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Coal Engineering ›› 2023, Vol. 55 ›› Issue (11): 95-101.doi: 10.11799/ce202311016

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Coupling mechanism between shields and roof strata in fully mechanized caving face and its influence on stability of face-to-tip roof

  

  • Received:2023-02-27 Revised:2023-05-26 Online:2023-11-20 Published:2025-04-07

Abstract:

A good interaction between shields and roof strata is beneficial to the control of surrounding rocks in the open face area and the prevention of face-to-tip roof fall in fully mechanized caving face. In this paper, the finite element limit analysis and physical simulation are used to study the influence of the inclination of the shield canopy, the face-to-tip distance, the coal cutting height and the overlying rock rotation on the stability of the face-end roof and the interaction between the supports and surrounding rocks. The displacement development of the top coal both above the canopy and along the face-to-tip distance, the load condition of the support, the roof caving characteristics and the evolution of the face-end caving are obtained. The results show that: (1) the vertical displacement of top coal above the canopy presents the characteristics of "large in the middle and small at both ends". The horizontal displacement increases gradually from the canopy tip to the goaf direction, while the topcoal displacement in the non-support zone in the face-to-tip area decreases from the coal wall side to the canopy tip. (2) When the inclination of the canopy is 3° downward, the support can provide horizontal resistance to the top coal. The displacement of the top coal above the canopy and along the face-to-tip distance are more uniform. The stability of the model and loading condition of the support are also better. (3) The face-to-tip distance and cutting height are negatively correlated with the stability of the face-end roof. When the face-to-tip distance is 0.5 m, the top coal displacement is less than 45 mm, and the shield loading situation and model stability are better. When the cutting height is 3 m, the displacement of the top coal is small, which benefits the stability of the face-end roof. (4) The rotating failure of the overlying roof deteriorates the coupling relationship between the supports and surrounding rocks, reduces the available effective support resistance, and finally leads to the loss of stability of the face-end roof and the development of roof collapse in the face-to-tip area. Therefore, in the mining process of the long-wall top coal caving face, it is necessary to adjust the position of the shields and the coal cutting height in a reasonable manner, to reduce the face-to-tip distance by rapidly advancing the supports, so that the face-to-tip distance is minimized as small as possible.

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