Finite Element Modeling of Compaction Grouting on its Densification and Confining Aspects

Compaction grouting method called as CPG is becoming popular as a ground improvement technique due to its wide variety of applications and several advantages. However, so far, the application of the method has been mainly dependent on field tests, practical experience and empiricism. This paper presents a 2-D finite element model of CPG based on the elasto-plastic theory of strain hardening that takes variations in stress–strain fields along the depth and the impact of the ground surface conditions on the grouting process. This reveals densification and confining aspects of CPG with relative contribution of variables like injection pressure, spacing of injection points, overburden pressure and initial relative density of ground. This paper concludes that the ground improvement by CPG should not be taken as increased ground density alone but also as increased lateral earth pressure. Although no densification can be achieved for medium or dense soil, CPG process is found to be effective in increasing the lateral earth pressure of medium or dense soil significantly. The lateral earth pressure increases with increase in injection pressure only up to the some extent but with further increase in injection pressure its effect reaches to the farther radial distances.