Near Field Radiant Energy Assessment Of Rock Failure And Engineering Application Based On Brune Model

Radiant energy is an extremely important source parameter in the assessment of geological disasters such as mines and hydropower stations.It is an important index for Disaster grade discrimination.the geometric diffusion,inelastic attenuation during the propagation process and energy compensation should be considerd for the calculation of the Microseismic radiant energy,and we need select the suitable source spectrum model.However,the Andrews method that is used to calculate the radiation energy of earthquakes and microearthquakes does not take the inelastic attenuation and energy compensation into considerition.And the corner frequency and the low-frequency amplitude are the key factors of radiation energy calculation.These two source parameters are fitted by the source spectrum,however,it is necessary to further study whether the engineering microseismic source spectrum model accords with the seismic source spectrum model?that is the Brune model?.In view of this,based on the theoretical knowledge of seismology and according to the monitoring data of Engineering microseismic,a method for calculating the source spectrum suitable for microseismic monitoring is proposed,mainly considering the geometric diffusion and the inelastic attenuation coefficient;Secondly,target function of the source spectrum parameters fitting is improved and the near field source spectral model of the engineering microseismic are determined.The correct corner frequency and low frequency amplitude are obtained by fitting the source spectrum.Finally,the calculation method of near-field radiation energy for engineering microseismic is presented,considering the energy compensation,and the method is applied to the evaluation of the actual engineering microseismic radiation energy.Through the above work,this paper mainly obtains the following research results:?1?The seismic source spectrum of the engineering microseismic monitoring proposed in this paper,neglecting the site effect,mainly considering the geometric diffusion and the inelastic attenuation effect,and the instrument response needs to measure the transfer function of the instrument in advance.After eliminating the above factors,a more reasonable source spectrum can be obtained.?2?When the source spectrum of each wave source is optimized,the correlation coefficient threshold R₀ is set to 0.8 more reasonably.After removing the displacement spectrum of the bad sensor,the source spectrum curves are more concentrated.?3?The inelastic attenuation coefficient of two projects is analyzed by multi sensor multiple seismic source joint inversion.The Q₀ of baihe tan hydropower station is larger,the medium is more uniform and the attenuation is slower,the Q₀ of the Ashele copper mine is smaller,the medium is less uniform and the attenuation degree is higher.?4?After improving the fitting target function of the displacement spectrum,the fitting effect is optimized to a certain extent.Based on the analysis of rock failure events in two projects of the Ashele mine and the baihe tan hydropower station,the calculated value of energy E used by the traditional target function fitting is about 1times larger than lg target function.After improving the target function,the overestimation of energy is reduced,also the misclassification of disaster grade is reduced.?5?The source spectra of the rock rupture events of the Ashele copper mine and the Baihe tan hydropower station are all suitable for the?^-3 model.Compared with the?^-2 model,the corner frequency f₀ obtained from the fitting of the?^-3 model is larger,while the low frequency amplitude?₀ is smaller and the energy value is larger.?6?A method for calculating near field radiation energy of rock failure events is proposed.The radiation energy E obtained from the calculation of attenuation coefficient without considering the attenuation coefficient will be much smaller than that considering attenuation coefficient,and the radiation energy E without considering the energy compensation,and degree of reduction increases with the increase of the corner frequency.In this paper,the method of calculating the near field radiation energy of Engineering microseismic based on the Andrews method has a good evaluation on the calculation of the engineering microseismic energy,and provides a reasonable quantitative index for the determination of the grade of the engineering disaster,such as rock burst.