富水弱胶结砂岩破坏特性与优化措施

敞开式TBM以其“速度快、强度低、效益好”等特点愈发在地下工程施工中得到广泛应用,同时随着我国加大西部地区基础设施和能源的开发力度,施工过程中将面临越来越多弱胶结砂岩地层,在该地层应用敞开式TBM难度极大,施工中经常发生冒顶、片帮、撑靴力不足的情况。为了早日投产,可可盖煤矿将在全世界范围内首次应用敞开式TBM进行斜井掘进,针对施工中穿越洛河组地层围岩强度低、胶结弱、涌水量大的情况,在已有研究基础上,借助现场实测、室内试验等多种研究手段,对洛河组富水弱胶结砂岩矿物成分及含量、孔隙结构等物理特性及微观结构进行了研究。试验结果表明该组岩层孔隙率达到25.6%,透水性强,且含有15%左右的粘土矿物,具有一定膨胀性,建议注浆时采用超强渗透性的纳米级注浆材料,改善注浆效果。在此基础上进行了不同含水率、不同围压下的三轴压缩试验,试验结果表明提高径向应力对控制围岩具有明显效果,创新性提出了“超前加固+锚网索+纳米级浆液注浆”的支护优化措施,数值模拟与现场应用结果表明优化后围岩破碎变形得到显著改善,实际掘进速度从10m/天提高到17m/天,极大提升了掘进效率与安全性。

Failure characteristics and optimization measures of weakly consolidated sandstone with rich water

Open TBM, known for their characteristics such as high speed, low impact, and excellent efficiency, are increasingly being widely applied in underground construction. However, as China intensifies its efforts in developing infrastructure and energy projects in the western regions, construction processes are encountering more and more weakly cemented sandstone formations. The application of open TBM in these formations presents significant challenges, often leading to issues like roof collapses, sidewall instability, and insufficient ground support. To expedite production, the Kekegai coal mine is planning to use open TBM for inclined shaft excavation, marking the first such application worldwide. Given the low strength, weak cementation, and high groundwater flow in the Luohe Formation, extensive research has been conducted, building upon previous studies. Various research methods, including field measurements and laboratory tests, were employed to investigate the physical properties, microstructures, mineral composition, water content, and pore structure of the water-rich, weakly cemented sandstone in the Luohe Formation. The test results indicate that the porosity of this formation reaches 25.6%, with strong permeability, and contains approximately 15% clay minerals, suggesting some expansiveness. It is recommended to use ultra-permeable nanometer-grade grouting materials to improve grouting effectiveness. Subsequently, triaxial compression tests were conducted under different moisture content and confining pressure conditions, demonstrating that increasing radial stress has a significant effect on controlling the surrounding rock. Innovative support optimization measures were proposed, including "advance reinforcement + anchor cable mesh + nanometer-grade slurry grouting." Numerical simulations and field applications have shown a significant improvement in rock fragmentation and deformation after optimization, resulting in an increase in the actual excavation rate from 10 m/d to 17 m/d, greatly enhancing excavation efficiency and safety.