关键词: 孤岛工作面, 真三轴卸荷试验, 沿空掘巷, 围岩协同控制

Abstract: Aiming at the control problem that the surrounding rock of small coal pillar gob-side entry driving in island working face is prone to large deformation，taking the air roadway of the second level south wing coal pillar working face of Hengyuan Coal Mine as the engineering background，the mechanical re⁃ sponse，crack evolution characteristics and surrounding rock control mechanism of coal body under the con⁃ ditions of excavation unloading and post-unloading support were studied by means of true triaxial unloading�support path test，acoustic emission monitoring and field mine pressure monitoring. The results show that the coal under the two stress paths of single-side unloading and post-unloading support is characterized by progressive failure. Compared with the single-sided unloading path，the peak strength of the sample under the support path increases from 58.13 MPa to 89.07 MPa，with an increase of 53.23%，and the peak axial displacement increases from 4.53 mm to 6.39 mm，with an increase of 41.06%，indicating that the support compensation significantly improves the bearing capacity and deformation coordination ability of the coal body. The coal failure under the two paths is dominated by tensile cracks，but the internal crack evolution under the support path is more persistent，and the proportion of intermediate frequency acoustic emission events increases from 68.70% to 88.43%. Field monitoring shows that，under the original support condi⁃ tions，the surrounding rock deformation in the test section exhibits obvious zonal characteristics. The sur⁃ rounding rock tends to be stable beyond 65 m from the second horizontal south wing coal pillar working face. The area between 30 m and 65 m from the second horizontal south wing coal pillar working face is a progres⁃ sive deformation zone. The area within 30 m from the second horizontal south wing coal pillar working face enters the stage of severe deformation. The peak value of roof separation is 37.2 mm，and the maximum con⁃ vergence of roof and floor and two sides is 421 mm and 463 mm respectively. Based on the test results and the law of mine pressure in the field，the coordinated control technology of“anchor beam + high-strength anchor full-length anchoring + intermittent repeated grouting modification”is proposed. After the engineer⁃ ing application，the stable area of surrounding rock is shortened to 40 m away from the south wing coal pillar working face of the second level，and the maximum relative displacement between the roof and floor and the two sides is reduced to 299 mm and 327 mm respectively，which is about 29 % lower than that before optimi⁃ zation，and the roof separation is controlled within 33 mm. The research results can provide reference for the large deformation control of surrounding rock of small coal pillar gob-side entry driving in island working face under similar conditions.

Key words: island working face, true triaxial unloading test, gob-side entry driving, surrounding rock coordinated control