Pressure grouting method can significantly enhance the strength of soil, and is widely used in foundation reinforcement. There already have some theoretical studies on pressure grouting, but the actual diffusion process of grouting can not be reflected exactly. Firstly, this paper conducts a field permeation grouting test on undisturbed loess of late pleistocene of quaternary, and acquires the pressure effected relationships of quantity vs. time. The test reveals that the grout quantity approximately increases linearly with the pressure until a certain grouting time point. The time point increases with grouting pressure and we try to define the pressure effected time point as the effective grouting time. After the effective grouting time, the grouting quantity remains constant due to the approaching of max migration radius and the stopping of grout migration. And then, considering the piston-like displacement effect of grout on porous mediums due to pressure, this study introduced the effective grouting time into the theoretical derivation process based on porous mediums’ fluid percolation pore pressure equation and Darcy’s law. The author combined the initial conditions and boundary conditions of pore pressure with the continuity conditions of permeation velocity, and performed the Boltzmann’s transformation and reduced-order processing to derive the equation for the migration velocity of the grout front and the migration radius of grout. Finally, by substituting the effective grouting time and the effective grouting quantity into the equation, we could obtain the grouting reinforcement radius. The equation can accurately predict the actual grouting reinforcement radius, and the applicability of the equation is verified by verification test.

压力注浆法可显着提高土体的强度，广泛用于地基加固。已有一些关于压力注浆的理论研究，但不能准确反映注浆的实际扩散过程。首先，本文对第四纪晚更新世原状黄土进行了现场渗透灌浆试验，得到了压力影响量与时间的关系。试验表明，在某个灌浆时间点之前，灌浆量大致随压力线性增加。时间点随着注浆压力的增加而增加，我们尝试将压力影响时间点定义为有效注浆时间。有效灌浆时间过后，由于接近最大迁移半径和浆液迁移停止，注浆量保持不变。然后，考虑到注浆由于压力对多孔介质的活塞式位移效应，本研究将有效注浆时间引入到基于多孔介质流体渗流孔隙压力方程和达西定律的理论推导过程中。作者将孔隙压力的初始条件和边界条件与渗透速度的连续性条件相结合，进行玻尔兹曼变换和降阶处理，推导出浆液前沿迁移速度和浆液迁移半径的方程。最后，将有效注浆时间和有效注浆量代入方程，我们可以得到注浆加固半径。该方程能够准确预测实际注浆加固半径，并通过验证试验验证了该方程的适用性。