Andrews Survey are now offering heavy-duty hydraulic vibrocorers for continuous, relatively undisturbed samples of 6m plus in length.
Developed for marine aggregates surveys, the vibrocorers can overcome penetration problems often encountered when sampling firm-to-stiff clays and silts, dense sands, sandy gravels and weathered bedrock. Each has up to five times the power of standard or higher-powered electrical corers and vibration times are often less than 1min for 6m samples.
The corers use standard barrels from 2m to 6m in length to produce 84mm cores. With modifications to the standard system, penetration can be increased to 10m. Despite its penetration power, the hydraulic system sits in a standard steel tetrahedron vibrocorer frame and can be deployed in water depths to 150m from any vessel with the appropriate A-frame assembly. The corer's frequency and amplitude can be varied for different soils. Feedback during coring can assist the engineer to alter settings for optimum performance. The increased power minimizes barrel bending and core disruption.