Low-vibration methods of soil compaction for urban utility projects : phase 2

This report presents the findings of the second phase of an exploratory project to assess the potential of nonvibratory methods of compaction for utility-related compaction needs. Proposed refinements and additions to existing compaction procedures are based on the use of an alternating flooding and vacuum procedure introduced through a pipe or series of pipes embedded in the soil. This process had been demonstrated in early Phase I laboratory tests to give better results than flooding alone for granular soils. Phase II laboratory and field tests produced compaction results ranging from an acceptable level of compaction to an unacceptable level. The flood/vacuum method appeared to work best in well-graded granular materials including some, but not an excessive amount of, fine particles. The cycle times for flooding and vacuum removal of the water appeared to be too long for practical use. The flood/vacuum technique by itself, or without reasonable levels of static compaction, does not appear to be a viable technique for field use. It appears that results from the technique could be significantly approved by adding mechanical disturbance of the backfill material or vibration energy to the flooding cycle.