Westerscheldetunnel

Proof of ultimate limit state and serviceability limit state for tunnel boring machines
Expert consultation in the course of the occured event of deformation damage

With the Westerschelde tunnel, the Dutch province Zeeuwsch-Vlanderen was linked to the remaining land parts via a capable street connection. The tunnel lies underneath the shipping gully ”Pas van Terneuzen”, which is the essential harbour entry to the harbour of Antwerpen, being burdened with a high amount of ships.

The tunnel was constructed with two offset-parallel TBM drivings, with an inner diameter of approx. 11.3 m and a length of 6,600 m each. The driving was processed with fluid-supported working face against water pressures up to 6.5 bar.

The escape routes, which are arranged at intervals of 250 m, between the track tunnels were driven against by utilising cross-cuts, in order to protect the constructing ground glaciation from the tubbing tubes.

In the framework of structural stability and usability verifications for tunnel boring machines, ZPP or the predecessor company rendered the following services:
_Definition of load assumption and objective evidence criterion
_Modelling of interaction between soil and TBM
_Evaluation of factors of influence for the load bearing capacity and deformation behaviour
_Stress analysis
_Proof of serviceability limit state
_Verify of structural stability and buckling behaviour
_Sensitivity analysis for unsure input parameters and basic condition
_Expert consultation in the course of the occured event of deformation damage at both TBMs


Over the course of the driving, deformations on the shield tail occurred, being verified during the technical consulting through numeric calculations by ZPP or the predecessor company. The further deformation behaviour was subsequently estimated.

The Dutch Ministry for Transport, Water Economy and Public Operations was the main client for the project, which entailed total construction costs of approx. 730 million Euros.