Factors Affecting Long-Term Efficiency of Compensation Grouting in Clays

Compensation grouting has been attracting attention in recent years to control ground settlement caused by underground construction. A successful and effective application of compensation grouting depends not only on the use of a good monitoring system in the field but also on a fundamental understanding of grout behavior in soils. For compensation grouting in clay, there is a need to consider the long-term effectiveness of compensation grouting. Grout injection tests were conducted in the laboratory to examine soil fracturing patterns and consolidation effects in relation to compensation grouting. Both compaction and hydrofracturing modes of grouting were tested on kaolin clay specimens with different overconsolidation ratios. Finite-element analysis was also conducted to simulate the balloon expansion tests ~ideal compaction grouting tests! and the results were compared with the data from the laboratory tests. Based on the research findings, new design criteria are proposed to improve the long-term efficiency of compensation grouting for clays.