1 30 Discontinuities

JRC

1

3

I

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I

7

9

11

13

1s

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19

0 5 10 cm

I I I I I8 I, II

Scale

Figure 7.16 Barton’s Joint Roughness Coefficient profiles. Note reduced scale.

simulations of sufficiently similar synthetic rock masses. Perhaps we can

use well-known statistical techniques to answer such questions as, ‘How

long should a scanline be such that a reliable estimate of the mean

discontinuity spacing value is obtained?’ We have found, as discussed

earlier, that the Poisson process and the associated negative exponential

spacing distribution are good theoretical models for discontinuity

occurrence, so it is appropriate to begin this explanation of the value of

statistical techniques with the Poisson process.

Poisson process. Describing rock mass structure in terms of the Poisson

process (and hence implicitly assuming that the position of a discontinuity