基于电法CT和地震CT的烧变岩含水层帷幕注浆效果评价

Effect evaluation of curtain grouting in burnt rock aquifer using electrical CT and seismic CT

烧变岩水害严重影响煤矿安全生产,采取帷幕注浆治理烧变岩水害是目前效果较好的方式。以柠条塔煤矿烧变岩水害帷幕注浆工程为例,采用钻探取心验证、高清视频、电法CT和地震CT手段,综合评价了烧变岩含水层的帷幕注浆效果。结果表明,5个取心检查孔中的4个在风化基岩段均见到水泥浆液充填薄层,J5孔在120.8~121.2 m烧变岩处见浆液充填,且检查孔施工过程中均未出现漏水、掉钻现象。高清视频结果显示,检查孔孔壁光滑,无明显裂隙,局部明显可见原地层裂隙被浆液充填密实,无残余裂隙。跨孔电阻率CT结果显示,注浆后地层电阻率明显升高,其中强风化砂岩的电阻率值升高最为明显;强风化层所对应的深度范围地层电阻率均提升2~4倍,所有剖面地层电阻率均明显有效提升。孔间地震CT结果显示,注浆前中、强风化层所对应的速度范围主要分布在1600~2800 m/s,且横向速度变化较大;注浆后速度范围集中在1800~3800 m/s,其中速度在1600~2000 m/s的范围明显缩小,且大部分区域速度均在2200 m/s以上。以上4种指标均反映了本次注浆工程的效果整体较好。研究成果可为类似条件下烧变岩水害治理工程的效果评价提供参考。

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 significantly.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 1600-2800 m/s,and the lateral velocity varied greatly.After grouting,the velocity range was concentrated in 1800-3800 m/s,of which the range of velocity in 1600-2000 m/s was obviously reduced,and the speed in most areas were above 2200 m/s.All the above four indexes 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.