Analysis and engineering application investigation of multiple-hole grouting injections into porous media considering filtration effects

Abstract

The arrangement parameters of multiple grouting holes are important issues in soil sealing and in guaranteeing the grouting effectiveness. To better understand the effects of the arrangement parameters of multiple grouting holes, including the arrangement of the pass and space between the holes (the effective range of slurry diffusion and effective porosity of the injected media), on the effectiveness of grouting reinforcement, diffusion models of single-hole grouting and multiple-hole grouting are constructed based on fractal geometry and filtration effects. Then, the parameters of the grouting hole obtained by the present model are applied to the site. After grouting, the effect of grouting reinforcement under the corresponding parameters of the hole is obtained by analysing ground-penetrating radar data for the design profile and the porosity of each observation hole. The theoretical and engineering test results show the following responses: (1) The predictions from the proposed model show good consistency with the literature data and application results. For instance, in the case with filtration, the porosity increases faster at nearer distances, beyond which there is approximately no change in porosity with increasing distance. However, in the case without filtration, there is approximately no change in porosity with increasing distance during the whole process of grouting. (2) In the case without filtration, the effective diffusion range of the slurry depends only on the diffusion pressure of each test point. However, in the case with filtration, the effective diffusion range of the slurry depends not only on the diffusion pressure of each test point but also on the porosity of the injected media. (3) Under identical parameters of grouting hole and engineering geological conditions, the grouting expense of a triangular pass is less than that of a rectangular pass to achieve the same grouting effect.