Study of effective depth of high energy level dynamic compaction on backfilled residual soil

The study of effective depth of high energy dynamic compaction on sticky/sandy/gravel backfilled residual soil is based on the field test results of three large-scale projects. Effective depth of different high energy level dynamic compaction on three different backfilled residual soil and the relationship of them were determined based on bearing capacity and compression modulus before and after compaction which were determined by in-situ testing method such as load test, standard penetration test, dynamic penetration test, etc. Results indicate that under the same energy level of dynamic compaction, the higher the residual soil backfill ground gravel content is, the deeper the effective reinforcement depth becomes. Suggested formula of effective depth which soil nature and the energy level taken into account was obtained. Results also indicate that the recommended value in Chinese code is lower than the calculated value of the suggested formula.