Convergence-Confinement Method for Tunnel Design

Book excerpt: This book presents the theoretical bases and the application tools for using the 'convergence-confinement' method which is a rational method largely used in design engineering for tunneling. Until recently, the stability conditions of underground works and the choice of support methods were essentially defined on the basis of good practice or empirical methods. The progress made, on one hand on the knowledge of the constitutive laws of soils and rocks and, on the other hand on the numerical modeling of the interaction between the ground and the structures have led to the development of robust design tools for tunnels supports. The convergence-confinement method makes it possible to simulate the excavation of a tunnel and the installation of the support using a simple plane strain model. The book presents the theoretical bases of the method and its most recent developments. Closed-form solutions for stress and displacement fields around tunnels are provided for elastic, viscoelastic and elasto-plastic behavior of the ground. More generally, the principles for applying the method in numerical models are presented.