Evaluation method for rockburst-preventing effects by drilling based on energy-dissipating rate

Evaluation method for rockburst-preventing effect by drilling from the perspective of energy was studied based on theoretical analysis, laboratory tests and numerical simulation.The total amount calculations of stress before and after drilling show that drilling in coal results in “pressure regulation”, not only “pressure relief”.With respect to the perspective of stress, the evaluation from the perspective of energy is easier.Uniaxial loading and unloading tests of coal specimens from different coal mines show that the calculation results using the energy calculation formula for linear elastic materials are greater than the actual value, and the stronger the bursting liability of coal, the smaller the calculation error.Modified formula based on elastic energy index is proposed.The variation characteristics of elastic strain energy in surrounding rock are dominated by the characteristics of doing work by the maximum principal stress.It is related to rock orientation and lateral pressure coefficient whether the elastic strain energy can be accumulated when the stress regulates in surrounding rock.On this basis, the concept of energy dissipation rate for drilling is proposed, which can be used to evaluate different drilling designs, which is realized by numerical simulation through FLAC^3D.There is a typical power function relationship between borehole diameter and rockburst-preventing effects, which is negatively correlated with seam strength.Compared with φ100 mm borehole, the energy dissipation effort of φ150 mm one is 2.9 times more, and φ200 mm one is 6.5 times more.