Euradwaste '08 - EU Bookshop - Europa

porosity (%)
10
8
6
4
2
208/38
σ 1,3 = 10 MPa
w = 0.64%
208/39
σ 1,3 = 20 MPa
w = 0.46%
0
0 100 200
time (d)
300 400
473
208/36
σ 1;3 = 3 MPa
w = 0.42%
Figure 1. Comparison between measured and calculated long-term creep behaviour for the ZHANG
model, calculations performed with best fit for wetted salt brick samples. Porosity vs. time (symbols
indicate the measured behaviour, continuous lines the calculated one, colours mark the stress conditions
for the creep-test).
a) b)
Figure 2. Hydraulical properties of salt bricks. a) Porosity-permeability data for dry salt brick material
deformed in compression under triaxial loading conditions at room temperature. b) Relationship
between gas threshold pressure and intrinsic permeability for various low permeability rock
formations (e.g. claystones, shales, sandstone) – modified after [4].
Shear tests were performed to investigate contact properties between saltbrick surfaces and the rock
salt. Whereas at dry conditions only some friction occurs, significant strengthening is observed
when moisture is present because of activation of cohesion (Fig. 3). This observation offers a direct