Grouting Mechanism Based On Filtration In Porous Media With Cement Grout And Its Engineering Application

Grouting technique is a highly specialized academic branch of geotechnical engineering. In the process of operation, filling and cementation of grouting material are conducted for use of the consolidation of injected structure and water plug, as well as the modification of hydro-geological and engineering geological conditions, which is widely used in the special geological disaster governance of tunnel, mining and hydroelectric power station and other underground engineering, and also achieves remarkable effect. In the mean time, the investigation and application of grouting theory, construction technology and grouting material are developing rapidly, which generate an extensive variety of grouting material and its properties. In these materials, cement grout is composed of cement as main part, which contains Portland cement grout, sodium silicate cement grout and cement based polymer modified grout, which is widely used due to its merits of economy and friendly environment.Portland cement grout, which belongs to particle grout, was investigated on the aspect of porous media filtration, which has not been paid much attention to. This study mainly focuses on its deep bed filtration during penetration. Based on the common quick-setting cement grout, sodium silicate cement grout and cement based polymer modified cement grout, viscosity of time-dependent behavior test experiment is conducted, and the two kinds of grout viscosity time-varying characteristic and its engineering application are analyzed. On the basis of the results, the function relation between the grouting quantity and the pore diameter of the porous media, the grout concentration as well as the grouting pressure was obtained by regression analysis. Sand samples of different particle size were selected to conduct one dimensional long-column-type penetration test. Time-varying law of penetration pressure during grouting was studied with the consideration of the deep bed filtration effect. The influence of the deep bed filtration on grouting effect was analyzed. Theory of deep bed filtration of porous media was investigated. Two assumptions were adopted as follow:f(a)=1and the grout concentration is constant. With a combination of results, the pressure variation during grouting was analyzed, and the accuracy of the two assumptions was testified through comparison and analysis. On the basis of the study of filtration effect, the grouting capability can be divided into three stages. Influence of the filtration effect of the grout particles on the grouting mechanism in different stages was analyzed.Three dimensional grouting model testing system was established. Sand grouting penetration test using cement slurry was conducted. The change law of the two parameters was obtained, by monitoring the penetration pressure and the soil pressure during grouting. Grouting spread characteristics was analyzed, and the horizontal distribution of the compressive strength was obtained by coring consolidation mass in different position and testing its compressive strength.In combination with high pressure and large flow gushing water treatment project in fracture zone of zhongliangshan tunnel, makes an analysis of the different mechanical properties, viscosity properties of grouting material, construction control, gushing water plugging performance and surrounding rock stability influence, comprehensive evaluation on the applicability of grouting material, has a certain reference significance for similar projects.