砂性土层注浆过程中浆液滤过特性及其评价方法研究

Grouting has become an important means of soil reinforcement and compensation. It has been widely use in sandy soil. During grout dispersion process in sandy soil, the cement grains are progressive filtered by the solid skeleton, resulting in the progressive blocking of the soil matrix and the increasing of the grouting pressure, which is named as filtration effect. The filtration of grout plays a significant role during grouting process in sandy soil. Cement grout is a kind of two-phase fluid in engineering. Based on this, we hope that this research benefits the study on the effect of filtration and understand of the effective factors of filtration. The grade standard of injectability based on filtration effect and evaluation method of filtration will be given. A cement grout dispersion model with account for filtration will be proposed. The key issues and the conversion condition during the conversion process from permeation grouting to compaction grouting will be analyzed. The model of pressure filtration considering the changes of permeability and the model of compaction grouting considering the effects of seepage pressure of the soil will be obtained. The research can provide guidance on the grouting in sandy soil.

土体注浆已成为土体加固、土体损失补偿的重要手段，特别在砂性土层中，得到了大量的应用。在砂性土层的注浆过程中，水泥颗粒由于土颗粒骨架的阻拦作用会逐渐滤出，造成土体孔隙阻塞，注浆难度增加，称之为滤过效应，滤过效应在浆液扩散过程中起着非常重要的作用。本课题希望能考虑水泥浆悬浊液的二相特性，深入分析滤过效应对砂性土层注浆的影响，弄清影响浆液滤过特性的关键因素，建立以为滤过效应基准的土体可注入性等级评价标准，给出注浆过程中浆液滤过特性的合理评价方法，建立以建立考虑滤过效应的浆液扩散理论，并对由于滤过效应造成的渗透注浆向压密注浆转化过程中的关键问题进行分析，弄清部分滤过到完全滤过（压滤）的转化条件，建立考虑土体透水特性改变的浆液压滤模型，建立考虑透水土体的压密注浆模型。从而为砂性土层中注浆的分析和应用提供指导。

土体注浆已成为土体加固、土体损失补偿的重要手段，在工程中得到了广泛的应用。浆液注入过程中的滤过效应是影响浆液扩散的重要因素，水泥颗粒在注入过程中会被土颗粒骨架逐渐滤出，造成土体孔隙阻塞，注浆难度增加，影响浆液的加固作用。本课题从水泥浆液的悬浊液二相特性出发，研究了水泥浆液注入后与土体的相互作用，分析了滤过效应对砂性土层注浆的影响，研究了影响浆液滤过特性的关键因素，研究表明水泥浆液的滤过是非线性过程，受土体可注入性、浆液浓度等因素的影响，当土体渗透性达到临界值时，浆液的滤过逐渐转为压滤，浆液的压滤分为线性压滤阶段和非线性压滤阶段，由浆液浓度和界面水泥层厚度控制，当达到临界值时，压滤逐渐转为压密。同时本课题对不同滤过、压滤条件下浆液对土体的加固作用进行了研究，基于研究结果给出了砂性土层考虑滤过效应的浆液扩散评价方法以及土体加固评价方法，可为砂性土层中注浆的分析和应用提供指导。