Classification type name

Description

Aperture / Width

Aperture is the perpendicular distance between adjacent rock walls of a discontinuity, in which the intervening space is air or water filled.

Aperture is thereby distinguished from the width of a filled discontinuity. For a filled discontinuity the width describes also the thickness of the filling. [5]

This classification is used to describe a discontinuity of this discontinuity unit regarding to the aperture or width (whichever is fitting in the context where the classification is used)

Clay alteration

Clayband

Discontinuity count

Number of discontinuities (for a discontinuity set)

Discontinuity group

Classification for discontinuities according to common characteristics.

Exposureline

Filling

Filling is the material that separates the adjacent rock walls of a discontinuity and that is usually weaker than the parent rock. Typical filling materials are sand, silt, clay, breccia, gouge, mylonite. Also includes thin mineral coatings and healed discontinuities, e.g. quartz and calcite veins. [5]

This classification is used to classify the discontinuity filling.

Genesis

Classification of discontinuities according to their genesis.
 

Joint distance

Lineare-Type

Permeability

Classification for the discontinuity trace length as observed in an exposure. May give a crude measure of the areal extent or penetration length of a discontinuity. Termination in solid rock or against other discontinuities

Persistence

The persistence is the discontinuity trace length as observed in an exposure. May give a crude measure of the areal extent or penetration length of a discontinuity. Termination in solid rock or against other discontinuities reduces the persistence [5]

The persistence determines the possibilities of relative movement along a discontinuity in a soil or rock mass.

This classification type is used to classify discontinuities regarding to their persistence.

Rockbonding

Roughness

Classification of discontinuities according to the inherent surface roughness and waviness relative to the mean plane of a discontinuity. Both roughness and waviness contribute to the shear strength. Large scale waviness may also alter the dip locally. [5]

Shear

Spacing

Classification of discontinuities according to the perpendicular distance between adjacent discontinuities. Normally refers to the mean or modal spacing of a set of joints. [5]

Surface

Classification for the description of the macroscopic structure of the discontinuity wall, e.g. undulating

Wall strength

Classification of discontinuities according to the equivalent compression strength of the adjacent rock walls. May be lower than rock block strength due to weathering or alteration of the walls. An important component of shear strength if rock walls are in contact.[5]

Water flow

Classification of water inflow according to the amount of water flowing inside the discontinuity.

Weakness zone thickness