Energy release characteristics and mechanism of rock beam fracture: a case study from laboratory tests to field application

In the process of underground coal mining, the energy released by fracture of roof beam is the main source of rock burst energy. This part of energy is affected by its size and material properties. This study redefined the geometric parameter (GEO) and material parameter (MAT) that characterize the properties of rock beams. Three point bending tests were designed and carried out on account of the two parameters. The parameter representing the energy release capacity of rock beams was proposed, and the effects of GEO and MAT on the parameter were quantitatively analyzed by numerical simulation. Finally, a new method for predicting the energy released by rock beam fracture was proposed. The results show that with the increase of MAT and GEO, the total energy stored in the rock beam and the energy released during fracture both showed an upward trend. MAT is the main parameter that affects the load–deflection curve and AE parameter distribution characteristics, while the influence of GEO on the test curve was only reflected in the numerical change. The energy release ratio ranges from 0.5 to 0.7, which exhibits a quadratic function relationship with the MAT of the rock beam. The proposed new method for predicting the energy released by rock beam fracture was successfully used in the 10,301 working face of Jining No. 2 Coal Mine. The prediction results of the basic roof and the direct roof beam were consistent with the field microseismic test results, and the errors were only 10.88% and 11.50%, respectively.