Effect evaluation of curtain grouting in burnt rock aquifer using electrical CT and seismic CT
Burnt rock water damage seriously affects the safe production of coal mines,and adopting curtain grouting to control burnt rock water damage is a better way at present.Taking the curtain grouting project of water damage in burnt rock of Ningtiaota Coal Mine as an example,the effect of curtain grouting in burnt rock aquifer was comprehensively evaluated by means of drilling core validation,high-definition video,electrical CT and seismic CT methods.The results showed that four of the five core inspection holes were filled with cement slurry in the weathered bedrock section,while the J5 hole was filled with slurry at 120.8-121.2 m of burnt rock,and there was no water leakage or drilling loss during the construction of the inspection holes.The high-definition video results showed that the wall of the inspection hole was smooth,with no obvious fissures,and the original stratum fissures were clearly visible in the local area,which were filled and compacted by the slurry,with no residual fissures.The cross-hole resistivity CT results showed that the resistivity of the formation increased significantly after grouting,and the resistivity value of the strongly weathered sandstone increased most signifi-cantly.The depth range of the strongly weathered layer was more than two to four times higher than that of the strongly weathered layer,and the resistivity of the stratum in all profiles was obviously and effectively increased.The inter-hole seismic CT results showed that the velocity ranged corresponding to the medium and strong weathering layer before grouting was mainly distributed in the range of 1 600-2 800 m/s,and the lateral velocity varied greatly.After grouting,the velocity range was concentrated in 1 800-3 800 m/s,of which the range of velocity in 1 600-2 000 m/s was obviously reduced,and the speed in most areas were above 2 200 m/s.All the above four in-dexes reflected the overall good effect of this grouting project.The research results can provide a reference for the evaluation of the effect of the water damage control project in burnt rock under similar conditions.
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