复杂散体状顶板回采巷道围岩注浆改性控制分析

Analysis on Gateway Improvement Control by Surrounding Rock Grouting in Complex Granular Roof

复杂散体状顶板巷道围岩破坏严重,变形量大,支护困难。通过对复杂散体状顶板巷道围岩变形破坏特征与失稳原因分析,研究了不同配比似膏体注浆材料的浆液密度、析水率、流动度特征,探明了不同水灰比、粉煤灰掺量对似膏体注浆材料强度的影响机制,确定了似膏体注浆材料优化配比与注浆加固支护方案。结果表明:复杂散体状顶板巷道围岩表现为顶板破坏严重呈网兜状下沉,高低帮呈整体“凹”型膨胀变形;散块体、弱胶结、高应力、软煤体、支护失效是巷道围岩失稳的主要原因;随着水灰比、粉煤灰掺量增大,浆液析水率与流动度呈增加趋势、浆液密度则呈降低趋势,水灰比对浆液流动度影响大于粉煤灰掺量;浆液结石体破坏强度随着水灰比与粉煤灰掺量的提高分别表现为加速衰减姿态与急剧下降—缓慢增加—缓慢下降趋势;似膏体注浆材料优化配比的水灰比与粉煤灰掺量分别为0.6∶1与80%;采用锚杆(索)+似膏体注浆控制技术方案30 d后,顶板最大下沉量小于80 mm,两帮最大收敛量小于70 mm,巷道围岩稳定性较好。

The gateway with complex granular roof surrounding rock fails seriously with large deformation and difficult support.The paper analyzed the deformation damage characteristics and failure causes of surrounding rock with complex granu-lar roof,studied the characteristics of slurry density,water extraction rate and fluidity of similar-paste grouting materials with different proportions,explored the influence mechanism of different ash-sand ratio and coal ash content on the strength of simi-lar-paste grouting materials,and determined the optimal ratio of similar-paste grouting materials and reasonable grouting rein-forcement support scheme.The results showed that gateway roof of complex granular surrounding rock was damaged seriously with mesh pocket sinking,overall intrusion and"concave"expansion deformation at high and low sides respectively.The main causes for the instability of gateway surrounding rock were granular block,weak cementation,high stress,soft coal and support failure.With the increase of ash-sand ratio and coal ash content,the water extraction rate and fluidity of slurry increased,while the slurry density decreased,and the influence of ash-sand ratio on slurry fluidity was greater than coal ash content.With the increase of ash-sand ratio and coal ash content,the failure strength of slurry grouts showed accelerated attenuation and sharp decline-slow increase-slow decline trend.The optimum ratio on the ash-sand ratio and coal ash content of similar-paste grouting materials were 0.6∶1 and 80%respectively.After adopting the technical scheme of anchor(cables)+paste grouting control for 30 days,the maximum subsidence of the roof was less than 80 mm,the maximum convergence of two sides was less than 70 mm,and the gateway surrounding rock was stable.