TECCO slope stabilization system - Geobrugg AG

Slope stabilization / Photo documentation / March 2010
TECCO ®
slope stabilization
Weisenbach-Langenbrand / Germany
2
Object: Slope 2.10, Weisenbach-Langenbrand in the
Murgtal region, alongside the B 462 road
Building promoter: Federal Republic of Germany, represented by the
Karlsruhe Regional Council, Construction Offi ce
Mitte (Central), Germany
Geotechnical investigations,
planning, construction
supervision: Ingenieurgruppe Geotechnik GbR, Kirchzarten,
Germany
Contractor: Sachtleben Mining Services GmbH, Wolfach,
Germany
Implementation: October/November 2009
Slope stabilization: TECCO ® -mesh covering in combination with nails
Max. slope height: H = approx. 15 m
Subsoil: Granite
Area: 2‘000 m2 Slope gradient: α = 80 degrees
Mesh: TECCO ® -system G65/3 mm
Erosion control mat: TECMAT
Spike plates: TECCO ® -system G65/3 mm
Nails: GEWI D = 32 mm
Nail length: L = 6 m / 3 m
Nail grid: a = b = 3 m
As part of the general geotechnical mapping of rock slopes along the B 462 in the
Rastatt district, the slope at Weisenbach-Langenbrand was evaluated as being a
high-risk area for rockfalls and avalanches. The rock is made of a fi ssured granite
known as Forbach granite. The side-cut for the road formed a slope up to 15 m
high and with an average inclination of around 80°. Protection was provided in the
form of a light protruding rockfall protection net. The rockfall catchment area in
relation to the road is less than 2 m. There was nothing to limit the rockfall catchment
area. Fissures in the fault structure undercut the slope at an angle of around
30°. Bodies of rock can thus come away from the slope and slide down the fault.
In March 2007, a rockfall occurred in which a body of rock came loose from the
upper section of the slope, broke through the fl imsy net and landed on the road.
The TECCO ® slope stabilization system was recommended as a protective measure.
The rock nails (GEWI 32 mm) are 6 m long in the fi eld and 3 m long at the edges. A
nail grid of 3 x 3 m was proposed, with the nails being inserted in slope troughs
where possible. This can lead to variations in the grid. In addition to the boundary
ropes, vertical and horizontal lateral ropes were envisaged, which were also designed
for insertion into slope troughs in order to obtain the maximum possible mesh
tension. A one-meter-high rockfall interception apron was installed at the head of
the slope. An erosion control mat was laid over the sediment layer at the top end
of the slope. The old net had previously been removed and the slope cleared.