Study on Surrounding Rock Control Technology of Gob-Gob Roadway Driven by Fully Mechanized Caving With Large Mining Height and Small Coal Pillar in Extra Thick Coal Seam

To investigate the ground pressure control in gob-side roadways with small coal pillars in deep and high fully mechanized caving faces, a study was conducted based on the return airway of the 2-2 coal seam in the 130203 face of Zao Quan Coal Mine of Guo Neng Ning Mei Group. The deformation of the original roadway and the failure of bolts and cables were analyzed. Based on the soil pressure theory, a stress field model was constructed for the rock surrounding the roadway. Calculations showed that the internal stress field ranged 8.8–9.5 m, the advance peak pressure ranged 15–22 m, and the bearing pressure influence ranged 175–190 m. Through FLAC^3D simulations, it was found that the stress on a 5-m coal column was 7.01 MPa, while the stress on a 15-m coal column reached 65.25 MPa. Field measurements showed that the deformation of small coal pillars was 690 mm, compared to 370 mm for solid coal pillars, with asymmetric deformation. The bottom heave varied to 750 mm, with a local maximum of 1400 mm. The analysis showed that the roof rock beam fractured above the side of the 5 m small coal pillar due to the influence of an anticline structure, leading to the proposal of an asymmetric control mechanism. Grouting pillars and individual supports were used for support, and the technology was successfully applied in the field, meeting the production requirements. The gob-side roadway technology with small coal pillars was successfully implemented in the 130203 face, providing a scientific basis for mining in similar mines.