Real opportunities for ultra high strength concrete in tunneling

From history of soft soil shield driven tunnels it is known that the required thickness of concrete tunnel linings is proportionally related to the tunnel diameter. The thickness should be approximately 1/20th of the diameter (D/20). It turns out that several structural mechanisms are dominating the required thickness at different boundary conditions. The structural mechanisms have been and still are intensively discussed.
The use of steel fibre reinforced concrete resulted in some very slender structures for bridges and roofs already. It turns out that the application of (ultra) high strength concrete is a real opportunity for tunnel linings. The application of higher strength concrete in tunnelling can result in cost savings in two ways: either by reducing the thickness of the elements or by reducing the amount of traditional reinforcement.
This paper presents the results of an extensive research to the influence of structural mechanisms on the lining thickness and discusses the opportunities of ultra high strength concrete.