渗滤效应下砂土注浆加固机理试验研究

Mechanism Analysis of Sand Grouting Based on Percolation Effect

渗滤效应是砂土等多孔介质注浆过程中的普遍现象,渗滤效应对浆液流速、浓度及扩散距离均有显著影响.基于Darcy渗流定律、质量守恒方程及线性滤过定律,对渗透注浆中水泥颗粒的运移方程、浆液锋面速度及压力进行推导,分析了多孔介质渗滤效应的基本机理.采用矿渣、超细水泥进行了砂土注浆试验,发现水灰比、孔隙比及注浆压力等因素对渗滤效应均有显著影响.水灰比减小导致浆液浓度增加,水泥颗粒被滤出阻塞孔隙通道,浆液扩散终止;孔隙比减小砂土孔隙尺寸缩小,渗滤效应导致浆液扩散距离减小.而渗滤效应导致的浆液分布不均衡性,在一定程度上降低了注浆加固的效果.

Percolation effect is a common phenomenon in the process of grouting in porous media such as sand.Percolation effect has a significant impact on slurry velocity,concentration and diffusion distance.Based on Darcy’s seepage law,mass conservation equation and linear filtration law,the migration equation of cement particles,slurry front velocity and pressure in seepage grouting are deduced,and the fundamental mechanism of seepage effect of porous media is analyzed.The sand grouting test is carried out with slag and ultra-fine cement.It is found that the water cement ratio,void ratio and grouting pressure have significant effects on the percolation effect.The decrease of water cement ratio leads to the increase of slurry concentration,the cement particles are filtered out to block the pore channel,and the slurry diffusion is terminated.With the decrease of void ratio,the pore size of sand decreases and the seepage effect leads to the decrease of the slurry diffusion distance.The uneven distribution of slurry caused by seepage effect reduces the effect of grouting reinforcement to a certain extent.