Geotechnical drilling

MOS soil mechanics has a wide range of equipment for geotechnical drilling operations at its disposal, the drilling is done manually or mechanically. The desired drilling depth and ground formation are determining factors for the drilling method and the equipment used.

Geotechnical drillings (manually and mechanically) are executed in accordance with NEN-EN-ISO 22475-1, the classification of the soil is executed and presented in accordance with NEN 5104. If so desired by the client, drillings are also possible in accordance with other regulations.

During geotechnical drilling operations, disturbed or undisturbed soil samples can be taken for research in our geotechnical laboratory.

Pneumatic drilling machines

Up to the level of the groundwater, the phreatic surface, drillings can be performed as (non-hollow stem) auger drilling, beneath the phreatic surface the drilling is done with a hollow stem pneumatic drill. When encountering rigid, connected layers or rubble beneath the phreatic surface, the auger is used when the pneumatic drilling is not successful.

During the drilling operation beneath the phreatic surface, water is added to ensure that the water level in the stem is either above or equal to that of the phreatic surface. Through this, the inflow of groundwater at the bottom of the drill stem and that of the soil material from the bottom is prevented. Normally, drilling mud is not used; if necessary clean water is added.

This drilling method is registered in the MOS Grondmechanica quality system. Details of the drilling procedures are adapted based on experience and the encountered soil types during the work activities.

Manual drillings

Geotechnical drillings with a short length can be performed manually. With this, auger or soil drills are screwed in manually and for every 10cm a record is made of the soil formation. Drilling manually is a particularly suitable method for obtaining a good impression of the surface layers. Depending on the soil formation the drillings can be done up to a depth of 5m below ground level. In the case of very weak soil, manual drillings are possible to greater depths.

Manual drillings are also performed as a pre-drilling at various research locations (probes, pressure monitoring wells or mechanical drillings) where cables or pipes are present in the soil. These drillings are usually done up to a depth of 1.5 m below ground level.

Core drilling

Core drillings can be performed in rock formations and/or overburden clay (clay deposit layers that overlay bauxite), in soil which is stabilized with grout or cement or in grout-cement (deep) walls.