Borehole
A borehole is a drilled hole that samples and logs soil at depth for the geotech, reaching deeper than a test pit. It feeds the bore log and AS 2870 site class.
Ask Chalkline about this →A borehole is a drilled hole made during site investigation to recover and log the soil and rock layers at depth before footings are designed. A drilling rig or auger bores down, samples are taken at intervals, and the findings are recorded as a bore log.
Borehole vs test pit: a borehole reaches deeper than a test pit and lets the geotechnical engineer sample soils a pit cannot reach. Test pits are quick and cheap for near-surface soils on a standard block; boreholes suit deeper investigation, multi-storey buildings, piled footings, or sites where the founding layer sits well below the surface.
What it feeds:
- Samples drive shrink-swell and soil-strength testing.
- The bore log and results go into the soil report and the site classification under AS 2870.
- For piers and deep footings, the borehole confirms the depth to the bearing strata.
Common limitation: like a test pit, a borehole only samples one point. The number and spread of boreholes across a site determines how well the investigation captures variation in the ground.
Also known as: bore, drill hole.
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Last updated: 2026-05-24. Verified: 2026-05-24. Quarterly review for currency.