Study on Mechanism and Countermeasures of Broken Floor Heave in Mining Roadway

Aiming at the severe floor heave of the transportation roadway of 10502 working face in Yitang Coal Mine, the mechanics model of floor heave was established and the mechanism and control methods were studied through site measurement, rock mechanics experiment and theoretical analysis. The results show that the plastic slip line field is formed in the surrounding rock of the broken floor under the bearing pressure transferred by the two sides of the coal body, when the width of passive Rankine area formed by floor rock mass under effective abutment pressure zone is equal to the width of roadway, the width is defined as the floor heave affected area. By applying the bottom angle bolt, it can not only cut off the plastic slip line of the floor, prevent the surrounding rock from moving, but also act as a “pin” to reinforce the “weak surface” of the floor and improve its shear strength, so as to control the surrounding rock of the floor. When the support strength of the anchor at the bottom angle reaches 0.5 MPa, the monitoring results show that the maximum floor heave of the roadway with the advance of the working face is only 86 mm.