PSI - Issue 10

D. Kotsanis et al. / Procedia Structural Integrity 10 (2018) 112–119 D. Kotsanis et al. / Structural Integrity Procedia 00 (2018) 000 – 000

118

Table 2 (continued). H-B peak strength parameters along with the range of confining pressures. Rock type Rock code

Range of confining pressures (MPa)

Peak strength parameters C 0 (MPa) m i

Micritic Limestone Micritic Limestone Compact Limestone Porous Limestone Porous Limestone Compact Limestone Compact Limestone Compact Limestone

S2 RAF S3-2 S2 THOR S5-2 S3 MARK S1-3 S3 MARK S2-6 S4 MARK S1-2 S4 PAIAN S6-8 S4 THOR S3-4 S8 THOR S1-1 S4 SPAT S3-2 S8 RAF S2-2 S15 PAL S1-2 S2 SPAT S1-2 S9 PAL S2-2

2.9-15.1 2.1-13.2 2.3-14.2 0.6-5.5 0.6-5.3 3.0-22.1 2.4-25.1 2.0-18.1 1.1-9.3 3.0-11.0 0.6-15.0 2.5-10.0 3.2-10.0

49.8 46.6 51.3 13.4 19.7 92.8 95.5 59.8 34.8 23.5 62.4 41.7 52.6

4.8

10.8

5.7 2.3

11.4

5.3 8.8 5.4 7.8 9.1 7.6 6.5

Sandstone Sandstone Sandstone

11.2

Breccia Breccia

In most of the cases the failure envelopes deviate more or less from the linear model, that the M-C criterion describes, so the application of the H-B criterion fits better to the peak strength data increase with increasing confining pressure. This is shown in Fig.4, for the same specimens as in Fig.2, along with their H-B fit curves (dashed curves).

100 120 140 160 180 200

σ 1 = σ 3 +130.3(5.7 σ 3 /130.3+1) 0.5

σ 1 = σ 3 +93.5(8.7 σ 3 /93.5+1) 0.5

σ 1 = σ 3 +62.4(9.1 σ 3 /62.4+1) 0.5

S15 PAL S1-2 S22 LAV S1-2 S1 SPAT S2-4 S3 MARK S1-3 S6 THOR S5-1

σ 1 (MPa)

σ 1 = σ 3 +51.3(5.7 σ 3 /51.3+1) 0.5

0 20 40 60 80

σ 1 = σ 3 +16.5(9.7 σ 3 /16.5+1) 0.5

σ 1 = σ 3 + C o ( m i σ 3 / C o +1) 0.5

0

5

10

15

20

25

σ 3 (MPa)

Fig. 4. Peak strength data along with their H-B fit curves.

The m i values for marbles and brecciated marbles range between 5.1 and 11.5, for clastic sedimentary rocks between 6.5 and 11.2 and for limestones between 2.3 and 11.4, respectively. The values for the metamorphosed calcite rocks are in good agreement with those proposed by Marinos and Hoek (2000). However, for some sedimentary rocks, such as clastic formations, sparitic limestones and micritic limestones, the m i values determined in this work fall below the range given by Marinos and Hoek (2000).