Coal Engineering ›› 2025, Vol. 57 ›› Issue (7): 136-145.doi: 10. 11799/ ce202507019

Previous Articles     Next Articles

Law of overburden migration in repeated mining of working faces in contiguous coal seams

  

  • Received:2024-07-29 Revised:2024-10-03 Online:2025-07-11 Published:2025-08-14
  • Contact: SUN Yanbin SONG HouwuPENG Xiangfeng E-mail:1134781551@qq.com

Abstract:

Abstract: Clarifying the movement laws of the overlying rock strata under repeated mining activities at extremely close range is of great significance for the stability of the mining field and the control of the surrounding rock in the return mining roadways. In the eastern mining areas, the situation of mining coal seams at close range is common, and strong mining pressure phenomena often occur in the underlying return mining roadways when the mining face is arranged in such coal seams. To further study the movement laws of the overlying rock strata under repeated mining activities at extremely close range, taking the extremely close range mining face of the Fucun Coal Mine in Zaozhuang Mining Area as the engineering background, a combination of theoretical derivation, numerical simulation, and on-site measurement was used to analyze the mining of various working faces of the 3rd upper and 3rd lower coal seams in Fucun Coal Mine and the overlying rock strata affected by repeated mining activities, as well as the state and evolutionary characteristics of the overlying rock movement. The results show that, according to the key layer theory calculation, the fracture distance of the key layer of the overlying rock of the working face is positively correlated with its distance from the top of the coal seam, and negatively correlated with the face width, and the fracture distance of the key layer decreases significantly after the second disturbance, with the percentage decrease being positively correlated with the face width. It is calculated that the height of the repeated mining fracture zone of the 1009 working face in the 3rd lower section is 94.7 m. According to the UDEC numerical simulation results, the secondary movement of the overlying rock caused by repeated mining activities greatly increases the range of the fracture zone, and the range of the fracture zone increases significantly with the increase of the working face width. It is concluded that the height of the caving zone and the fracture zone of the 1009 working face in the 3rd lower section are 32.4 m and 91.8 m, respectively. On-site measurement of the height of the two zones of the overlying rock was conducted using double-end water plugging devices, and the height of the caving zone and the fracture zone of the 1009 working face in the 3rd lower section were obtained as 41.43 m and 101.03 m, respectively, corroborating the results of theoretical derivation and numerical simulation. The research results can provide corresponding theoretical and technical basis for theoretical research and engineering construction under similar conditions.

CLC Number: