GEOTECHNICAL

Borehole Log (Bore Log)

Depth-wise record of strata, SPT N-values, samples + water table in a borehole

Also calledbore logborehole logdrilling logsoil profile logstrata chart
Related on InfraLens
CODES
Definition

A borehole (bore) log is the formal depth-wise record produced as a borehole is drilled — it tabulates each stratum's description and thickness, the depth and type of every sample, SPT N-values at each test depth, ground-water level (on striking and after stabilisation), and any drilling observations (cavities, loss of water, refusal). IS 1892 standardises its content and presentation.

The set of bore logs across the site is the primary raw output of the investigation; the geotechnical engineer interprets them — with the lab results — into design parameters and the recommended foundation. Accurate, contemporaneous logging matters: mislabelled depths or missed water tables propagate into wrong bearing capacity, pile lengths and dewatering, and the logs are key evidence in any later foundation dispute.

Where used
  • Primary record of every geotechnical borehole
  • Deriving SBC / pile capacity + foundation depth
  • Cross-section + stratigraphy preparation
  • Tender geotechnical baseline + risk allocation
  • Forensic + dispute documentation
Acceptance / threshold
Logged per IS 1892 content + format; strata, sample depths, SPT N-values and water levels recorded contemporaneously by a qualified person. The interpreted parameters in the report must be traceable to the logs.
Frequently asked
What information does a bore log contain?
Stratum descriptions + thicknesses, sample depths/types, SPT N-values, ground-water levels (initial + stabilised) and drilling remarks, presented per IS 1892.
Why must water table be recorded in a bore log?
Ground-water level governs effective stress, buoyancy, bearing-capacity reduction and dewatering design. A missed or wrong water table leads to under-designed foundations and flooded excavations.
Related terms