26/09/2026
The Mackintosh Probe Test is a lightweight dynamic pe*******on test used in geotechnical engineering to assess soil consistency, estimate soil strength, and determine the bearing capacity of soft soils.
Equipment UsedCone: A hardened steel cone (typically a 30° or 60° cone tip) attached to the bottom.Rods: Steel rods (usually 12 mm to 16 mm in diameter and 120 cm long) connected by couplings.
Hammer: A 5 kg drop hammer that falls freely through a fixed height of 30 cm (300 mm) along a guide rod.
Test ProcedureSetup: Place the cone-tipped rod vertically and perpendicular to the ground at the test location.Marking: Mark the steel rod at regular 30 cm (0.3 m) intervals.Driving: Lift the 5 kg hammer to the top of the guide rod and release it to drop freely, driving the cone into the soil.Recording: Count and record the number of blows required for the rod to pe*****te each 30 cm depth increment.
Completion: Continue the test until reaching a maximum depth of 15 meters, or until the blow count exceeds a high resistance threshold (such as 400 blows per 30 cm).Purpose and ApplicationsSoil Profiling: Helps identify subsurface soil layers, variations, and the thickness of soft or unsuitable deposits (like peat or soft clay).
Bearing Capacity: Blow counts correlate empirically with soil strength parameters, unconfined compressive strength, and allowable bearing capacity.
