Purpose and Procedure: Sonic core sampling is similar to direct-push macrocore sampling in that is provides a continuous, variably undisturbed sample. However (depending upon the size of core barrel used), sonic drilling typically provides a much larger sample volume and can sample coarse-grained soils without excessive particle bias and/or sample refusal. The soil core is collected directly inside of the core barrel as the drill stem is advanced using a combination of: high-frequency vibratory action; rotational drilling, and hydraulic down pressure. Upon retrieval from the borehole, the core barrel sampler is vibrated to extrude the sample into large tubular plastic bags, which can then be cut-open to expose the soil sample for geotechnical classification and logging and laboratory sample collection.
Pros:
- Collects a relatively large sample volume
- Relatively fast sample collection
- Can effectively sample coarse-grained soils
- Generates limited drill cuttings
Cons:
- Collects a disturbed sample
- Can be difficult to effectively sample permafrost or competent bedrock
- Comparatively expensive to other sampling methods
- Limited availability in Alaska
