ABSTRACT
The internal forces of the pipes are almost zero after the installation, comparable to other passive support measures like rock bolts. The stress transfer, due to the previous excavation steps, has an influence on the ground and on the already installed support.The newly installed pipes are not affected by previous activities, whereas every following construction process that causes a stress transfer starts to activate the supporting effect of the pipes. The spatial displacement characteristic developing during excavation controls the activation of the supporting effect after the installation of the pipe umbrella.
