Mechanism and prevention of floor heave in deep seam bottom coal mining roadways

TIAN Xiaobing; DENG Hui; XIE Fuxing; SHI Xingxing; DONG Zhe; ZHANG Huaizhong; ZHENG Zheng

doi:10.11799/ce202501009

Abstract：In order to explore the mechanism of floor heave in the roadway of the mining face with reserved bottom coal and the corresponding surrounding rock control technology,a systematic study was conducted on the 402104 track level roadway of Hujiahe Coal Mine using mine pressure monitoring,theoretical calculation analysis,numerical simulation,and on-site industrial test.The results showed that as the thickness of the reserved bottom coal in the roadway increased,the maximum value and range of vertical upward bending deformation of the beam structure in the floor have both increased to a certain extent.At the same time,it is more prone to deformation and fracture under higher bending moment forces,resulting in longer block structures and more severe floor heave caused by subsequent rotational transport;The increase in the thickness of the reserved bottom coal leads to a trend of horizontal and vertical displacement of the arch foot position away from the roadway,while the increase in the cohesion of the reserved bottom coal causes the horizontal displacement of the arch foot position to be closer to the roadway,and the vertical displacement to be farther away from the roadway;As the position of the arch foot gradually moves away from the roadway,the range of plastic deformation and damage to the coal and rock layers inside the floor increases,leading to an increase in the deformation of both sides of the roadway and the floor;By applying bottom angle diagonal anchor cables and anchor rods,the horizontal movement of bottom coal and its shear resistance can be controlled.At the same time,applying floor anchor rods or short anchor cables can control the vertical movement of bottom coal and its strength value.During the on-site industrial test,a surrounding rock control scheme was proposed.The overall control effect of the surrounding rock was good,and the maximum bottom heave during the entire tunnel service period did not exceed 0.5 m.