t D W ET K E TD74 A 1000 4548(2011)11 1726 08 (1984 ) E-mail: qweiqlm@163.com Formation mechanism of dynamic impact failure zone of super dynamic water inrush in coal mine QIAO Wei 1, 2, LI Wen-ping 1, SUN Ru-hua 1, LI Xiao-qin 1, HU Ge 3 (1. School of Resources and Earth Science, China University of Mining and Technology, Xuzhou 221008, China; 2. Postdoctoral Workstation, Yankuang Group, Zoucheng 273500, China; 3. Shangdong Institute and Laboratory of Geological Sciences, Jinan 250013, China) Abstract: The elastic energy accumulates in the hard rock stratum with whole blocky structure because of underground mining. The hard rock stratum will fail with the increase of the elastic energy and instantaneously release massive energy of motion, which induces high water pressure in the aquifer near the hard rock stratum. The high water pressure creates the water-conducting which is impacted instantly between the aquifer and excavation free face so as to form the dynamic water inrush. Haizi Coal Mine is taken as a case study. The geological conditions and main factors of separation layer water are analyzed based on field investigation and numerical simulation. The burst tendency indices (Dt, W ET and K E ) of the hard rock stratum are tested. The excess hydrostatic pressure under the action of the impact dynamics is obtained by the relevant tests. Thus, the formation mechanism of dynamic impact failure zone is preliminarily studied based on the theory of blasting dynamic mechanics. Key words: mining engineering; separation layer water; dynamic water inrush; excess hydrostatic pressure; impact dynamics [1] [2] [3-6] 2005 5 21 12 13 745 5 [7] 40572160 2010 09 13
11. 1727 3887 m 3 /h 18 min 905 m 3 /h 3.5 h 139 m 3 /h 300 m 3 1 m [7-8] [7-13] 745 84 745 10 1049 0.1 m 10 2 m 0.05 m 1.6 2 m 745 # 7 85 87.6 m RQD 100% 102.30 161.91 MPa 6.78 16.94 MPa 28.64 GPa 0.17 # 7 1049 56.47 82.61 MPa 3.23 6.28 MPa 7 2.52 m 745 # 7 31.06 MPa R455 1.6 m 1.4 m 329.5 332.5 m 3 m 1 Fig. 1 Borehole televiewer photos for separation layer zone in siltstone # 7 13.3 m 332.7 346 m 5 1.74 m 342.3 m 1049 745 2 Fig. 2 Borehole televiewer photos for separation layer zone in medium-sandstone 1049 745 10 # 7 745 # 7 34 m 1049 10 # 7 745 150 m 10419 # 7 3
1728 2011 1049 Fig. 3 Overburden separation layer and major principal stress after working face No. 1049 completed 745 150 m # 7 30 31 m # 7 34 m 2 3 m 4 745 150 m Fig. 4 Overburden separation layer and major principal stress at.location of 150 m in working face No. 745 11 3 745 815.02 t D W ET K E 3 Y11 Y17 5 6 1 t D 67.38 315.43 ms W ET 3.27~10.40 K E 5.67 17.98 t D 90.86 369.629 ms W ET 2.02 5.14 K E 5.88 6.82 745 1049 Y11 t D W ET K E Fig. 5 Test curves of t D, W ET and K E for igneous rock of Y11 group
11. 1729 MTS 815.02 745 4 6 φ 30 mm φ 50 mm 20 mm φ 4 mm 7 Fig. 7 Sealed rock specimens including water MTS Pw 0.2 MPa Pw 8 Y17 t D W ET K E Fig. 6 Test curves of t D, W ET and K E for medium-sandstone of Y17 group 745 Fig. 8 Failure rock specimens 2 9 Table 1 Evalution of burst tendency for igneous rock and medium-sandstone /m t D W ET K E Y5 R456 312.70 319.30 Y6 R457 331.10 340.00 Y7 R456 355.00 365.60 Y10 R455 312.10 318.30 Y11 R455 327.10 330.20 Y13 R456 322.40 327.80 Y14 R457 410.40 412.90 Y16 R457 459.10 472.90 Y17 R459 331.20 339.30 Y18 R459 281.10 290.30 Y19 R459 304.10 310.30
1730 2011 Table 1 Test results of excess hydrostatic pressure under action of impact dynamics /s /MPa /s /MPa LR-R455-10 89.592 128.56 0.006 0.63 LR-R456-8 104.591 149.65 0.008 0.71 LR-R457-21 92.291 143.77 0.008 0.62 MS-R457-34 75.393 87.23 0.009 0.59 LR-R459-6 89.594 126.84 0.007 0.70 FS-R459-12 65.893 73.42 0.009 0.60 Fig. 9 Variation of excess hydrostatic pressure with time 2 3 m 0.6 0.7 MPa 1 # 7 2 3 m 2
11. 1731 3 4 5 10 10 a 10 b 10 c 2r b r 0 r b =0.5W max W max, 2 U = q L 5 /576EI (1) 2 L = 2 h R / q (2) 0 T 1 2 5 U = ( h /12 E) 2 R / q (3) q MN/m E MPa I I = h 3 /12 R T MPa h m T [14-15] P = B/ R α (4) P R MPa B B =72 MPa α α = 0.72 R R = R/ Q Q c TNT Q c = Q/ Q vt kg/m P 0 c α α 2 2 B Q B Q P0 = α = α (5) R QVT r0 QVT r 0 r0 rb + 0.5Wmax r b r b = L 0 /2π Q Fig. 10 Process of simplified model for formation mechanism of.dynamic impact failure zone MJ/m Q VT TNT Q VT = 4.200 MJ/kg
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