Ground Movements Induced by Shield Tunnelling in Non-Cohesive Soils

The causes of settlements due to tunnelling are various and interact with each other. Many attempts are made in history to model this complexity by analytical, laboratory or numerical methods. Although these techniques are still of limited use for practical purposes, they help to understand the key mechanisms of tunnelling. The objective of this book is to gain new insight on the mechanisms and to propo se new techniques to estimate and avoid settlements. The investigations are done done by means of - scale laboratory model tests, - numerical analyses, - analytical methods. Special focus is put on effects due to volumetric behaviour of soil. As a result, - it is shown that hypoplasticity with intergranular strains is one of the few constitutive models, wich is able to reproduce correctly volumetric soil behav iour for loading-unloading paths that occur in shield tunneling. - a new concept to avoid settlements is proposed. - a new analytical method to calculate the volume of the settlement trough is presented, that takes volumetric soil behaviour into account.