Quantifying the Size Effect of Rock Mass Strength

Rock mass assessment — what goes wrong?

“…The author notes that in Figure 1(b) the scale for applicability of rock mass strengths is of the order of 6 to 10 blocks and increasing to 12 to 20 blocks in Figure 1(c). The latter is in keeping with the results of modelling presented by Cundall et al (2008), whereby once the scale exceeds 10 to 15 block dimensions, the rock mass strength asymptotes and reaches the representative elementary volume (REV), a concept presented by Cunha (1990) as cited in Cundall et al (2008). This is somewhat intuitive as most practitioners accept that when dealing with slopes, the scale of the problem well exceeds the block size, and hence once the slope scale exceeds the REV, the circles shown in Figures 1(b) to 1(e), the HB criterion is applicable.…”

Estimating geometrical and mechanical REV based on synthetic rock mass models at Brunswick Mine

“…An interesting development is the use of the synthetic rock mass (SRM) approach to link fracture systems to PFC3D models [22]. Engineering applications include investigations on the interaction of stress and structure on the stability of vertical excavations [23] and the influence of scale effects on the calculated mechanical properties of rock masses [24][25][26]. An advantage of using particle flow code over some other distinct element models is the possibility to simulate fracture propagation in the rock mass.…”

Where do the data come from?

“…An approach that merits further attention is using the Synthetic Rock Mass (SRM) of large scale samples to determine the strength of rock masses. This has been used with some success by Cundall et al (2008), Esmaieli et al (2010), Stead (2010) andMas Ivars et al (2011). Figure 9 illustrates a generated SRM for Brunswick Mine.…”