In-situ Testing
GGPGeo provides a range of services for testing the physical properties of soil. The results of these tests have various applications, such as the determination of the type of foundations required for a building of structure.
Mackintosh Probe
The Mackintosh Probe is a lightweight handheld device which can be conveniently used for the investigation of soft soil up to a depth of 10m. It can be carried and used in difficult terrain with poor access such as swampy ground.
The results of Mackintosh Probing can be shown to be both repeatable and indicative of soil strength.
Correlations can be established between 'M' and 'N' and also undrained shear strength for soft clays. This allows effective targeting of any subsequent boreholes or tests that may be required and also the interpolation of soil properties between boreholes.
Dynamic Probe (DPSH)
Dynamic probing involves driving a cylindrical fixed cone into the ground using a high frequency percussive hammer with a weight of 63.5kg dropped 750mm.
The cone is attached to a 1m section steel rod with a nominal diameter of approximately 35mm and graduation markings set at 100mm intervals.
GGPGeo uses our tracked heavy duty Dart Competitor rig for this application.
Blows per 100mm are recorded.
Further rods are then added and the process is continued until the probe refuses to penetrate the ground or the test reaches the required depth.
The results from this method can be correlated directly to a standard penetration test 'N' value. The results are plotted on a graph, providing a visual interpretation of the different soil strata encountered.
Shear vane
The shear vane test is an effective field method of measuring the undrained shear strength of a cohesive soil. The test is carried out with the handheld field shear vane. This consists of a rod with vanes mounted to it that is inserted into the ground and rotated. A gauge on the top of the rod measures the torque required to cause failure of the soil and provides a conversion to shear strength.
CBR (California Bearing Ratio)
The California Bearing Radio (CBR) is a measure of the strength of the subgrade of a road or other paved area, and of the materials used in its construction.
The ratio is measured using a standardised penetration test first developed by the California Division of Highways for highway engineering. Empirical tests measure the strength of the material composed to a known standard material (crushed California Limestone).
Traditionally CBR values were obtained either in the laboratory, or in-situ using an arrangement involving a small rig attached to the rear of a pick-up. We are able to provide this service using the Zorn Lightweight Deflectometer. This is a lightweight portable tool that uses a drop weight to measure elastic deflection of the soil or subgrade to obtain CBR values, which are recorded digitally allowing quick decisions to be made on site.
