OJG  Vol.4 No.12 , December 2014
A Simulation Study of Support Break-Off and Water Inrush during Mining under the High Confined and Thick Unconsolidated Aquifer
ABSTRACT
The thick Cenozoic unconsolidated aquifer is deposited under Sunan syncline core in Huaibei coalfield, the water yield property of unconsolidated bottom aquifer is strong and water pressure is high in some areas (up to 4 MPa in some areas). Water inrush accident often occurs during mining under unconsolidated aquifer, the biggest characteristic is abnormal mine pressure and support break-off during water inrush accident comparing with normal condition. In order to study mechanism of support break-off and water inrush during mining under the high confined thick unconsolidated aquifer, a simulation of similar material was designed. The experimental results indicated that, under normal condition, the compound breakage sequence of water-resisting key strata between coal seam and high confined thick unconsolidated aquifer is from top to bottom and the basic reason of synchronous fracture is the load of bottom key strata increased suddenly when the breakage of top key strata happened. Because of high confined thick unconsolidated aquifer, surface acts on the bottom key strata soil layer in the form of uniformly distributed load, which is the load-transfer mechanism of confined thick unconsolidated aquifer. Once the overlying key strata compound breaks, the height of unstable strata will reach far more than 30 meters and exceed support capability of current fully-mechanized mining supporter, which leads to support break-off accident during mining process under confined unconsolidated aquifer.

Cite this paper
Liu, Y. , Liu, Q. , Jin, Z. , Cai, L. and Cui, X. (2014) A Simulation Study of Support Break-Off and Water Inrush during Mining under the High Confined and Thick Unconsolidated Aquifer. Open Journal of Geology, 4, 599-611. doi: 10.4236/ojg.2014.412044.
References
[1]   Xu, J.L., Wang, X.Z., Liu, W.T., et al. (2009) Effects of Primary Key Stratum Location on Height of Water Flowing Fracture Zone. Chinese Journal of Rock Mechanics and Engineering, 28, 380-385.

[2]   Hang, Y., Zhang, G.L. and Yang, G.Y. (2009) Numerical Simulation of Dewatering Thick Unconsolidated Aquifers for Safety of Underground Coal Mining. Mining Science and Technology (China), 19, 312-316. http://dx.doi.org/10.1016/S1674-5264(09)60058-2

[3]   Paradis, D. and Lefebvre, R. (2013) Single-Well Interference Slug Tests to Assess the Vertical Hydraulic Conductivity of Unconsolidated Aquifers. Journal of Hydrology, 478, 102-118.
http://dx.doi.org/10.1016/j.jhydrol.2012.11.047

[4]   Sui, W.T., Cai, G.T. and Dong, Q.H. (2007) Experimental Research on Critical Percolation Gradient of Quicksand across Overburden Fissures Due to Coal Mining Near Unconsolidated Soil Layers. Chinese Journal of Rock Mechanics and Engineering, 26, 2084-2091.

[5]   Xu, J.L., Cai, D. and Fu, K.L. (2007) Mechanism of Supports Crushing Accident and Its Preventive Measures during Coal Mining near Unconsolidated Confined Aquifer. Journal of China Coal Society, 32, 1239-1243.

[6]   Tan, S.Y. and Wu, J.S. (2006) Cause Analysis of Water Bursting in 7114 Mining Face of 71 Coal Seam in Qidong Colliery. Journal of Coal Mining Technology, 11, 64-67.

[7]   Xiong, X.Y. and Li, J.B. (2004) A Case Study of Support Break-Off at 1402(3) Fully Mechanized Mining Face. Coal Geology of China, 16, 34-37.

[8]   State Coal Industry (1984) Mine Hydro-Geological Point of Order. Coal Industry Press, Beijing. (In Chinese)

[9]   Xu, J.L. and Qian, M.G. (2000) Method to Distinguish Key Strata in Overburden Strata. Journal of China University of Mining and Technology, 29, 463-467.

[10]   Lu, H.F., Yuan, B.Y. and Wang, L. (2011) Rock Parameters Inversion for Estimating the Maximum Heights of Two Failure Zones in Overburden Strata of a Coal Seam. Mining Science and Technology (China), 21, 41-47.

[11]   Li, J.K., Wang, J.A. and Cui, S.H. (2005) Study on Pump Excavation Deformation and Fracture with Complex Stress under Deep Mining and High Pressure. Ground Pressure and Strata Control, 22, 12-13. (In Chinese)

[12]   Xiao, T.Q., Wang, X.Y. and Zhang, Z.G. (2014) Stability Control of Surrounding Rocks for a Coal Roadway in a Deep Tectonic Region. International Journal of Mining Science and Technology, 24, 171-176. http://dx.doi.org/10.1016/j.ijmst.2014.01.005

[13]   Guo, G.L., Zha, J.F., Miao, X.X., Wang, Q. and Zhang, X.N. (2009) Similar Material and Numerical Simulation of Strata Movement Laws with Long Wall Fully Mechanized Gangue Backfilling. Procedia Earth and Planetary Science, 1, 1089-1094. http://dx.doi.org/10.1016/j.proeps.2009.09.167

[14]   Lu, A.H., Mao, X.B. and Liu, H.S. (2008) Physical Simulation of Rock Burst Induced by Stress Waves. Journal of China University of Mining and Technology, 18, 401-405. http://dx.doi.org/10.1016/S1006-1266(08)60084-X

[15]   Li, Y.J., et al. (2014) A Physical and Numerical Investigation of the Failure Mechanism of Weak Rocks Surrounding Tunnels. Computers and Geotechnics, 61, 292-307.
http://dx.doi.org/10.1016/j.compgeo.2014.05.017

[16]   Bieniawski, Z.T. (1989) Rock Mass Classifications in Rock Engineering. John Wiley & Sons, Inc, Hoboken.

[17]   Xiao, T.Q., et al. (2011) Characteristics of Stress Distribution in Floor Strata and Control of Roadway Stability under Coal Pillars. Mining Science and Technology (China), 21, 243-247.
http://dx.doi.org/10.1016/j.mstc.2011.02.016

[18]   Liu, C.R. (2011) Distribution Laws of In-Situ Stress in Deep Underground Coal Mines. Procedia Engineering, 26, 909-917. http://dx.doi.org/10.1016/j.proeng.2011.11.2255

 
 
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