基于模型试验的劈裂注浆机制分析

Analysis of fracture grouting mechanism based on model test

依托钟家山隧道帷幕注浆工程,设计了一套大比例劈裂注浆模型试验装置,模拟断层破碎带劈裂注浆过程,通过布设监测元件记录,分析注浆过程关键参数的变化规律,通过开挖充填介质直观揭露浆脉分布特征。试验发现,注浆过程中土体劈裂压力呈现类似脉冲状变化规律,试验条件下土体启劈压力Po=0.12 MPa,与现有理论解进行了对比分析。基于浆液扩散形式转换、主次生劈裂通道饱和、新劈裂通道形成和后续次劈裂区域饱和4个阶段,分析了土体劈裂压力变化机制,提出了主、次生劈裂压力值界定方法,并对试验条件下7次主劈裂压力值、53次次生劈裂压力值进行了分析,发现主劈裂压力值呈递增规律。结合P-t曲线从能量角度将劈裂过程划分为土体劈裂能量积聚、劈裂和浆液能量转移3个阶段,通过开挖充填介质揭露浆脉的空间分区域分布规律和主、次生浆脉共存规律并分析其成因,在钟家山隧道帷幕注浆工程进行现场应用试验,进一步验证了试验结论的正确性。试验结论对于注浆理论的认知和注浆工程的应用有一定的指导作用。

Based on the curtain grouting engineering of Zhongjiashan tunnel, a large-scale model test device is designed to simulate the process of fracture grouting in fault fracture zone. The variation law of key parameters during the grouting are recorded and analyzed by layouting monitoring components, and the distribution of grouting veins are exposed intuitively by excavating the filling medium. The test results show that the fracturing pressure presents a pulse-like law during the grouting process, and the first fracturing pressure under the conditions of this test is 0.12 MPa which is made a comparative analysis with the existing theoretical solution. The change mechanism of fracturing pressure is analyzed based on the conversion of slurry diffusion form, saturation of primary and secondary fracturing channels, formation of new fracturing channels and saturation of the follow-up fracturing zone. The definition methods of primary and secondary fracturing pressure are proposed; then 7 primary fracturing pressure and 53 secondary fracturing pressure under the conditions of this test are found to show an increasing law approximately. Based on the p-t curve, the fracturing process of soil are divided into 3 stages including the energy accumulation, soil fracturing and slurry energy transfer from the perspective of energy dissipation. The spatial distribution law and coexistence law of primary and secondary grouting veins are found by excavating the filling medium. The site application test is carried out in curtain grouting engineering of Zhongjiashan tunnel to verify the correctness of test results. The test results play a guiding role on the understanding of grouting theory and the application of grouting engineering to some extent.