Study on grouting performance in sandy soils

Abstract

Construction activities are involved with improvement of soil where the building or structure is built on weak zone. Grouting is one of effective methods to enhance soil structure by hydraulic soil cracking and filling with grout materials. The weak zone can exist around tunnel excavation sites or foundations and among others, and can be improved by injecting grouting materials. The effect of grouting is to reduce the permeability of soil media to densify the week soil, and to fill up the voids with grouts. The grouted zone serves as stabilization areas adjacent to the tunnels and sealing against inflow. Naturally, the formation and development of hydraulic fracturing much depend on geologic factors, grouting materials and grouting process. It is necessary to figure out conditions and circumstances in which hydraulic fracture happens and the initiation and the propagation process of hydraulic fracturing in particulate materials. In order to do so, fracture characteristics must be considered and well studied. Main fracture types considered herein are "sheet" and "bulging" fractures. Another type of fracture is an intermediate type which plays as an intermediate role between them. This type is important because it is a reference to differentiate two types. The mechanisms that govern the formation of fractures are very important because we can control them if the behavior of fractures is well understood. Moreover, we need to study and control the factors that affect the hydraulic fracturing process. The main purpose of this thesis is to analyze and summarize influential factors in hydraulic fracturing that can affect the types of hydraulic fractures. A small-scale laboratory experimental model is suggested using the modified consolidometer. Base materials used in the tests are sandy soils. In experiments, several types of grouting materials are used for injection. After each test, the injected material is preserved and analyzed. Viscous fluids are grouted into th...