砾岩含水层帷幕浆液运移规律与改性效果分析

注浆帷幕截流是深部矿井水害治理的主要技术手段之一,针对淮北矿区朱仙庄煤矿8号煤层水害防治问题,采用CT扫描与室内试验测试得到受注砾岩孔裂隙分布及岩石力学特征,利用COMSOL Multiphysics软件建立了受注砾岩层的孔隙介质与孔隙-单裂隙介质2种数值模型,分析了帷幕墙注浆截流效果。研究结果表明:浆液在孔隙介质中的运移范围随注浆时间的增加而增大,浆液运移稳定后的扩散范围为10.12～10.44 m;孔隙-单裂隙介质数值模型中,浆液运移形态沿裂隙方向对称,浆液运移优先进入裂隙通道,随后沿裂隙方向扩散至孔隙介质中,随注浆时间的增加,浆液运移范围逐渐增大并最终趋于稳定,孔隙-单裂隙介质中浆液的纵向扩散范围为10.05～10.23 m,横向扩散范围为16.30～16.98 m;根据数值计算结果,提出了注浆孔间距为20 m、两排注浆孔交错布置、有效宽度约为40 m的帷幕截流方案。最后,通过注浆前后砾岩物理力学性质对比分析与现场放水试验的方法,验证了帷幕墙截流效果良好、注浆孔间距布置合理。

Transport law of curtain grouting fluid in conglomerate aquifer and evaluation of rock mass modification effect

Grouting curtain closure is one of the main technical means for deep mine water damage control.The objective of this study was to solve the mine water damage problems in No.8 coal seam of Zhuxianzhuang coal in Huaibei mining area.The CT scan and laboratory test were used to obtain the fracture distribution and rock me chanics characteristics of the conglomerate.In addition,two numerical models of pore media and pore single fracture media in the conglomerate layer were established using COMSOL Multiphysics software.Also,the grouting curtain closure effect was analyzed.The results show that the range of slurry transport in the porous medium increases with the increase of grouting time,and the diffusion range of the stabilized slurry is 10.12-10.44 m.In the pore single fracture medium,the slurry preferentially enters the fracture channel and then diffuses into the pore medium along the fracture direction.With the increase of grouting time,the slurry transport range gradually increases and eventually stabilizes.The longitudinal diffusion range of slurry is 10.05-10.23 m,and the transverse diffusion range is 16.30-16.98 m.According to the numerical calculation results,20 m is selected as the spacing of grouting holes in the site curtain grouting project,two rows of staggered grouting holes are arranged,and the curtain wall with an effective width of about 40 m is established.Finally,with the comparative analysis of physical mechanical properties of conglomerate before and after grouting and the method of on site water release test,it is verified that the curtain wall closure effect is good and the spacing of the grouting holes is reasonable.