A proper understanding of the influence of strata characteristics on progressive caving behaviour and support performance is essential for reliable planning, rational support selection and safe operation of longwall faces. This paper reports numerical modelling results to explain the influence of roof characteristics on strata behaviour and adequacy of support during face advance in three different conditions. The study reveals that although the field support of a given capacity was adequate to work bottom section under general roof formation, it needed to be used in conjunction with a rapid yield valve (RYV) having a peak discharge capacity of 470 L min−1 and a response time of 52 ms for safe extraction of top section working. A safe and smooth extraction of the bottom section longwall panels under hard roof formation required higher capacity support in conjunction with an RYV for safe management of en masse caving under prevailing strata conditions.
BarczakTM. 1989. Safety evaluation of longwall roof supports, United States Bureau of Mines, IC 9221, Pittsburgh Research Centre, Pittsburgh, PA, USA.
2.
BarczakTM, SchwemmerDE. 1988. Stiffness characteristics of longwall shields, US Department of Interior, Bureau of Mines, RI 9154, Pittsburgh Research Centre, Pittsburgh, PA, USA.
3.
BinnsPD. 1975. Face supports – how strong, how heavy (1)– the case of existing British designs, Colliery Guard., Annu. Rev., August, 295–301.
BudirskyS.1985. Interaction of powered supports and the strata in coal seams under a heavy roof, Int. J. Min. Eng., 3, 113–138.
6.
EvansI.1975. Face support requirements: a problem in arching, NCB MRDE Report No. 64, Burton on Trent, UK.
7.
FarmerI, GuptaRN. 1993, 1994. Geotechnical design aspects of longwall caving in difficult conditions, J. Min. Res., 2, (3–4), 25–32.
8.
GoshtasbiK, OraeeK, Hhakpour-yeganehF.2006. Shield support selection based on geometric characteristics of coal seam, J. Min. Sci., 42, (2), 151–156.
9.
HebblewhiteB, SimpsonJ.2001. Wider longwall faces may not be better, Min. Technol: Trans. Inst. Min. Metall., Section A, 110, (1), 11–17.
10.
Itasca. 2000. FLAC Version 4.0 User's Manual, Itasca Consulting Group, Inc., Minneapolis, MN, USA.
11.
JianW.1985. Effects of horizontal thrust on shield longwall face strata control, Proc. Int. Symp. on ‘Mining technology and science’, 47–54, Beijing, China Coal Industry Publishing House, Transtech Publications.
12.
JosienJP, GouillouxC.1978. Present and future roof control and support in longwall faces in French coal mines, Colliery Guard., 226, 49–58.
13.
KellyM.2000. 3D aspects of longwall geomechanics, Aust. Coal Rev., April, 20–25.
14.
KellyM, GaleW, HatherlyP, BalusuR, LuoX.1998. Combining modern assessment methods to improve understanding of longwall geomechanics, Proc. Coal Operators Conf., Wollongong, Australia, February, University of Wollongong, 523–535.
15.
MatthewsJ.1986. Specifying and acquiring longwall shield supports, Proc. 27th US Symp. on ‘Rock mechanics’, Tuscaloosa, AL, USA, June, Society of Mining Engineers, University of Alabama, no. 86–0360.
16.
MitraR, WestmanEC, MrugalaMJ. 2004. Use of numerical modelling in longwall roof performance analysis, Proc. 6th North America Rock Mechanics Symposium (NARMS): rock mechanics across borders and discipline, Houston, TX, USA, June, American Rock Mechanics Association, Paper no. ARMA/NARMS/04-518.
17.
OzelR, UnalE.1998. Support and strata interaction in longwall faces, Int. J. Rock Mech. Min. Sci., 35, (4/5), 484–485.
18.
QianM-G. 1982. A study of the behaviour of overlying strata in longwall mining and its application to strata control, Proc. Symp. on ‘Strata mechanics’, Newcastle upon Tyne, Elsevier Scientific Publishing Company.
19.
SarkarSK. 1998. Mechanised longwall mining – the Indian experiences, New Delhi, Oxford& IBH Publishing Company Private Limited.
20.
SarkarSK, ChatterjeeTK, SinghSK. 1995. Characterization of Indian coal measures and some aspects of their typical behaviour, Proc. 1st Natl Conf. on ‘Ground control in mining, Calcutta, India, January, 3–19.
21.
SinghGSP, SinghUK. 2008. Numerical modelling study of strata and support behaviour in thick seam longwall workings, Min. Technol: Trans. Inst. Min. Metall., Section A, 117, (4), 191–201.
22.
SinghGSP, SinghUK. 2009a. A numerical modelling approach for assessment of progressive caving of strata and performance of hydraulic powered support in longwall workings, Comput. Geotech., 36, 1142–1156.
23.
SinghGSP, SinghUK. 2009b. Assessment of support capacity requirement for longwall working under difficult caving strata conditions, Proc. Int. Symp. on ‘Rock mechanics: rock characterization, modelling and engineering design methods’, Hong Kong, China, May, The University of Hong Kong, 873–877.
24.
SinghGSP, SinghUK. 2009c. Numerical modelling based assessment of setting load requirement for optimum performance of powered roof supports in longwall workings, Min. Technol: Trans. Inst. Min. Metall., Section A, 118, (2), 109–114.
25.
SinghGSP, SinghUK. 2009d. Numerical modelling study of the effect of some critical parameters on caving behaviour of strata and support performance in a longwall working, Rock Mech. Rock Eng., 43, (4), 475–489.
26.
SinghGSP, SinghUK. 2009e. Assessment of dynamic loading and rapid yield valve requirement for powered roof supports in longwall workings, Min. Technol: Trans. Inst. Min. Metall., Section A, 118, (1), 47–52.
27.
SinghGSP, SinghUK. 2010. Prediction of caving behaviour of strata and optimum rating of hydraulic powered support for longwall workings, Int. J. Rock Mech. Min. Sci., 47, 1–16.
28.
SinhaBK, GuptaML. 2008. Development of longwall technology in India – need of the hour, J. Ind. Inst. Coal Manage., December, 7–10.
29.
SmartBGD, AzizNI. 1986. The influence of caving in the Hirst and Bulli seams on powered support rating, Proc. Symp. on ‘Ground movement and control related to coal mining’, 1–12, Wollongong, The Australian Institute of Mining and Metallurgy.
30.
SmartBGD, RedfernA.1986. The evaluation of powered support specification from geological and mining practice information, Proc. Rock Mechanics: Key to Energy Production: 27th US Symp. on ‘Rock mechanics’, Tuscaloosa, AL, USA, June, The University of Alabama, 367–377.
31.
SmartBGD, SommervilleJM, McGrawWM. 1987. Instrumentation for monitoring powered support behaviour, Min. Sci. Technol., 5, 153–161.
32.
TruemanR, LymanG, CockerA.2009. Longwall roof control through a fundamental understanding of shield-strata interaction, Int. J. Rock Mech. Min. Sci., 46, 371–380.
33.
VervoortA.1988. Influence of longwall support on the occurrence of roof cavities, Int. J. Min. Geol. Eng., 6, 313–326.
34.
WilsonAK. 1983. The stability of underground workings in the soft rocks of the coal measures, Int. J. Min. Eng., 1, 91–187.
ZhuD, QianM, PengSS. 1989. A study of displacement field of main roof in longwall mining and its application, Proc. 30th US Symp. on ‘Rock mechanics’, 149–156, Rotterdam, A. A. Balkema.
