Numerical modelling based assessment of setting load requirement for optimum performance of powered roof supports in longwall workings

Abstract

The influence of setting load for effective strata control at a longwall face is highly debated. Field observations conducted by researchers worldwide suggest a large range of setting load variation from 30 to 80% of yield load of support. The exact quantification of optimum setting load for a given strata condition has not been possible with the existing methodologies. This paper describes the results of a numerical modelling study to assess the optimum setting load requirement in longwall workings. The study suggests that the criteria for selection of the optimal setting load should be based on peak roof convergence at the face so that there is no significant deterioration of roof causing any practical difficulty in smooth face advance during periodic weighting at the face. This is a prerequisite condition for maintaining an efficient strata control during progressive face advance for safety and sustainability of the longwall face operation.

Keywords

LONGWALL STRATA CONTROL SUPPORT PERFORMANCE SETTING LOAD ABUTMENT ROOF CONVERGENCE CAVING BEHAVIOUR

Get full access to this article

View all access options for this article.

References

Barczak

T. M.

and Oyler

D. C.

: ‘A model of shield strata interaction and its implications for active shield setting requirements’, US Department of Interior, Bureau of Mines, RI 9394, 1999.

Mishra

B. C.

: ‘Current trends in selection of roof supports – a review’, Minetech, 1984, 5, (4), 53–58.

Schaller

and Richmond

: ‘Longwall mining in Australia’, J. Mines, Met. Fuels, September, Special Number on Update on Longwall Mining – Evolving Trends, 1983, 345–355, 362.

Gupta

R. N.

: ‘The influence of setting pressure on support performance and strata behaviour on longwall faces’, PhD thesis, University of Newcastle upon Tyne, UK, 1982.

Gupta

R. N.

and Farmer

I. W.

: ‘Interaction between roof and support on longwall faces with particular reference to support resistance’, Proc. 4th Conf. on ‘Ground control in mining’, Morgantown, WV, USA, July 1985, West Virginia University, 58–77.

Martin

, Carr

and Hendon

: ‘Strata control advances at Jim Walter Resources, Mining Division’, Proc. 7th Int. Conf. on ‘Ground control in mining’, Morgantown, WV, USA, August 1988, West Virginia University, 66–75.

Barczak

T. M.

: ‘Selecting the right shield support’, Eng. Min. J., 1990, May, 36–43.

Aziz

N. I.

and Porter

: ‘Strata control investigations at a 2·7 m high longwall face using 4/900 tonnes chock shield supports’, Proc. Int. Symp. on ‘Mining technology and science’, Xuzhou, China, September 1985, China Institute of Mining and Technology, 16–26.

Sarkar

S. K.

and Dhar

B. B.

: ‘Strata control failures at caved longwall faces in India – experience from Rana to Churcha (1964 to 1990)’, Proc. 4th Asian Mining, Calcutta, India, November 1993, MGMI, 361–380.

10.

Singh

G. S. P.

: ‘Cavability assessment and support load estimation for longwall workings in India’, PhD thesis, Department of Mining Engineering, Indian School of Mines University, Dhanbad, India, 2007.

11.

Itasca: FLAC Version 4.0 User's Manual, Itasca Consulting Group, Inc., Minneapolis, MN, USA, 2000.

12.

Singh

G. S. P.

, Singh

U. K.

and Banerjee

: ‘Cavability assessment model for longwall working in India’, Proc. 3rd Asian Rock Mechanics Symp., Kyoto, Japan, November 2004, ISRM, 295–300.

13.

Sheorey

P. R.

: ‘A theory for in situ stresses in isotropic and transversely isotropic rock’, Int. J. Rock Mech. Min. Sci. Geomech. Abstr., 1994, 31, 23–34.

14.

Singh

G. S. P.

and Singh

U. K.

: ‘Numerical modelling study of strata and support behaviour in thick seam longwall workings’, Min. Technol., (Trans. Inst. Min. Metall. A), 2009, 117, (4), 191–201.

15.

Barczak

T. M.

: ‘State of the art testing and analysis of mine roof support systems’, Eastern Coal Mine Geo – mechanics: Proc. Bureau of Mines Technol. Transfer Semin., Pittsburgh, PA, USA, November 1986, US Department of Interior, Bureau of Mines, IC. 9137.