In order to improve the prediction of rock burst with charge induction

the charge monitoring test was carried out on fractured coal samples under uniaxial compression by the self-developed charge monitoring system in the laboratory. The failure types

mechanical properties of coal samples and the law of the charge time-frequency domain signals under different damage types were analyzed emphatically. Moreover

the test

results were verified in practice. The results show that the deformation and failure characteristics of coal samples can be divided into single shearing type

conjugated shearing type

and shattered type. The charge time-domain signals of coal samples with single shearing occur only in the early stage of post peak failure

and the stress falls to about 97%σ

c

. Since the signal characterizes a single burst with higher amplitude

discrete charge frequency distribution and the main frequency of 250 Hz

it is difficult to capture the precursory information. Those characteristics of charge signal indicate that the corresponding engineering coal body may occur a localized failure with releasing the accumulated energy instantly

which leads to significant impact hazard. The charge time-domain signals of coal samples with conjugated shearing are produced in the later period of intensified damage

and the stress reaches（85%～100%）σ

c

. The signal has an interval burst

and the main frequency is 150 Hz.This indicates that the partitioned rupture occurs with accumulated energy released gradually

and the impact hazard degree is the second. The charge time-domain signals of shattered coal samples are generated in the early stage of intensified damage

and the stress reaches（70%～85%）σ

c

. The premonitory information is easy to capture because the signals burst continuously with low amplitude and the main frequency of 0 Hz. These results indicate that the coal body may be homogeneously broken with accumulated energy released slowly

and the impact hazard degree is lower. The field monitoring results show that characteristics of charge signals both in crushing area of working face and the occurrence of coal firing gun are highly similar to those charge signals which are produced by coal samples in homogeneous shattered type and single shearing type in the laboratory. These results verify the reliability of the results obtained from the laboratory.