Study on localization method of coal rock deformation for rock burst prediction

Rockburst prediction is the premise and foundation of rockburst prevention and control，and is an impor⁃ tant topic in rockburst research. Aiming at the problem that the intrinsic relationship between the precursor and the gestation process of rockburst is unclear，a prediction method of rockburst with the localization of coal and rock deformation as the precursor is put forward. Based on the energy principle of classical mechanics，the method starts from the inherent characteristics of coal and rock deformation and failure and the essence of rockburst instability.According to the principle of virtual displacement and stability theory，the critical conditions of rockburst and the con⁃ ditions of coal and rock deformation failure localization are deduced and obtained，and the internal relationship be⁃ tween coal and rock deformation failure localization and rockburst is analyzed. Based on the gradient plasticity theory，the deformation failure localization model of coal and rock is established by introducing the internal length pa⁃ rameter，and the influence factors of deformation failure localization band are analyzed. Also，the experimental method of measuring the internal length parameter is given，and the phenomenon that the deformation and failure concentrate in a certain area and the concentrated area has a certain scale is theoretically analyzed. According to the temporal and spatial evolution characteristics of deformation failure localization，the spatial aggregation，gradient saliency and curva⁃ ture saliency indexes are introduced，and the deformation failure localization state is identified from the attributes of “time evolution” and “structure evolution”. The preliminary application of deformation failure localization predic⁃ tion method is studied，and the experimental acoustic emission data and field microseismic data are respectively used to predict the damaged area of coal and rock specimen and the dangerous area of coal mine rockburst. The study shows that the starting condition of coal and rock deformation failure localization is the same as the critical condition of rockburst，that is，the gestation and evolution process of rockburst is consistent with that of coal and rock deformation failure localization. The width of deformation failure localization zone is related to the internal length parameters of the material and the impact energy index of the coal. With the increase of the internal length of the material，the width of deformation localization zone increases linearly， and with the increase of the impact energy index of the coal，the width of deformation failure localization zone decreases nonlinearly. According to the experimental and field preliminary application results，it shows that the spatial aggregation，gradient saliency and curvature saliency inde⁃ xes can describe and track the temporal and spatial evolution characteristics of deformation failure localization， and the method of deformation failure localization to predict the dangerous area of rockburst is feasible.