Civil Engineering Reference
In-Depth Information
25
Stabilization of a Rock Mass Slide
25.1
Original Design
During construction of a new section of the German federal freeway (Autobahn) BAB
A46 from Arnsberg/Uentrop to Meschede/Wennemen the excavation of an approximate-
ly 50 m deep cut was carried out (Fig. 25.1). According to the geotechnical expertise that
the tender design was based on, the rock mass in the area of the cut consists of a steeply
dipping alternating sequence of Devonian sandstones and clay slates with single interca-
lated banks of sandstone and clay slate. The bedding dips at 45° to 70° in southerly direc-
tion. In this expertise no reference was made with regard to fault zones or other tectonic
features. As commonly happens, it was based on the results of only a few core drillings.
Figure 25.1
Rock slide on a 50 m deep cut on freeway BAB 46 near Meschede (Germany),
aerial view (Oehler 2012)
According to this assessment, the slopes of the cut were designed with an inclination of
1:1. Only a few temporary anchors for local near-surface support of the slopes were in-
stalled. The sequence of excavation and the corresponding times are shown in Fig. 25.2.
During excavation of a 100 m wide strip at the southern slope in summer 2001 dis-
placements up to 30 cm were observed, indicating the initiation of a rock slide. As an
Search WWH ::
Custom Search