Compaction grouting in the United States

Abstract

Compaction Grouting was initially developed in the 1950s in the United States as a method of rectification of settlement problems. It evolved due to the lack of control of slurry grouting for solving these types of problems. The key feature of Compaction Grouting was the injection of low slump, cementitious grouts under high pressure to densify problem soil strata. The next step on the development curve of this soil improvement technique was to counteract the settlement caused by soft ground and mixed faced tunnelling. Initially used on the Baltimore Subway System, it has subsequently been successful on many other major soft-ground tunnelling operations. On the Seattle, Washington Light Rail Transit, a major innovation was the use of non-cementitious grouts, to allow reinjection through the grout pipes, if any additional movement occurred. A large scale, fully instrumented test program verified that compaction grouting could densify potentially liquefiable soil beneath an existing, operating dam and developed design criteria, quality assurance, and a quality control program for the actual utilization beneath this and other potentially liquefiable sites. Improving the soil for new construction was the next development of Compaction Grouting; it was combined with Dynamic Deep Compaction to improve the soil beneath two new fossil fuel power generation plants in Jacksonville, Florida to allow construction on shallow footings. In a further project, the potential of contaminating an aquifer from the construction of a new landfill over karst topography was the basis for extensive laboratory and field tests. The resulting design procedure will be one of the standards for future compaction grouting programs. This paper will outline the development of Compaction Grouting in the United States and suggests research needs in Compaction Grouting technology. Introduction and history Remedial Minimizing settlements due to soft ground tunnelling Limestone cavity rectification Combined ground modification techniques Seismic protection New construction Conclusions References