Study on the development characteristics of the water-conducting fissure zone in large-height and ultra-wide working faces at Sihe Coal Mine

Wang Guoliang; Wang Fei; Wang Shuyong; Cheng Fengfei; Du Feng

doi:10.16186/j.cnki.1673-9787.2023110011

Abstract：Objectives To investigate the development characteristics of the water-conducting fissure zone in large-height and ultra-wide working faces at Sihe Coal Mine,using the 6306 working face as the study sub-ject.Methods The variation in apparent resistivity of the roof rock strata before and after mining was mea-sured using the parallel electrical method.Numerical simulations were also conducted to analyze the devel-opment characteristics of the water-conducting fissure zone.Results(1)The apparent resistivity of the roof strata changed significantly due to mining.The original strata exhibited an apparent resistivity of 150～300 Ω·m,while severely damaged strata reached up to 680 Ω·m.Field measurements showed that the cav-ing zone height was 21.0 m,with a caving ratio of 3.5.The lower limit of the water-conducting fissure zone was measured at 82.5 m,with a fissure ratio of 13.8.The upper limit was not captured during the observa-tion period.(2)Numerical simulations indicated a caving zone height of 21.9 m.When the working face ad-vanced to 300 m,the water-conducting fissure zone reached its maximum height of 90.6 m.The final mor-phology of the fissure zone exhibited a saddle-shaped distribution.(3)Since the caving zone develops rap-idly,it had already fully formed during the monitoring period,resulting in good agreement between field measurements and numerical simulations.However,the water-conducting fissure zone requires at least 1～2 months to fully develop.Due to the short effective monitoring time,significant deviations existed between field measurements and simulation results.Conclusions The water-conducting fissure zone in the large-height and ultra-wide working faces at Sihe Coal Mine develops to a height of 82.5～90.6 m,with a final saddle-shaped morphology.The results provide important guidance for the prevention of roof water hazards and for the scientific extraction of gas from goafs.