考虑软化效应的全风化花岗岩地层三阶段注浆扩散机制研究

Study on Three-stage Grouting Diffusion Mechanism in Completely Weathered Granite Strata Considering Softening Effect

在全风化花岗岩地层注浆过程中,浆液中的水相在注浆压力和岩土边界的约束条件下存在软化效应,致使浆液在渗透-挤密-劈裂三阶段扩散过程中均受到不同程度的影响。为此,首先明确全风化花岗岩地层注浆扩散过程中的软化效应,探讨软化效应对全风化花岗岩地层注浆扩散的影响机制;其次建立考虑软化效应的全风化花岗岩注浆浆液三阶段扩散理论模型,并开展物理模型试验论证理论模型的可行性;最后将研究成果应用于广州地铁18号线注浆工程实践中。研究结果表明,软化效应伴随整个全风化花岗岩地层注浆过程,理论推导与物理模型试验结果误差小于20%,推导的理论模型可行;现场注浆效果表明,岩芯土体的无侧限抗压强度均大于0.8 MPa,隧道开挖后,掌子面稳定且形成了延展性较好的主干浆脉与分支浆脉,后续开挖过程中未发生灾害事故。

During the grouting process in completely weathered granite strata,the water phase in the grout undergoes a softening effect under the constraints of grouting pressure and geotechnical boundaries,which affects the grout diffusion in the three stages of penetration,compaction,and fracturing to varying degrees.This study first clarifies the softening effect in the grouting diffusion process in completely weathered granite strata and explores its impact mechanism.A theoretical model for three-stage grout diffusion in completely weathered granite strata considering the softening effect is established.The feasibility of this theoretical model is then validated through physical model experiments.Finally,the research results are successfully applied in the grouting project of Line 18 of the Guangzhou Metro.The results show that the softening effect accompanies the entire grouting process in completely weathered granite strata,with the error between theoretical derivation and physical model test results being less than 20%,proving the feasibility of the derived theoretical model.The on-site grouting results indicate that the unconfined compressive strength of the rock core soil is greater than 0.8 MPa.After tunnel excavation,the working face remains stable,forming a main grout vein and branching grout veins with good ductility,and no disaster accidents occurred during subsequent excavations.