Sampling is an essential part of investigating the ground conditions. Retrieved soil samples provide direct information about what the soil consists of, and we can further investigate strength and deformation properties.
Since its establishment in 1953, NGI has focused on developing equipment and methods that can investigate and describe ground conditions in the best possible way. An example is the development of thin-walled piston samplers (see the illustration in the picture at the top) for taking undisturbed samples in soft clay.
Typical sampling for geotechnical purposes is stamp and block sampling. Piston samplers are pressed down into the bottom of boreholes, and by applying a vacuum to the top of the sample cylinder, the soil sample inside the cylinder will, after being pressed down, follow when the cylinder is pulled up.
Sampling in the field - block dust (middle) and soil samples from Sonic drilling
Geotechnicians want the soil samples to be disturbed as little as possible regarding the sampling. That is why you want as large dimensions as possible. Block sampling results from this, where the soil samples have a diameter of 25 cm.
We also carry out environmental technical sampling with core drilling (Auger drilling) and excavation.