Prediction And Control Research On Structural Destabilization Of Complex Coal-rock Masses

Structural type of coal-rock masses would form a new more complex structure withdynamic loading under mining activity. Large-scale fault-like structure is formed whenhorizontal section top-coal caving is applied in the steeply coal seams. Severely deformationof the structure is happened with high loading. Particularly the stress is abnormal in horizontaldirection. Destabilization of dynamic structure, large-scale rock-mass caving are easilydevelopmented in the site.Key factors for controlling dynamic hazards are connected with material, structural andoccurrence traits of typical complex coal-rock masses. Caving of roof and floor are fallen intotriple categories: collapse roof, tumble roof and slump floor. Arch of spanning structurecomposed with roof-broken coal-floor tends to a temporary stable strcuture. Semicurrculararch structure has been evolved into the approximately parabolic structure with higher heightof arch and larger spanning length. Top coal is hardly excavated with such a arch structure,while coal-rock masses are also possible to destablize in large-scale area resulting in methaneemission, support pressure increment. broken process of roof is evolved "bend-break-slip".And floor would uplift and slide. The structure of arch is extremely unstable. With height andlength of arch increasing, the collapse roof would be caving under nonsysmetric pressure andit would slide quickly in bedding plane with its self-weight, which influenced the stability ofsupportings and safe excavation in the site. Without enough bashing materials, a large-scaleand high slope-angle mined-out area has been formed which resulted in being lack of supportforce at floors. The weight of basic floor made tumble roof unstable. With much moreloadings than ever, the fault-like structure has been activated for harder dynamic laodings inthe stope.The traits of destabization of complex coal-rock masses is that with coal excavation,internal strcuture of the workingface is evolved continuously resulted in broken down of unstable arch of spanning structure and chain reaction of large fault-like structure. Thedynamic destablization of supreme-scale mined-out area would be catastrophic.Combined with precursor information of rock-mass destabilization and energyaccumulation, prediction methology of rock-mass destabization has been gotten withsonic-light-electric measurements including stress-strain, acoustic emission, in-situ realdeforamtion monitoring. Judgment parameters building up a comprehensive evaluationfunction would be assessed together for rock-mass destabization in complex mining condition.Fast dynamic prediction and control technique is establize with analyzing rock-massgeological condition and the relative mechanic behavior. A new methology for predictingrock-mass destabilzation is built up with multi-source information coupled analysis, hybridblasting and hydraulic fracturing for weakening roof and coal, optimization of roadwaysupporting. The practical theories and technologies concluded with all above listed wouldoffer a security for improving the whole colliery safety, which possesses a lot of importantscientific and industrial value for colliery safety.