Numerical simulation of the influence of bedding on characteristics of magnetic signals emitted from coal failure

In order to improve the mechanism of the technique used to monitor the coal mine disasters by magnetic sig- nals,a magnetic-mechanical coupling model was built based on elastic mechanics,damage mechanics and statistics. Combining with the RFPA2D,the influence of bedding on failure pattern and magnetic signal char-acteristics was stud- ied. The results show that:① Coal samples without bedding exhibit the characteristics of single slope shear failure, while samples with vertical beddings experience a process of slip-shear-tensile failure along the beddings. Samples with horizontal beddings suffer local tensile failure firstly,and then cracks propagation in a shape of divergence. ② Magnet- ic pulses and energy accumulated in the whole process of sample failure can be divided into four stages,which are zero stage,slow increase,rapid increase and smooth change,respectively. ③ Accumulated magnetic pulses and energy of samples with vertical beddings is much lower than that of samples with horizontal beddings,and the difference value of magnetic energy is much higher than that of magnetic pulses. ④ The quantity of bedding of the sample with horizontal beddings has a good positive linear correlation with magnetic pulses and magnetic pulses respectively,and the increase amplitude of magnetic energy is higher than that of magnetic pulses;for the samples with vertical beddings,the quantity of bedding also has a negative linear correlation with magnetic energy,while no correlation characteristics between bed- dings and magnetic pulses can be seen.