AJRM as basis for design and construction of more than 70 km of tunnels of the Railway Project Stuttgart‐Ulm

The tunnels of the railway project Stuttgart‐Ulm are located in sedimentary rock of the Keuper Formation, the Black Jurassic, the Brown Jurassic and the White Jurassic formation. The two longest tunnels are excavated by tunnel boring machine over most of their length. The remaining tunnels, which the authors are involved in, are excavated by conventional tunnelling. All tunnels are designed on the basis of the AJRM‐method. This method is based on an anisotropic, elasto‐viscoplastic model for jointed rock and corresponding FE‐software, which has been extended to seepage and swelling. The method has been applied to practical projects for the last 40 years. By means of rock mechanical test programs and back‐analyses of projects in a variety of rocks, the reliability of the predictions is quite high and the application leads to safe and economic solutions. Special emphasis is given to tunnels located in swelling gypsum Keuper. The phenomena of swelling and leaching are described and a swelling model is outlined. The evaluation of the rock mechanical parameters and a method of analyses are explained. On this basis, the design principles and package of measures applied for the tunnels located in anhydrite‐bearing rock are described. Some important aspects with regards to tunnelling in leached Gypsum Keuper and in the other Keuper layers as well as the Black Jurassic are addressed. For the 8.8 km long Boßler Tunnel, located in the Brown and White Jurassic, for an approx. 900 m long section in the Aalenium 2 with a maximum overburden of 280 m squeezing rock conditions had to be anticipated. By means of a vertical exploration shaft and a connecting exploration gallery, an improvement of the predicted characteristic rock mechanical parameters could be justified, thus enabling TBM‐tunnelling also in this section, with an increase of the segment thickness from 45 to 65 cm. For the Steinbühltunnel located in White Jurassic, special emphasis was placed on karstic rocks. The corresponding measures are described.