Visualization of Chemical Grout Permeation in Transparent Soil

Abstract This paper presents an experiment that visualizes the permeation of chemical grout in transparent soil. The low initial viscosity (5 mPa · s) urea-formaldehyde resin (UFR) was chosen as grouting material in this experiment. The transparent soil used in this study is made of fused silica and a calcium bromide solution with the same refractive index. Triaxial and permeability tests are carried out to demonstrate that the geotechnical properties and hydraulic permeability of this transparent soil are typical of granular soils and suitable for modeling natural sand in permeation problem. A combined grouting and optical measurement system is developed for this study, which consists of an air pressure driven grout injection station to inject grout into a transparent soil model, laser to illuminate the cross-section of interest inside the model, and a charge-coupled device (CCD) camera to capture a series of images during the whole grout injection and permeation process. Image processing techniques including digital image correlation (DIC) are applied to sequence of images to detect the edges of the grout bulb and displacement distribution. The relationship of the grouting radius and grouting time corresponds to Maag's formula on permeation grouting. As a result, the validity of this innovative experiment has been verified.