帷幕灌浆扩散半径及数值模拟的研究

从连续性方程出发，考虑浆液压力对土体孔隙率的影响，分析推导了浆液在多孔介质中的渗流规律，并给出了扩散半径的简单近似计算公式；然后将二相流理论应用到注浆研究中，假设孔隙由水和浆液完全充填，且二者不相混溶，建立了浆液驱水的非稳定渗流模型。根据某大坝的实际情况，用FLAC软件中的二相流模块对大坝灌浆过程进行了模拟分析，并与推导公式相比较。由于二相流理论考虑了毛细压力的作用，模拟得到的浆液扩散速率递减得更快。模拟结果表明，浆液和水之间存在着一个过渡带，浆液的饱和度在不同时间和位置上是变化的。随着时间的延长，浆液扩散得越远，但其速率逐渐减小。扩散半径不仅与渗透系数有关，还与孔隙度有关，而且孔隙度较渗透系数对扩散半径有着更大的影响。二相流理论可以更好地模拟帷幕灌浆的浆液扩散情况。

Research on diffusion radius and numerical simulation in curtain grouting

Considering the effect of grouting pressure on soil porosity,the grout flowing law is analysed and deduced from continuity equation in porous medium.The simple approximate formula of diffusion radius is obtained.Then two-phase theory is applied to grouting research.With the hypothesis that soil pores are filled with water and grout and they are immiscible,unsteady flow model of grout driving water is established.The solving key lies in getting the relations between relative permeability,capillary pressure and porosity.Two-phase flow module in FLAC software is used to simulate grouting process of a certain dam;and the results are compared with the deduced expression.These two results are approaching in the initial stage.But because of considering capillary pressure,the diffusing rate using two-phase theory decreases faster.The simulation results show that there is a transitive area between grout and water.Grout saturation is varied with time and space.As the time passing,grout permeates farther,but the rate becomes slow gradually.Diffusion radius is not only related with permeability coefficient but also with porosity;and porosity has more influence than permeability coefficient.The greater permeability coefficient makes grout flow faster and the larger porosity lets grout flow farther.Two-phase theory is better to analyse the permeating regularity.