Research On The Effectiveness Of The Sand Body Permeation Grouting

With rapid development of economy and infrastructure construction in our country, grouting technology has been widely used and playing an increasingly significant part in most underground engineering construction. Permeation grouting is one of the most widely used grouting technology currently, whose relevant fields concern about water conservancy and hydropower engineering, railway and highway engineering, cross sea traffic engineering and underground mining engineering, The technology is convenient for operating with little disturbance on surrounding rock, and has achieved good effects on solving sand and soil mass enhancement, seepage control and other problems. However, due to the complication of the internal structures of the sand and soil mass and the various factors influencing the grout seepage flow, study of grout penetration has been limited to the stage of empirical formula, causing the grouting theory fall behind engineering practice, which can hardly conduct grouting engineering.Aiming at those problems in the theory study and engineering application of permeation grouting, grout plugging mechanism under permeating effect was studied through theoretical analysis in this paper. In the meantime, model test was developed concerning grouting capability into sand and soil mass of different gradation and permeation grouting diffusion. At last, qualitative and quantitative relationship was discussed among various influencing factors, based on a combination of laboratory test and the verification of grout plugging mechanism under permeating effect.(1) Using Kozeny-Carman model and according to Darcy’s law and Ergun theory, seepage flow plugging mechanism of Newton fluid was studied based on permeation effect of particle grout, by which grout velocity, diffusing distance, diameters of seepage flow pipe and pressure reduction were obtained.(2) Grouting capability of sand and soil mass is a dominant factor of permeation grouting. Based on current theory of grouting capability, orthogonal test was carried out to study influence law on grouting capability of different factors, such as pore diameter of sand and soil mass, grout concentration and grouting pressure. Later on, regression analysis was conducted for each test statistics, thus obtaining quantitative relationships between grout diffusing radius and pore diameter of sand and soil mass, grout concentration and grouting pressure and carrying out a new evaluation criteria for grouting capability. (3) A new permeation grouting test device was developed independently, provided with a good feature of exact grouting pressure control, a large diversity of reception medium and a high accuracy of grouting effect feedback. Orthogonal test was carried out on different single-particle-sized sand samples and their mixture. With a combination of regression analysis, quantitative relationships was obtained between reinforcing strength of solid sand mass and pore diameters of sand and soil mass, grout concentration and grouting pressure. Variation law of reinforcing strength of solid sand mass and coefficient of permeability along diffusing distance was also studied.