Study on the Floor Heave Mechanism and Control Technology of a Gob-side Roadway Under Advanced Mining Influence

Aiming at the difficult problem of floor heave affected by advanced mining in gob-side roadway in deep mining, taking the return air flow trough of 3109 working face of Ma Tai Hao Coal Mine as the engineering background, adopting the systematic research method of "field monitoring-numerical simulation-theoretical modeling-engineering verification", analyzing the appearance characteristics of floor heave affected by advanced mining, carrying out the design of anti-arch bearing structure of floor of gob-side roadway and its mechanical stability analysis, studying the technical scheme of surrounding rock control of floor heave affected by advanced mining in narrow coal pillar gob-side roadway and carrying out engineering verification, providing theoretical basis and practical reference for the influence of advanced mining in gob-side roadway floor heave. The results are as follows: (1) The influence rules of vertical stress, lateral stress, span and elastic modulus on floor heave are revealed: the depth, span, vertical stress and lateral stress of inverted arch horizontal beam are positively correlated, and negatively correlated with elastic model and thickness; (2) Dual stability criteria are constructed: bending tensile failure criterion controls the upper boundary normal stress of the middle part of the reverse arch ≤ the tensile strength of the floor medium, and shear failure criterion controls the neutral surface shear stress of both ends ≤ the shear strength of the floor medium, so that the reverse arch structure of the floor can not be destroyed and unstable under the advanced mining dynamic stress; (3) The technical scheme of "comprehensive bolting and grouting reinforcement + reverse bottom arch" is put forward, and the feedback effect of field application is remarkable, the amount of bottom heave is reduced by 55.7%, and the amount of slope bottom angle moving close is reduced by 55.4%, which meets the requirements of the code and provides reference for the control of bottom heave in deep roadway with high stress and narrow coal pillar.