Briefing: Dry bottom-feed stone column construction in soft fine-grained soils

Increasing pressure to develop marginal soft clay sites, combined with increasing emphasis on environmentally sensitive and sustainable vibro ground improvement solutions, has seen significant advances in the use and application of the dry bottom-feed vibro stone column technique. It is clear, however, from the observations made during field trials of partial-depth vibro stone columns at the (former) Bothkennar soft clay research site in Scotland, that appropriate consideration needs to be given to stone column construction using the dry bottom-feed method in soft, sensitive, fine-grained soils, in order to minimise disturbance effects and optimise performance. Some of the more significant observations made, together with some suggested best practice guidance on stone column construction using the dry bottom-feed method, are outlined; some potential further research opportunities are also suggested.