Abstract
During the excavation of deep coal and rock mass, the radial stress of the free face changes from three-dimensional compression state to two-dimensional stress, bearing the combined action of dynamic disturbance and static load at the same time. With that, many mines suffer from dynamic disasters, such as coal and gas outburst, rock burst and rock caving during deep mining excavation, which is often accompanied by plate crack, spalling and other disasters, seriously affecting the stability of stope and roadway. Taking thin rectangular coal and rock mass as the research object, the dual equation of the free vibration was derived and the exact solution model of the free vibration was established with the use of Hamilton dual system. Based on the action characteristics of the uniform impact load, the effective mode of the forced vibration was obtained by using the Duhamel integral principle and the orthogonality of the mode function. Based on the third strength theory and the numerical simulation results, the dynamic damage process and development trend of coal and rock mass were analyzed under uniform impact load. It was concluded that the starting position of dynamic damage can be judged by the first order main mode, and the development direction and trend of the damage can be judged by the fifth and sixth order main modes. It was concluded that the vibration mode functions of coal and rock mass with four side fixed (C-C-C-C), the two sides fixed and simply supported on the other (S-C-S-C) are mainly composed of three modes that are the first order (dominant frequency), the fifth order and the sixth order, from which the dynamic damage mechanism is preliminarily studied.
Highlights
With the increasing demand for mineral resources and the continuous consumption of shallow resources, the mining of domestic and foreign coal mines and metal mines has gradually shifted to the deep [1] [2]
During the excavation of deep coal and rock mass, the radical stress of the free face changes from three-dimensional compression state to two-dimensional stress, so many mines have suffered from dynamic disasters, such as coal and gas outburst, rock burst, rock caving and other dynamic disasters in deep mining, which is often accompanied by plate crack, spalling and other disasters, seriously affecting the stability of stope and roadway [3] [4]
Based on the characteristics of uniform impact load, the effective vibration mode solution of thin coal and rock mass under forced vibration was studied by using Duhamel integral principle, and the dynamic damage failure process and mechanism of thin coal and rock mass were analyzed, which are beneficial to revealing the mechanism of coal rock dynamic disaster
Summary
With the increasing demand for mineral resources and the continuous consumption of shallow resources, the mining of domestic and foreign coal mines and metal mines has gradually shifted to the deep [1] [2]. Based on the thin plate model, many scholars have carried out extensive researches on the mechanism and mechanical behavior of coal and rock mass plate cracking failure and plate cracking (spalling) buckling rock burst. Due to the vibration of the thin plate under the action of external force has a significant impact on its mechanical properties, so that researches on the failure mechanism and development trend of coal and rock mass under dynamic load disturbance are still in the qualitative analysis stage, which could not provide strong support for fundamentally revealing the occurrence mechanism of coal and rock dynamic disaster. Based on the characteristics of uniform impact load, the effective vibration mode solution of thin coal and rock mass under forced vibration was studied by using Duhamel integral principle, and the dynamic damage failure process and mechanism of thin coal and rock mass were analyzed, which are beneficial to revealing the mechanism of coal rock dynamic disaster
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