Evolution of overburden structure and stability of coal pillars in isolated island working face

doi:10.16265/j.cnki.issn1003-3033.2024.11.0682

Abstract

Abstract:

To investigate the evolution of overburden structure and the stability of district coal pillars during the mining of shallow-buried coal seam island faces, a study was conducted with the 50104 working face of Taihua coal mine as the engineering background. The research employed a combination of theoretical analysis, numerical simulation, and on-site measurement to analyze the load-bearing capacity of the district coal pillars and the characteristics of overburden structure evolution on both sides. The FLAC^3D numerical software was utilized to simulate the distribution of plastic zones and the evolution of mining-induced stress. The results indicate that during the advancement of the 50104 working face, the plastic destruction of the district coal pillars on both sides lagged behind the progress of the working face. The district coal pillars located in the goaf area behind the working face were in a state of plastic destruction, while those in front of the working face coal wall maintained a stable elastic zone, overall remaining stable. Throughout the working face advancement, the stress distribution of the district coal pillars on both sides exhibited the same characteristics, with two 11 m coal pillars showing symmetric high-stress concentration areas, both located behind the working face. The development speed of the high-stress destruction area of the district coal pillars lagged behind the advancement speed of the working face. The average stress value in the central area of the district coal pillars in front of the working face increased from 3.35 MPa to 3.54 MPa, but it never exceeded the coal pillar bearing capacity value calculated theoretically. Analysis of the mine pressure monitoring data from the 50104 working face revealed that the average initial support force was 3 932.4 kN, accounting for 55% of the rated initial support force of hydraulic support. The average maximum working resistance was 5 812.3 kN, representing 61.2% of the rated working resistance. The weighted average resistance was 4 836.6 kN per support, which is 50.9% of the rated working resistance. The maximum pressure was 6 013 kN, with a support stress of about 2.35 MPa, proving the stability of 11 m coal pillars and indicating that the overall stability of the district coal pillars in front of the working face coal wall is relatively good.

Key words: island working face, overlying rock structure, section coal pillar, pillar stability, shallow coal seam, numerical simulation

CLC Number:

X936

WANG Hongyu, CHENG Zhiheng, WANG Peng, CHEN Liang, QU Xiaoming, GUO Kai. Evolution of overburden structure and stability of coal pillars in isolated island working face[J]. China Safety Science Journal, 2024, 34(11): 108-118.

Figures/Tables 15

Fig.1

Fig.2

Fig.3

Fig.4

Fig.5

Fig.6

Fig.7

Fig.8

Table 1

Fig.9

Fig.10

Fig.11

Fig.12

Table 2

50104 working face pressure criterion

测站	支架	初撑力/kN			最大工作阻力/kN			加权平均工作阻力/kN
测站	支架	平均值 $P - 0$	均方差 S_po	判据 p'₀= $P - 0$ +S_p₀	平均值 $P - m$	均方差 $S p m$	判据 p'_m= $P - m$ + $S p m$	平均值 $P - t$	均方差 $S p t$	判据 p'_t= $P - t$ + $S p t$
上部测站	31号	4 594.7	872	5 466.7	5 920.8	423	6 343.8	5 275.8	589	5 864.8
上部测站	35号	3 611.5	729.5	4 341	5 870.1	748	6 618.1	4 941.1	939.7	5 880.8
中部测站	18号	4 718.1	716.7	5 434.8	5 808.9	436	6 244.9	4 888.9	765	5 653.8
中部测站	24号	3 824.7	1 166.2	4 990.9	5 409	1 046.3	6 455.3	4 027.3	1 173.5	5 200.8
下部测站	5号	3 468.9	628.1	4 097	5 851.7	750.5	6 602.2	4 795.6	789.2	5 584.8
下部测站	11号	3 376.5	703.8	4 080.3	6 013	496.2	6 509.2	5 090.8	930.8	6 021.6

Table 2

Fig.13

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序号	岩石名称	层厚/m	密度/(kg·m^-3)	内摩擦角/(°)	黏聚力/MPa	抗拉强度/MPa	弹性模量/GPa
1	黄土	12.00	1 700	18	0.1	0.2	1.2
2	黏土	22.00	1 800	22	0.15	0.5	1.4
3	粉砂岩	4.00	2 350	25	2.75	1.51	19.5
5	砂质泥岩	9.00	2 280	36	2.16	0.75	5.42
6	粉砂岩	10.00	2 350	25	2.75	1.51	19.5
7	细粒砂岩	6.00	2 870	42	3.42	1.29	33.1
8	中粒砂岩	19.28	2 550	37	4.0	1.20	5.99
9	5^-1煤	4.72	1 450	34	1.25	0.19	5.3
10	粉砂岩	3.00	2 350	25	2.75	1.51	19.5