Deep Diaphragm Wall Activities at Randstad Rail Project in Rotterdam, The Netherlands-Article

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The RandstadRail Statenwegtracé project connects Rotterdam with The Hague and includes nearly 3 km of tunnel construction near Rotterdam Central Station. Two 2.4 km single-track tunnels were bored with a hydro-shield TBM; the remaining section was built cut-and-cover. The article focuses on three deep excavation pits: the launch shaft, Blijdorp underground station and the arrival shaft.<br /><br />Ground conditions posed major challenges: soft clay and peat overlie dense sand, with a pressurised groundwater layer below. Diaphragm walls up to 42 m deep and 1.2–1.5 m thick were embedded in an impermeable layer to seal the excavations. At Blijdorp, the 22 m-deep pit required exceptionally heavy reinforcement, including cages weighing up to 50 tonnes, and recoverable steel joint elements with waterproof seals.<br /><br />TBM entry and exit required openings through the diaphragm walls without allowing soil or groundwater into the pits. Underwater concrete sealing blocks provided temporary support and control during these operations. Because the TBM’s cutting tools cannot pass through steel reinforcement, selected wall sections were built with glass-fibre-reinforced polymer (GFRP) bars. These “soft eyes” could be cut by the TBM, replacing the client’s proposed lime-cement transition zones and offering a faster, less costly solution.<br /><br />The diaphragm-wall works were completed despite the difficult ground and unusual scale. The project also used extensive ground improvement, including lime-cement columns, grouting and jet grouting, while ground freezing was planned for tunnel cross-passages.

Keywords

RandstadRail

Statenwegtracé

Rotterdam

The Hague

tunnel construction

diaphragm walls

TBM

Blijdorp station

GFRP bars

ground improvement