Möglichkeiten der Prognose von Oberflächensetzungen beim Tunnelvortrieb im Lockergestein - Teil 1: Empirisches Prognoseverfahren

Possibilities to predict the surface settlement during tunnelling in soil - Part 1: empirical erediction method.

Tunneling in soft ground always leads to stress rearrangements and deformations in the surrounding soil. Therefore, while planning shallow tunnels in areas sensitive to settlements, the prediction of the extent of ground subsidence is of prime importance. The deformations can be detected by the evaluation of measurement data available from previous tunnel project sites - the empirical prediction - or by numerical calculations. In part 1 of the following publication, the empirical prediction method of Fillibeck is introduced. For deriving this empirical method, more than 400 measuring sections from actual shotcrete and shield tunnel projects were analyzed. Among others, the influence of the excavation method, geological situation, tunnel depth and tunnel diameter on the settlement trough was described. Because of the large number of comparable measurements, it was possible to describe the size of the settlement trough in relation to the occurrence probability. The second part of the publication deals with numerical Finite Element Methods. For the calculation of settlement troughs, the suitability of different material models is analyzed and different calculation methods are described, distinguishing between 2D, 3D and 4D calculations. Finally, in comparison to the empirical method, the application spectrum and the limitations of numerical methods are discussed.