Rock Core Drilling

Service 05

Where a probe or a wash bore can only tell you that refusal was met, coring tells you what was met. A diamond-impregnated bit cuts an annulus around a cylinder of ground, and that cylinder is recovered in sequence — an unbroken physical record of the material from the surface down to the depth drilled.

What the core tells you

The recovered run is measured and logged as it comes out of the barrel: total core recovery (TCR), solid core recovery (SCR) and rock quality designation (RQD), together with the rock type, degree of weathering, joint spacing and the condition of the fracture surfaces. Those figures describe the rock mass as a whole rather than a single point, which is what founding level and excavation decisions actually turn on.

How the work is carried out

Coring is usually run as a continuation of a soil investigation borehole — wash boring or casing through the soil profile, then coring once rock is reached. Core is recovered in runs, placed in boxes in sequence, marked with depth and run boundaries, and photographed before it leaves site. Samples can be selected from the core for laboratory strength and index testing where the scope requires it.

Where it is used

Establishing founding levels for piled and raft foundations; confirming the depth and quality of rock beneath cut slopes and excavations; assessing rock as construction material or for quarry development; investigating cavities and karst conditions in limestone; and recovering intact core for mineral occurrence studies.

What you receive

Core logs with depth, description, recovery and RQD, core box photographs, laboratory test results where testing is included, and interpretation of the rock profile in the investigation report.