Shield tunnelling is a ‘classic' method that continues to be used to this day. This more traditional drilling method can be useful in situations where, for example, it is important for environmental reasons to prevent a drop in the water table. As a pioneer in the field, Visser & Smit Hanab has more than three decades of expertise and experience with this method.
Shield tunnelling or microtunelling can also be performed under the water table, with special tools to balance earth and fluid pressures. A drill head deployed from a thrust pit closes off the pipe casing and is jacked through the ground with a rotating cutting head. The soil is mixed with water or bentonite, and pumps and slurry pipes carry the waste to a separation system or slurry chamber.
This drilling system is primarily suited to pipes with a diameter range of 600 to 3,500 mm. Interim stations can be installed to lengthen the total allowable route distance considerably. Visser & Smit Hanab has a wide variety of drill heads for a wide range of borehole diameters. With our specialised team of designers, geologists, engineers, drilling equipment operators and materials engineers, we can take on projects from conception to completion.
For more information or answers to specific questions about shield tunnelling, please feel free to contact us.