富水破碎岩体帷幕注浆模型试验研究

利用自主研制的三维注浆模型试验系统,开展富水破碎岩体多孔分序帷幕注浆试验,获得注浆扰动下岩体多物理场演化规律:1被注岩体总压力及孔隙水压力变化强烈,历经急剧增长—峰值波动—渐进衰减—趋于稳定的变化阶段;2破碎岩体内部,浆液在隧洞拱顶和拱底位置发生优势劈裂扩散,同时引起洞周收敛位移;3注浆作用下破碎岩体压缩释水导致渗透性能显著降低,表现为分序注浆试验中超孔隙水压力激发程度逐次大幅提高。帷幕注浆试验结束后,揭露、分析了加固体内部特征,研究破碎岩体加固范围非均匀变化规律,归纳总结松散破碎岩体及泥质软弱岩体对应的渗透–劈裂型及微劈裂型两类注浆加固模式,揭示了劈裂浆脉形成的多重注浆叠加机制。基于以上研究工作,利用扫描电子显微镜(SEM)分析固结岩体微观特征,研究表明浆脉–黏土界面具有三维结构,可划分为渗透型和微劈裂型两种类型,网络状微型浆脉的锚固作用增大了界面粗糙度和强度;界面靠近黏土一侧发育损伤裂纹,推测为固结岩体物理力学条件突变位置,为加固岩体潜在破坏环节。研究成果补充和完善了室内注浆模拟试验方法,探索了多孔分序帷幕注浆试验中浆液扩散规律及注浆加固机理,为类似地质环境下岩体注浆提供了理论支撑与技术指导。

Model tests on curtain grouting in water-rich broken rock mass

The multiple drillings and sequenced curtain grouting experiment for water-rich broken rock mass is carried out using self-developed 3D grouting model test system. The spatio-temporal characteristics of total pressure, pore pressure and displacement are obtained by the optical fiber parallel real-time monitoring system. The total pressure and pore pressure greatly change and have 4 periods: rapid growth, peak-value fluctuation, progressive attenuation and gradual stability. The slurry advantage-fracture diffuses in the vault and arch bottom, leading to displacements around the tunnel. The permeability decreases because of compression and consolidation of the grouted rock mass, and the pore pressure is significantly improved during sequent grouting. After the grouting experiment, the reinforced body is exposed and its irregular form is studied. The penetration-splitting grouting reinforcement model for broken rock mass and the splitting grouting reinforcement model for argillaceous weak rock mass are summarized. The mechanism of repeated grouting of splitting grouting veins is revealed. The SEM images of grouting-reinforced body reflect that the interface between grouting vein and clay can be divided into penetrating type and split type, and the micro slurry veins improve the surface roughness and strength. A fractured crack develops to be closer to the clay, which suggests that physical and mechanical saltation takes place over there, which is the potential broken link of reinforced rock mass. The research improves the grouting experiment method and explores the slurry diffusion laws and grouting reinforcement mechanism, thus providing technical support for grouting management under similar conditions.