Ground movement mechanism in tectonic stress metal mines with steep structure planes

Abstract

When mining metal mines with steep structure planes by the caving method, there is a mechanical model in which the horizontal stress on the rock mass is simplified as a column before surface subsidence. The model is used to deduce critical support load and limiting column length for a given horizontal stress and support pressure. Considering the impact of the column effect, a method is proposed to determine the movement of the ground and caving area in a mine. After surface subsidence, the horizontal stress on a surrounding rock mass can be simplified to a cantilever beam mechanical model. Expressions for its bending fracture length are deduced, and a method is given to determine its stability. On this basis, an explanation for the large ground movement and subsidence scope was given. A case study shows that the damage effect of column and cantilever beam is significant for ground movement in metal-ore mine, and an appropriate correction value should be applied when designing for its angle of ground movements.

Keywords

mining engineering / underground mining / ground movement / horizontal stress / column / cantilever pillar

References

[1] QianM-g, ShiP-w, XuJ-linMine pressure and strata control [M], 2010, Xuzhou, China Mining University Press

[2] BradyB H G, BrownE TRock mechanics for underground mining [D], 1985, London, George Allen Unwin

[3] ChengG-w, ChenC-x, ShenQian. The mechanism of rock movement caused by underground mining in Chengchao Iron [J]. Rock and Soil Mechanics, 2014, 35(5): 1421-1429

[4] CaiM-fengDesign and optimization of metal mine mining design and ground pressure control [M], 2000, Beijing, Science Press

[5] HathewayA W. Subsidence at san manuel copper mine, pinal country, Arizona [J]. Engineering Geology Case Histories, Geol Soc Am, 1968, 6: 65-81

[6] HoekE. Progressive caving induced by mining an inclined ore body [J]. Bulletin and Transactions of the Institution of Mining and Metallurgy, 1974, 83: 133-139

[7] BROWN E T. Block caving geomechanics [D]. Australia: Julius Kruttschnitt Mineral Centre, 2003.

[8] LiL C, TangC A, ZhaoX D, CaiM. Block caving-induced strata movement and associated surface subsidence: a numerical study based on a demonstration model [J]. Bulletin of Engineering Geology and the Environment, 2014, 73(4): 1165-1182

[9] HeY-guangModelling and monitoring Ground movement due to excavation [D], 2003, Changsha, Central South University

[10] FangJ-q, PengZ-b, YanR-gui. The law of tectonic stress mining ground surface subsidence and its engineering treatment method [J]. Journal of Central South University of Technology: Natural Science, 2004, 35(3): 506-510

[11] HebblewhiteB KRegional horizontal movements associated with longwall mining [R], 2001, Sydney, University of New South Wales Mining Research Centre

[12] LiW-x, WenL, LiuX-ming. Regional horizontal displacements and its effect on shaft in mining areas [J]. Chinese Journal of Rock Mechanics and Engineering, 2009, 28(S2): 3926-3931

[13] XiaK-z, LiuX-m, ChenC-x, FuH, ZhangH-n, ZhangJ-j, WuY-mei. Study on ground deformation caused by underground mining in western area of Chenchao iron mine [J]. Chinese Journal of Rock Mechanics and Engineering, 2014, 33(8): 1572-1588

[14] ZhaoK, ChenS-ni. Study on artificial neural network method for ground subsidence prediction of metal mine [J]. Environmental Earth Sciences, 2011, 2: 177-182

[15] LiuQ, LiuZ-x, LiD-y, LiWei. Knowledge bank model to predict motion angle of terrane in metal deposit and its application in engineering [J]. Journal of Central South University: Science and Technology, 2011, 42(8): 2446-2452

[16] AlehosseinH, PoulsenB A. Stress analysis of longwall top coal caving [J]. International Journal of Rock Mechanics and Mining Sciences, 2009, 47(1): 30-41

[17] LiC-leiStudy on mechanism and prediction of ground subsidence in mines using caving technique [D], 2007, Beijing, University of Science & Technology Beijing

[18] LiuC-h, ChenC-xinStratified rock slope stability [M], 2012, Wuhan, Science Press

[19] SunX-f, FangX-s, GuanL-taiMechanics of materials [M], 2009, Beijing, Higher Education Press

[20] XiaoYuan. The problem of critical load of layered rock mass under axial and lateral force [C]// WEI Qun. Rock Mechanics Problems in Hydropower and Mining Engineering-Chinese Northern Rock Mechanics and Engineering Conference. Beijing: Science Press, 1991276281

[21] AydanO, KawamotaT. Toppling failure of discontinuous rock slopes and their stabilization [J]. Journal of the Mining and Metallurgical Institute of Japan, 1987, 103: 763-770

[22] AydanO, KawamotoT. The stability of slopes and underground openings against flexural toppling and their stabilization [J]. Rock Mechanics and Rock Engineering, 1992, 25(3): 143-165

[23] AdhikaryD P, DyskinA V, JewellR J, StewartD P. A study of the mechanism of flexural toppling failure of rock slopes [J]. Rock Mechanics and Rock Engineering, 1997, 30(2): 75-93

[24] AdhikaryD P, DyskinA V, JewellR J. Modelling of flexural toppling failures of rock slopes [C]// Proceedings of the 8th International Congress on Rock Mechanics. Tokyo, Japan, 19952529

[25] AdhikaryD P, DyskinA V. Modelling of progressive and instantaneous failures of foliated rock slopes [J]. Rock Mechanics and Rock Engineering, 2007, 40(4): 349-362

[26] XiaK-z, ChenC-x, FuH, ZhengY, DengY-yang. Analysis of the law of ground deformation induced by caving mining in metal mines [J]. Rock and Soil Mechanics, 2016, 37(5): 1434-1440