含单一贯通破裂面岩石注浆试验及加固机制分析

Grouting test and reinforcement mechanism analysis of rock with single penetrated fracture surface

针对单一贯通结构面注浆加固影响围岩承载力的问题,提出了一种制作含单一贯通破裂面岩样的方法,并对此种岩样分别注入超细水泥和环氧树脂材料,进而借助RMT-150 C试验系统探究了固结体单/三轴压缩下强度及变形特征,最后,采用理论分析结合电镜扫描手段,揭示了结构面注浆微观固结机制。研究发现,三轴加-卸载条件下制备的破裂结构面更接近工程实际,符合试验要求;从应力-应变特征曲线来看,注超细水泥试件表现出阶段性,注环氧树脂试件曲线较为平滑;从强度特征来看,围压影响程度明显高于注浆材料的选择;注浆加固手段可提高岩体的残余强度,随着围压的提高,残余强度提高系数越不明显,固结体峰值强度愈发接近完整岩石峰值强度;从破坏特征来看,注超细水泥试件主破裂面沿原始破裂面剪切滑移,注环氧树脂试件主破裂面为新的贯通破裂面;最后,以摩尔-库仑准则为理论基础,建立了注浆材料黏结力与结构面强度提高系数关系式,发现结构面强度提高系数与浆液黏结力呈线性关系。与试验结果的对比表明,该公式较为合理,可为深部围岩支护优化提供参考。

For the problem that how the grouting reinforcement of a single penetrated structural plane affects the bearing capacity of surrounding rock, an approach of making rock samples with single penetrated fracture surface is proposed firstly, and the rock samples are injected with ultra-fine cement and epoxy resin, respectively. Then, the strength and deformation characteristics of the consolidated body under uniaxial(triaxial) compression are investigated with the RMT-150C experimental system. Finally, the micro consolidation mechanism of structural plane grouting is revealed by means of theoretical analysis and electron microscope scanning.It is found that the fracture surface generated under triaxial loading-unloading condition is closer to the engineering practice and meets the experimental requirements. The stress-strain characteristic curves of the specimens injected with superfine cement show phased deformation characteristics, and the curves of the specimens injected with epoxy resin are relatively smooth. For the strength characteristics, the influence of confining pressure is significantly larger than that of grouting material selection. Grouting reinforcement can improve the residual strength of rock mass. With the increase of confining pressure, the increase of improvement coefficient of residual strength is less obvious, and the peak strength of consolidated body is closer to that of intact rock. For the failure characteristics, the main fracture surface of the specimen injected with ultra-fine cement shears and slips along the original fracture surface, and the main fracture surface of the specimen injected with epoxy resin is a new penetrated fracture surface. Finally,based on the Mohr-Coulomb criterion, the relationship between the bonding force of grouting materials and the strength improvement coefficient of structural plane is established. It is found that the strength improvement coefficient of structural plane has a linear relationship with the bonding force of grout. The comparison between calculation and test results shows that the formula is reasonable and can provide reference for the optimization of deep surrounding rock support.