水泥浆液在不同砂层内注浆扩散机制分析

Analysis of grouting diffusion mechanism of cement slurry in different sand layers

揭示水泥浆液在不同砂层内注浆扩散机制对于指导煤矿、地铁、公路等领域注浆加固砂质地层至关重要。采用自主研发的砂层注浆试验装置,通过1根注浆花管对2种不同颗粒级配的砂层同步注浆,探究水泥浆液在不同砂层内扩散形态之间的差异。研究结果表明:水泥浆液在颗粒级配较差的圆粒砂内发生渗透扩散,在颗粒级配良好的粗河砂中发生劈裂扩散。采用管道流模型和圆孔扩张理论分别阐述了渗透注浆和劈裂注浆2种扩散模式的力学机理,孔隙通道尺寸较大的土层,浆液启动压力梯度越小,在该种土层内浆液越容易发生渗透扩散。当注浆压力较大且孔隙通道尺寸较小时,会发生劈裂扩散模式,若土体发生张拉破坏,则劈裂浆脉平行于小主应力作用面;若土体发生剪切破坏,则劈裂浆脉与小主应力作用面的夹角为45°-φ/2。

Revealing the diffusion mechanism of cement slurry grouting in different sand layers is crucial for guiding the grouting reinforcement of sandy formations in fields such as coal mines,subways,and highways.Using a self-developed sand layer grouting test device,two sand layers with different particle sizes were synchronously grouted using a grouting tube to explore the differences in the diffusion morphology of cement slurry within different sand layers.The research results showed that cement slurry underwent infiltration diffusion in poorly graded round sand,while splitting diffusion occurred in well graded coarse river sand.The mechanical mechanisms of two diffusion modes,infiltration grouting and splitting grouting,were elaborated using the pipeline flow model and the circular hole expansion theory.For soil layers with larger pore channel sizes,the smaller of the starting pressure gradient of the slurry,the more likely it was to undergo infiltration diffusion in this type of soil layer.When the grouting pressure was high and the pore channel size was small,a splitting diffusion mode would occur.If the soil underwent tensile failure,the splitting grout vein would be parallel to the surface of small principal stress;If the soil underwent shear failure,the angle between the splitting grout vein and the surface of small principal stress was 45°-φ/2.