Cover sleeve for underground tunnel

摘要

The underground tunnel (1) has a sleeve (2) of rigid material. The sleeve outer side is covered with a layer of compressible material. The compressibility of the layer is anisotropic and can be greater parallel to the axis of the tunnel than radially. The covering layer is of a material which is form-stable under the pressure of the ground in a radial direction. The covering layer can be movable relative to the outer surface of the tunnel. The compressibility of the outer layer can be orthotropic.