Motorway A71 / Schmücke Tunnel

In the course of the new construction of the federal motorway A71 in the area between the AD Oberröblingen (BAB A38) and the AS Sömmerda (B176) approx. 40 km highway of the BAB A71, 33 highway bridges, ten overpass constructions as well as the 1,7 km long, 2 tube Schmücke tunnel were built. As a geotechnical challenge, the route crosses a zone of the Gypsum Keuper with sinkholes, the „Helmeaue“ with mighty soft layers and two former mining areas (deep lignite mining). In the course of the production of the Schmücke tunnel, almost the complete triad from the „lower Keuper“ to the „lower sandstone“ had to be crossed. This rock formation is characterized by numerous disturbances (northwestern foothills of the „fin-disturbance“ as well as strongly changing rock strengths and groundwater conditions.

location 
BAB A71 – AS Heldrungen to B85
client 
DEGES Deutsche Einheit Fernstraßenplanungs- und -bau GmbH für den Freistaat Thüringen
project period 
2002 - 2011
scope of services 
  • tendering and supervision of field work with drilling depths up to 100 m and extensive investigations in the borehole (BAV,ETIPS,ABF,WD-experiments)
  • supervision and interpretation of geophysical investigations (tunnels and sinkhole areas)
  • subsoil exploration and foundation consultation for track and structures
  • engineering geological expertise for the tunnel
  • geotechnical consulting in the pre- and submission phase
  • supervision and evaluation of long-term pumping tests
  • hydrogeological report for the area of influence of the tunnel
  • vibration and noise measurement in explosive tests to determine the impact of bat winter quarters by blasting in tunneling
  • survey on the stability of the pre-cuts and portals of the tunnel
  • examination of the stability calculation for the permanent slope backup at the north portal
  • geotechnical consulting and supervision during construction pre-cuts and slope backup
  • opinion on the reuse of heavily gypsum soils
  • supplementary detailed investigations in the active sinkhole area with
    • aerial photography
    • geophysical measurements
    • preparation of possible security variants
    • draft for the preferred variant and preparation of the associated tender documents
  • additional detailed investigations in the field of old mining areas with
    • shaft localization
    • collaboration in mountain damage hazard analysis
    • risk assessment for the traffic systems
  • planning including preparation of the tendering documents as well as site management for the measures in the old mining areas