Examples of Testing and Monitoring Programs - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 610

Figure 19.3 Structural model and rock mechanical parameters of Lias α and Knollenmergel

The parameters used in the stability analyses were selected conservatively as the lower
bounds of the characteristic moduli and shear parameters specified in Fig. 19.3 (Wittke
& Grüter 1982, Wittke 1990, Wittke 1991, Wittke & Züchner 2008).

19.3 Urban Railway Stuttgart, Construction Lot 11,

Exploration Shaft and Adit

In the planning phase for the construction of the Station Schwabstraße of the urban
railway in Stuttgart (construction lot 11), a testing and monitoring program was carried
out in an exploration shaft and adit. These were constructed before the main construc-
tion was started.

During sinking of the ca. 30 m deep shaft with a diameter of 2.2 m (Fig. 19.4) the
walls were mapped. The encountered so-called leached Gypsum Keuper, being a
residual rock, has been transformed from undisturbed unleached Gypsum Keuper
(Section 8.1), by dissolution of sulfate. The sulfate was removed with the groundwa-
ter while the clay and silt fraction of the rock were decomposed due to leaching but
remained in place. The leached Gypsum Keuper consists of an alternating sequence
of residual silts, weak siltstone and sound siltstone layers. The siltstones that are not
yet completely decomposed are intersected by steeply dipping joints with a spacing
of some 10 cm or less. The joints mostly end on horizontal and sub-horizontal bed-
ding-parallel discontinuities.