Floor heave mechanism for gob-side entry retaining with concrete blocks and control method: A case study

Abstract

The issue of significant floor heave deformation in gob-side entry retaining has long been a challenging problem in the context of longwall mining. This paper studies the floor heave failure mechanism and control method for gob-side entry retaining with concrete blocks in Guizhou Faer Coal Mine in China. Based on Rankine’s earth pressure theory, the effective shear stress equation for the plastic slip of roadway floor is established. The deformation mechanism of floor heave in a retaining roadway with a block wall is revealed in this study. The new comprehensive control method is proposed, encompassing roof pre-splitting blasting for pressure relief, reinforcing cables for roof control, double directions control bolts for concrete block, and pliability cushion yielding pressure. FLAC^3D numerical calculation model is established, which shows that the new method can effectively reduce the average vertical stress peak value of the entity coal floor by 34.6% and significantly reduce the pressure source causing the roadway floor heave. Besides, a multi-parameter real-time online monitoring system for mine pressure was designed, and field tests were carried out. The results show that the maximum value of roadway floor heave under the new method is 163 mm, reduced by 66.9%, and the roadway floor heave is effectively controlled. These research findings offer a fresh perspective and new ideas for controlling floor heave in mining operations.

Keywords

Gob-side entry retaining / Floor heave mechanism / Plastic slip / Control methods / Mine pressure monitoring

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

Fundings for this work were provided by the National Natural Science Foundation of China (Grant No. 52074300), China University of Mining and Technology (Beijing) fundamental scientific research funds—Doctoral students Top-notch Innovative Talents fostering funds (Grant No. BBJ2023047), Yueqi Young Scholars Project of China University of Mining and Technology Beijing (Grant No. 2602021RC84), and Guizhou Province Science and Technology Planning Project (Grant Nos. [2020]3007, and [2020]3008).

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