Multi-parameter Precision Observation Experiment And Application Research On Coal Rock Mass Failure Process

With the increase of mining depth and strength,coal rock dynamic disasters such as rockburst,coal and gas outburst have become important problems that plague coal mines' safe and efficient production.The mechanism of coal mine impact ground pressure is not clear.Traditional monitoring and early warning measures have the disadvantages of long test time,high labor intensity,and measurement results are easily affected by human factors.Therefore,the establishment of a new monitoring and early warning system is the development direction of intelligent mine construction.In the process of coal rock dynamic disaster accidents such as rockburst,crack incubation,generation,expansion,and destruction are important factors that change the strength of coal rock and induce coal rock dynamic disaster.In view of this,a multi-parameter accurate experiment system including acoustic and electrical signals and crack propagation images is established in this paper.Compression failure experiments are performed on standard coal and rock samples using three stress paths:uniaxial compression,cyclic loading,and hierarchical loading.And the data acquisition system records crack propagation images and acoustic and electrical signals during loading.The force,displacement,strain,resistivity,electromagnetic radiation,acoustic emission and other indicators were compared and analyzed on the same time number axis.The quantitative and automatic processing of the captured images obtained the length and expansion rate of the cracks,which made the parameters of the fracture process The accuracy reaches the millisecond level in time,and new warning indicators such as resistivity change rate and crack equivalent length are proposed,and the early warning time difference of acoustic and electrical signals leading to stress damage is obtained.Based on the statistical analysis of multi-parameter signals during loading,a constitutive model of fractured coal and rock is proposed.This model is used to Flac 3D,stress concentration areas in working faces provide guidance for monitoring and early warning of key areas.The theory of borehole-roadway double relief circle is put forward,and the inverted "?"-type kilometer drilling arrangement is proposed accordingly.Finally,a multi-parameter early warning system for dynamic phenomena of coal and rock based on electromagnetic radiation,acoustic emission and images was proposed.It was applied on-site at two coal mining faces in Wudong and Shadunzi coal mines with risk of rockburst and coal parameters were measured before and after measures were taken in the dangerous area.It is proved that the system is feasible and has theoretical and engineering significance for early warning of dynamic disasters in coal mines.