conditions

Kumar¹,

Kumar²,

Singh³

et al. 2021

Mining Techniques - Past, Present and Future

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Bord and Pillar method of underground mining has been used extensively to develop Indian coal seams into pillars and galleries. This results in only 20-30% recovery of coal and rest coal remain locked up in developed pillars. Indian coalfields are famous in the world for its uniqueness and complexity of the geomining conditions which makes the extraction of the locked-up coal pillars a difficult and hazardous activity using different underground mining methods. Indian mining industry has introduced mechanisation since last 10 years to deal with the various underground rock mechanics issues in order to improve the efficiency and safety during recovery of locked-up coal pillars. But mere introduction of mechanisation did not solve all the rock mechanics problems due to requirement of indigenous design of different involved geotechnical elements for Indian geomining conditions. CSIR-CIMFR is a national research organisation engaged in improving conditions of underground coal mines. It has developed rock mechanics advances, namely, design of irregular shaped heightened rib/snook, roof bolt-based breaker-line support, warning limit of roof sagging, and cutout distance for continuous miner-based mechanised depillaring. This chapter presents the developments made and highlights challenges to pursue future research studies for mechanised depillaring-based mass coal production from Indian underground mines.

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Section: Irregular Shaped Heightened Rib/snookmentioning

confidence: 99%

Section: Irregular Shaped Heightened Rib/snookmentioning

confidence: 99%

Section: Rock Mechanics Advances In Mechanised Depillaring 31 Designmentioning

confidence: 99%

See 1 more Smart Citation

Developments Made for Mechanised Extraction of Locked-Up Coal Pillars in Indian Geomining Conditions

Kumar¹,

Kumar²,

Singh³

et al. 2021

Mining Techniques - Past, Present and Future

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“…Slicing of a fender/pillar is done under the protection of rib and adjacent RBBLS against goaf. The left out ribs also work/perform like applied support for a depillaring operation [19] and its size is observed to be dependent upon nature of immediate roof strata [1]. The stable rib holds the RBBLS, which provides efficient slicing situation Considering these consequences, depth of spalling in the natural support is considered for suitable design of rib for a given site conditions.…”

Section: Strata Mechanics At Goaf Edgementioning

confidence: 99%

“…Slicing of a coal pillar/fender during the MD operation is an important mining activity, which is done under the protection of RBBLS in an opening at the goaf edge and a rib against the goaf. The RBBLS works efficiently under the shadow of stable ribs [1] and facilitates caving inside the goaf. An understanding of rib mechanics is vital for a design of the suitable RBBLS to improve efficiency of the MD operation.…”

Section: Introductionmentioning

confidence: 99%

Numerical modelling based rock load height estimation at the goaf edge in a mechanised depillaring panel

Ram¹,

Kumar²,

Rakesh³

et al. 2016

Proceedings of the Conference on Recent Advances in Rock Engineering (RARE 2016)

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Presence of different openings along the extraction line (goaf edge) in a mechanised depillaring (MD) panel provides an easy path for the goaf to encroach the working area during caving. A number of continuous miner based MD operations are adopted in Indian coalfields in last thirteen years, where roof bolt-based breaker line supports (RBBLS) is used to restrict the goaf encroachment. Different field studies by CSIR-CIMFR found that the performance of a RBBLS is significantly influenced by extension of spalling in coal pillars/fenders at the goaf edge. Development of higher induced stresses around the goaf edge during a MD operation creates the spalling in natural supports resulting a dilution in its competency at the goaf edge. It is observed that the RBBLS works satisfactorily under the shadow of stable natural supports only. Accordingly, the field studies have found that the positions of the RBBLS at the goaf edge need to be adjusted as per expected extent of the spalling. Under these conditions, estimation of rock load height (RLH) with respect to proposed position of a RBBLS at the goaf edge is a difficult task in the field. Therefore, a laboratory study, based on numerical modelling, is done using the FLAC3D package. The elastic model incorporating the Sheorey's failure criterion for the rock mass is used to analyse the rock mass behaviour at the goaf edge. Here, a criterion of 1.5 safety factor is used to obtain the RLH value. It is found that the value of RLH gets almost saturated after 2 m out-bye from the goaf edge for the considered site conditions. Therefore, an attempt is made to estimate the RLH at three positions 0 m, 1 m and 2 m out-bye from the goaf edge. This parametric study is conducted with a variation in depth of cover from 100 m to 450 m and rock mass rating from 20 to 70. This study in the laboratory supported the field observations that a RBBLS works satisfactorily under the shadow of stable natural supports. A comparison of the RLH values for different selected positions of the RBBLS provided an idea to decide its suitable position of the RBBLS for a given site conditions. Discussing important findings of the field studies, this paper presents results of the numerical modelling for estimating the RLH at the goaf edge. Strength and weaknesses of this study for the design of a RBBLS are presented on the basis of a simple analysis of the simulation results.

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