Wechselwirkungen zwischen tiefliegendem Tunnelvortrieb und bestehendem Tunnel im Bereich von Störzonen – Modellierung versus Realität

Abstract

The influence of a tunnel drive on an existing tunnel is primarily the result of the tunnel geometries, the relative location of the two tunnels, the geological‐geomechanical conditions and the associated primary stress state. During construction of the Brenner Base Tunnel, there are constructionally relevant interactions in some places between the running tunnels and the exploratory tunnel (EKS) running centrally and 12 m deeper. The rock mass stress as a result of driving the running tunnels here leads to deformations of the previously driven exploratory tunnel. Due to the high loading on the outer linings of deep tunnels and the high stiffness of the already hardened shotcrete support, slight deformation can cause local cracking in the support layer. This article compares the observed deformations in a fault zone intersecting at a flat angle with numerical simulations, which enables investigation of the geomechanical problems. Comparison of the calculation results with the real deformation behaviour permits the validation of the numerical simulations and the reliability and limits of such analyses.

15 km TBM exploratory tunnel excavation in the construction Lot H33 of the Brenner Base Tunnel

“…In some sections, the supported invert had to be com pletely broken out and newly concreted, with the invert being anchored down with IBO anchors. In particular, under these difficult rock mass conditions, interference occurred between the three tunnels [3].…”

“…It was already clear after the first few kilometres of tunnel that the rock mass conditions were very difficult, especially in the first section from km 0 to 1.5 [2]. This section was character ised by flat dipping foliation in combination with frac tured and sometimes squeezing rock mass, which led to ravelling and collapses behind the finger shield and to de formations in the crown and invert [3]. In this area, the assembly cavern for the two shield machines of the follow ing contract was originally intended.…”