Ziegenbergtunnel, B 54/62- Hüttentalstraße

Geologically, the ground at the Ziegenberg Tunnel can be described as follows: Beneath a loose ground layer of from roughly 2.0 to- 8.0 m comprising silt and stone layers (slope debris), solid rock is to be found consisting of folded, slaty layered rocks of the Lower Devonian Siegener Schichten. The solid rock is by and large interbedded clay shales and grey wacke and sandstone layers. In the east, in the form of gallery sections (open at one side), 22.0 m of the north tube and 52.0 m of the south one were created in a slope zone by cut-and-cover. In their final state, these gallery sections are filled at one side. The transition area to the cut steep slope was provided for with an element wall, a so-called lattice wall, on which plants are placed ln the west, linking up with structure BW 29.1, in each case, 3 tunnel blocks were produced in an excavation. In their final state, they are completely covered over. The fill ends in a noise protection wall at plots of land on the Ehlerstrasse. 280.0 m of the north tube and 240.0 m of the south one had to be completed by mining means. The maximum overburden of the tubes amounts to approx. 26.0 and the minimum at about 8.0 m. The axes of the 2 tunnel tubes run at a sharp angle to the contour line of the slope which has to be passed through. The ground thrust which has to be overcome ranges up to a height of 23.0 m. Apart from the temporary pre-cut, permanent securing of the slope had to be undertaken here. The Ziegenberg Tunnel drive was executed with shotcrete. Originally; drill+blast was to be applied but after a few metres, cutting had to be adopted as blasting caused damage to the buildings in the Hubertusweg. In order to minimise settlements in the western portal zone, advance securing and the setting up of a longitudinal beam in the roof section were scheduled. In addition, the subsurface was additionally improved by means of ground injections undertaken from the surface. The inner shell of reinforced concrete B 25/B 35 has wall thicknesses varying between 30 and 40 cm. ln order to seal off and divert any underground water that might be present, a plastic waterproofing membrane is laid between the shotcrete and the inner shell. Water is transferred into drains, which can be laid at both sides of the tunnel tube.

Country: Germany
Region: Nordrhein-Westfalen
Tunnel utilization: Traffic
Type of utilization: Road tunnel
Client: Bundesrepublik Deutschland, Westfälisches Straßenbauamt Siegen
Contractor: Hochtief AG
Main construction method: Trenchless
Type of excavation: Drill-and-blast/Cutterdrive
Lining: In-situ concrete
No. of tubes: 2
Tunnel total length: 356 m
Diameter: 11.0 m
Cross-section: 82-94 m²
Contract Volume: approx. 60 mill. DM
Construction start/end: 1994 till 1998
Opening: end of 1998