Tunnel with Vision

by Hans-Joachim Sager, Dir.; Philip Holzmann AG, D�sseldorf, Germany,
Martin Herrenknecht, C.E.O.; Herrenknecht AG, Schwanau, Germany,


Serial Information: Civil Engineering—ASCE, 2001, Vol. 71, Issue 2, Pg. A2-A9


Document Type: Feature article

Abstract:

Two tunnel boring machines that are being used to bore a pair of 6.6 km long tunnels under the Westerschelde estuary in the southern Netherlands must dig through loose sand and sticky clay and under water pressures up to 6.5 bars. A soft ground probing system mounted on the cutter head will use high-frequency waves to detect changes in the soil ahead of the machine. Data recorded by accelerometers will produce a three-dimensional image of conditions ahead that will help the machine operator adjust the drilling process to avoid obstacles or voids. Other technologies used by the machines to handle the varying geological conditions are a rotary crusher and agitators to keep clay from clogging the cutter head and fast-setting mortar to seal water out of the tunnel as it expands.

Subject Headings: Tunnels | Equipment and machinery | Water pressure | Soil water | Soil pressure | Soft soils | Clays

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