Dynamic fracturing effects of the immediately overlying thick,hard roof in deep mining and the stability mechanisms of gob-side roadways

Zhang Guangchao; Liu Yuhang; Yin Maosheng; Zhang Zhaoyun; Zheng Canguang; Zhang Ronggang; Lei Teng; Zhao Xipo

doi:10.16186/j.cnki.1673-9787.2025080022

Abstract：Objectives To address impact-induced instability of gob-side roadways beneath immediately over-lying thick,hard roof in deep mining faces of the Yanzhou mining area,the transport roadway of the 18306 working face in Jisan Coal Mine is taken as the engineering background to investigate the underlying disaster mechanisms and propose effective control technologies.Methods A comprehensive approach inte-grating field investigation,theoretical analysis,numerical simulation,and in-situ testing is employed.A cantilever-beam mechanical model of the immediately overlying thick,hard roof is established to systemati-cally analyze its mining-induced load-bearing behavior and the evolution characteristics of energy accumula-tion.The influences of roof properties on the catastrophic instability of gob-side roadways are revealed,and the definition and evolutionary process of dynamic instability under thick,hard roof conditions are clarified.On this basis,a layered collaborative control system integrating variable-diameter borehole sealing and coupled roof anchoring–grouting reinforcement is proposed and implemented.Results 1.The accumulation and distribution of mining-induced energy in thick,hard roof strata are significantly influenced by their in-herent geological and mechanical properties.Higher roof strength and greater thickness correspond to lower peak bending energy and weaker energy concentration,whereas longer roof suspension lengths and greater overlying loads result in higher peak bending energy accumulation and a more extensive high-stress zone.2.Dynamic instability of deep roadways essentially results from rapid energy release and structural degrada-tion of surrounding rock under strong dynamic disturbances induced by thick,hard roof fracturing,typi-cally manifested as coal ejection and support system failure.3.A layered collaborative control strategy com-bining pressure relief through variable-diameter borehole sealing and roof anchoring–grouting reinforce-ment is developed,forming a targeted protection system for immediately overlying thick,hard roofs.Con-clusions Field tests demonstrate that the proposed technology effectively ensures the stability of surround-ing rock in gob-side roadways beneath immediately overlying thick,hard roofs,providing a valuable refer-ence for support design in similar roadway conditions.