Visser & Smit Hanab has been using classic drilling technologies such as rocket drilling and open front drilling since the late 1970s. Nowadays, we also have years of experience with shield drilling methods such as the earth pressure balance shield method, the mix shield method and the mechanical pressure balance shield method. Above all, we have all the necessary equipment in various diameters in-house.
Although horizontal directional drilling is being used more and more when laying new cable and pipeline networks, traditional methods such as shield tunnelling still remain popular. Shield tunnelling can be carried out in all types of terrain. At the end of the 1970s, when shield tunnelling became an increasingly popular technique, Visser & Smit was one of its pioneers. We now have significant expertise and extensive experience in this field.
The shield tunnelling method, or closed front drilling, is based on earth pressure and fluid balance. This method is suitable when the groundwater may not be lowered, e.g. for environmental reasons. When this method is used, the front of the casing pipe is closed by a drill, i.e. the drilling shield. The drilling shield leaves a pressurised cylinder and the rotating cutter wheel excavates the soil. The soil is mixed with water or bentonite. Pumps and transport lines remove waste to a separator or a slurry depot.
Shield tunnelling can be carried out below groundwater levels. This drilling system is suitable for pipes with a diameter of 600-3,500 mm and we have drilling shields of various diameters available to carry out this work. Installing intermediate stations means the length of the bores can be increased.
Having our own designers, geologists, engineers, drilling experts and equipment specialists in-house is a key added value because this means that we can provide a holistic, turnkey delivery of our projects. Moreover, we do not shy away from challenges. ‘Impossible' is not part of our vocabulary
Drilling with absolute precision using the auger drilling technique is limited by the diameter of the pipe used (10-100 cm) and the length of the bore (a maximum of 100 m). Guided auger drilling is possible with the aid of pilot pipes with an optical connection, guiding head, theodolite with built-in camera and a monitor. The process can be performed both above and below the groundwater level. We have an extensive range of machines, modern equipment and a full range of drilling materials available to conduct auger drilling projects.
For the WRK project in the Netherlands, Visser & Smit Hanab constructed a double water pipeline. over 5 km using a trenchless technique. The boreholes were drilled using the closed front shield drilling method using a Herrenknecht AVN 100 drilling machine at a depth of 10 m below the surface through the Pleistocene sand layer. 24 drillings with a total drilled length of 10 km (for the 5 km double pipeline) were used to construct the pipeline. The steel pipes were 1,200 mm in diameter.
This video shows how the project was carried out.