Finite Element Method (FEM) - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 279

in width and 800 m in length. For a stress-strain analysis a computation section in
the order of magnitude of the 30 m wide and 60 m long section illustrated in Fig.
10.54 (below) would be sufficient.
10.6.2 Representation of Results
The distribution of piezometric heads is normally represented by means of equipoten-
tials as already shown in Section 7.1 using the example of a gravity dam. In this example
only the foundation rock was assumed to be permeable (Fig. 7.1). As another exam-
ple, Fig. 10.55 shows the calculated equipotentials in both the foundation rock and the
gravity dam in the longitudinal section through the middle of the valley as a result of
a three-dimensional stability analysis. Below the upstream side of the dam a vertical
grout curtain is carried out so that the reduction of hydraulic heads to a large extent
takes place in the dam and the grout curtain both exhibiting a reduced permeability
compared with that of the foundation rock.
Figure 10.55 Equipotentials in a gravity dam and the foundation rock, longitudinal section
10.6.3 Example
On behalf of the German Railways an extension of the urban railway of Stuttgart from
the airport station underneath the airport to Filderstadt-Bernhausen was constructed.
Thereby, the complete airport including the runway of the airport was undercrossed
with a 2.1 km long mined tunnel (Section 20.3).
The runway, which is very sensitive to subsidence, is located in part above the so-called
“Filder loam” and in part above valley deposits of soft clay, both soils exhibiting a low
permeability. A sedimentary rock consisting of an alternating sequence of horizontally
bedded limestone and sandstone, as well as claystone follows below the soil. Below the
alternating sequence a claystone with limestone layers is located. The location of two
of them, the so-called “Oolithenbank” and “Psilonotenbank”, is specified in Fig. 10.56.