Calibration chamber modeling of compaction grouting

Compaction grouting, despite its many applications, has some problems that are basically attributed to the minimal guidelines to predict treatment effectiveness and the relatively little understanding of grouting mechanisms. To physically model and investigate compaction grouting in the laboratory under controlled conditions, large-scale calibration chamber, sand deposition, and injection systems have been developed. The chamber that has been developed is of the double-wall type and can independently control the sample stresses and deformations and impose different boundary conditions. Compared to the available double-wall chambers, the developed chamber has several innovative features. It is larger in size and self-reacting, applies the vertical stress at the top of the sample, provides for a rigid boundary at the base of the sample, and provides for upheave of the sample surface. The developed sand deposition system adopts the principles of pluvial deposition through air to prepare uniform soil samples at controlled relative densities. The developed injection system can inject actual compaction grouts. The developed systems are described in this paper. Some typical testing results are also presented and discussed to assess the chamber performance and illustrate the corresponding grouting mechanisms. The results reveal satisfactory performance of the developed systems and proper modeling of compaction grouting.