Swelling Rock - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 198

Figure 8.14 Shear strength of discontinuities
Figure 8.15 2011 horizontal rock mass permeability of unleached Gypsum Keuper, results of Lugeon
tests in vertical boreholes
At the universities of Karlsruhe and Darmstadt in Germany, a large number of
long-term laboratory swelling tests were conducted on intact rock specimens un-
der different vertical loads that differed during the tests. Figure 8.16, for example,
shows the measured vertical swelling strains and corresponding stresses for an in-
dividual test with several load levels. Since not all tests were conducted up to a
steady state of swelling (i.e. full saturation was reached), some of the test results
were extrapolated (Wahlen 2009). These swelling tests yielded a considerable scatter
of results, which may be due to both the different mineralogical composition of
the relatively small specimens and uncertainties of extrapolation. However, it was
shown by Wahlen (2009) that the results of these tests can be well interpreted by
the swelling law illustrated in Fig. 8.5. This result is contradictory to the opinion of