考虑黏度空间衰减的宾汉姆流体柱形渗透注浆机制研究

Study on the mechanism of column permeation grouting of Bingham fluid considering the spatial attenuation of viscosity

低渗透性多孔介质渗透注浆过程中存在渗滤效应,造成浆液颗粒浓度和黏度空间分布不均,严重影响注浆效果。通过一维可视化注浆试验,研究渗滤效应的发生条件及影响因素,得到考虑水灰比影响的黏度衰减率空间分布表达式,并推导出考虑黏度空间衰减的宾汉姆流体柱形渗透注浆理论公式,基于计算机编程技术,依托Comsol Multiphysics平台,二次开发得到该理论公式的二维数值模拟程序,在此基础上开展不同注浆压力和水灰比条件下的仿真分析和模型试验,对比验证该理论机制的正确性。研究结果表明,渗滤效应发生时,浆液颗粒浓度和黏度沿渗流路径明显下降,采用考虑黏度空间衰减效应的宾汉姆流体柱形渗透注浆扩散公式得到的扩散半径、渗透压力等更接近实测值。因而更好地说明渗滤效应导致的黏度空间衰减不可忽略,采用新的理论公式更能反映宾汉姆流体在低渗透性地层中发生渗滤效应时的扩散规律。该研究成果可为低渗透性地层注浆设计及施工提供一定的理论及技术支持。

Infiltration effect exists in the process of low permeability porous media infiltration grouting,resulting in uneven spatial distribution of slurry particle concentration and viscosity,which seriously affects the grouting effect.Through one-dimensional visual grouting test,the occurrence conditions and influencing factors of percolation effect were studied,and the spatial distribution expression of the viscosity attenuation rate considering the influence of the water-cement ratio was obtained,and a theoretical formula of Bingham fluid column seepage grouting considering the spatial attenuation of viscosity was derived.Based on computer programming technology and relying on Comsol Multiphysics platform,the two-dimensional numerical simulation program of the theoretical formula was obtained by the secondary development.On this basis,the simulation analysis and model test under different grouting pressures and water-cement ratios were carried out to verify the correctness of the theoretical mechanism.The results show that the concentration and viscosity of grout particles decrease obviously along the seepage path when the seepage effect occurs,and the diffusion radius and permeability pressure obtained by adopting the Bingham fluid column seepage grouting diffusion formula considering the spatial attenuation effect of viscosity are closer to the measured values.Therefore,the spatial attenuation of viscosity caused by percolation effect cannot be ignored,and the new theoretical formula can better reflect the diffusion law of Bingham fluid when percolation effect occurs in low permeability strata.The research results can provide theoretical and technical support for grouting design and construction of low permeability strata.