Contribution to the Design of Tunnels with Pipe Roof Support

The working area of tunnels is often supported with a pipe roof support system in weak ground. The experience gained from former projects led to the conclusion that this support system decreases the subsidence during tunneling. The lack of knowledge about the geotechnical system behavior of this support system disables the designer from determining the basic design parameters depending on analytical and/or empirical solutions. This
fact often leads to conservative and uneconomical designs. In order to overcome this lack an extensive monitoring program was executed on site. Using these data sets and the results of laboratory investigations the geotechnical model for this support system was determined in numerical simulations. Starting with this back calculated model the variation of basic design parameters was investigated. In this publication the focus will be set on the influence of the dimension and number of pipes on the displacement magnitudes at the tunnel level