Experimental Investigations On The Mechanisms Of Chemical Grouting In Transparent Soil

The objective of the present study is to understand the processes influencing the chemical grout, urea-formaldehyde resin grout, injection into porous media by using transparent soil. The experimental and numerical investigations were summarized as follows:A new transparent granular soil that consists of fused quartz particles in combination with a mixture of two mineral oils as pore fluid was proposed. The soil has important advantages with respect to transparency, stability, health safety, and utility over glass and silica gel materials. The transparent soil is also inexpensive compared to silica gel-fluid materials that have been used in the past. Two mineral oils from industry was tested and used as pore fluid. The oil has important advantages with respect to transparency, stability, health safety, and utility over calcium bromide.Conventional laboratory shear box, triaxial compression, and permeability tests were carried out to demonstrate that the mechanical properties and hydraulic permeability of the transparent soil are typical of granular soils with angular particles. A new shear box was modified by using Polymethyl methacrylate so that the face of this shear box was transparent. Furthermore, triaxial compression tests were carried out by using PVC heat shrinking film.An optical system consisting of an optical table, an extensible model frame, CCD cameras, a frame grabber, and a PC was developed to measure grout-water interface in transparent soil non-intrusively. A grout injection system consisting of a air compressor, pressure containers, proportional control valves, and pressure transducers was developed to simulate double line inject pump.Urea-formaldehyde resin with additives that can control the strength and setting characteristics of the injected liquid was used as chemical grout. Permeation grouting in both hydrostatics and hydrodynamics condition were investigated by using transparent soil model.Three CCD cameras were installed perpendicular to each other to acquire orthogonal images. A Matlab GUI program was developed to control three cameras at the same time. Camera calibration, which is a necessary step in 3D computer vision in order to extract metric information from 2D images, was carried out based on computer vision theory. A new model for image-based 3D reconstruction was proposed by using BPLI parallel contours. Meanwhile, a Matlab GUI program was developed to reconstruct grout-water surface.The result shows that the lower boundary of grout-water interface tends to sink under gravity in hydrostatics condition. However, the gravity was ignored in classical Maag’s equation. As a result, a modified equation with gravity based on Maag’s equation was proposed. A numerical model based on FEM was developed in COMSOL Multiphysics to verify the modified equation.Peristaltic pumps and water flow Hall’s effect s ensors were installed in transparent soil model to precisely control water flow in hydrodynamics condition. The result shows that the grout-water boundary was moved along the groundwater flow direction.A piston type model box was applied to simulate high confining stress in soil fracture grouting. The results indicate that the shape of fractures differs from that in clay. Without any “fingers” fracturing in the sand, heave is very local and compaction of the sand may occur. Fracture injection pressure was introduced by the cavity expansion theory.