Analysis on failure characteristics of coal seam floors and water inrush risks in mining under pressure

doi:10.16265/j.cnki.issn1003-3033.2022.05.1535

Abstract

Abstract:

In order to study characteristics of floor failure under mining conditions, with working face 10409 of Xinzhi Coal Mine as a research object, distribution characteristics of floor stress field and damage evolution of floor strata were studied in detail by using a combination of theoretical analysis and numerical simulation methods. Then, based on verification results of on-site pressurized water test, distribution law of bearing pressure in coal seam floor strata and damage range of floor strata during mining process were obtained. Finally, mining risks of No. 10 coal seam under pressure was analyzed and evaluated. The results show that under influence of mining, the floor of coal seam presents periodic failure of tension failure-compaction-tension failure, and the critical value of working face length that affects failure depth of floors is about 160 m. The maximum failure depth of floor strata can reach 9.50 m, while maximum water inrush risk point lag behind working face is about 2.6 m.

Key words: pressurized coal mining, floor failure, water inrush risk, theoretical calculation, numerical simulation, pressurized water test

LI Gang, LIU Haizhen, YANG Qinghe, NIU Weifeng. Analysis on failure characteristics of coal seam floors and water inrush risks in mining under pressure[J]. China Safety Science Journal, 2022, 32(5): 68-76.

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岩层名称	体积模量/ GPa	剪切模量/ GPa	黏聚力/ MPa	内摩擦角/ (°)	抗拉强度/ MPa
细砂岩	4.8	3.1	4.2	41	1
煤层	1.9	0.95	1.2	35.1	0.429
砂质泥岩	2.2	1.152	1.5	32.5	0.586
泥岩	1.8	1.02	1.2	31.6	0.612
铝土泥岩	1.9	0.95	1.0	36	0.429
砂岩	3.5	2.12	4.3	43	1.618
页岩	1.8	0.86	1.2	37	0.303
石灰岩	5.6	3.89	5.7	42.5	0.48

孔号及特征	测试深度/m	K₁/(m·d^-1)	K₂/(m·d^-1)	K₂/ K₁	ΔK/(m·d^-1)
3号孔单栓塞压水	(7.51,12.37)	13.87	16.43	1.184 092	2.554 655
3号孔双栓塞压水	(8.98,9.03)	2.112	50.36	23.833 33	48.224
3号孔双栓塞压水	(9.45,9.50)	2.64	56.72	21.484 85	54.08
3号孔双栓塞压水	(9.96,10)	282.74	320.32	1.132 898	37.576
3号孔双栓塞压水	(10.94,11)	97.5	109.64	1.124 549	12.144

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