Rehabilitation of Urft Dam - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 778

Figure 24.9 LFJ test 2 (vertical), stress-displacement curves, deformeter 2/4 (Wittke et al. 2012)
Figure 24.10 shows the deformation moduli determined in LFJ test 1 with horizontal
arrangement of fl at jacks. The evaluation was carried out for two cases. In case 1, no
cracks were assumed to occur in the rock around the fl at jacks (d = 0). In case 2, it
was assumed that due to tensile stresses induced at the slot's edges tensile cracks of
depth d = 0.2 m arise (Section 15.4). As a result, moduli of E = 5000 - 14,000 MPa
are obtained. The mean value depending on the assumed crack depth amounted to
MPa and MPa, respectively. The correspond-
ing results for LFJ test 2, with a vertical arrangement of fl at jacks, are represented
in Fig. 24.11 yielding larger mean deformation moduli of and
, respectively. However, due to the large scatter of the indi-
vidual values of deformation moduli between some 7000 MPa and 22,000 MPa ani-
sotropic deformability of the masonry could not be deduced with suffi cient reliability.
The dilatometer tests carried out provided deformation moduli of E = 6000 - 12,000 MPa,
yielding a mean value of (Fig. 24.12, left). A dependence on depth
could not be established. Thus, the order of magnitude of the average deformation
modulus of the masonry determined by the LFJ tests could be confi rmed by the results
of the dilatometer tests.