Geotechnical Dictionary

Comprehensive searchable dictionary of geotechnical terms, classifications, and standards for rock strength, weathering, soil properties, and more.

Geotechnical Dictionary - Complete Classification Reference

Comprehensive dictionary of geotechnical terms, classifications, and standards including rock strength, weathering, soil consistency classifications from AS 1726:2017 and CoalLog standards.

Material Alteration Classifications

Extremely Altered (XA) - AS 1726

Material is altered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are still visible.

Highly Altered (HA) - AS 1726

The whole of the rock material is discoloured, usually by staining or bleaching to the extent that the colour of the original rock is not recognisable. Rock strength is changed by alteration. Some primary minerals are altered to clay minerals. Porosity may be increased by leaching, or may be decreased due to precipitation of secondary minerals in pores.

Moderately Altered (MA) - AS 1726

The whole of the rock material is discoloured, usually by staining or bleaching to the extent that the colour of the original rock is not recognisable but shows little or no change of strength from fresh rock.

Disctinctly Altered (DA) - AS 1726

The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable, but shows little or no change of strength from fresh rock.

Slightly Altered (SA) - AS 1726

Where it is not practicable to distinguish between Highly Weathered and Moderately Weathered rock the term Distinctly Weathered may be used. Distinctly Weathered is defined as follows: Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores. There is some change in rock strength.

Extremely Altered (E) - CoalLog

Rock is altered to such an extent that it has soil properties, i.e., it either disintegrates or can be remoulded, in water.

Distinctly Altered (D) - CoalLog

Rock strength and mineralogy usually changed by alteration. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores.

Slightly Altered (S) - CoalLog

Rock is slightly discoloured but shows little or no change of strength from fresh rock. Usually penetrative alteration along defect surfaces.

Altered (A) - CoalLog

Degree of alteration not assessed.

Fresh (F) - CoalLog

Rock shows no sign of decomposition or staining.

Material Strength Classifications

Very Soft (C1) - CoalLog

Exudes between the fingers when squeezed in hand [Undrained shear strength (su) <12 kPa].

Soft (C2) - CoalLog

Can be moulded by light finger pressure [Undrained shear strength (su) 12-25 kPa].

Firm (C3) - CoalLog

Can be moulded by strong finger pressure [Undrained shear strength (su) 25-50 kPa].

Stiff (C4) - CoalLog

Cannot be moulded by fingers, can be indented by thumb [Undrained shear strength (su) 50-100 kPa].

Very Stiff (C5) - CoalLog

Can be indented by thumb nail [Undrained shear strength (su) 100-200 kPa].

Hard (C6) - CoalLog

Can be indented with difficulty by thumbnail [Undrained shear strength (su) >200 kPa].

Very Loose (S1) - CoalLog

Easily dissociated with flicks of finger nail [Relative density (Dr) <15%].

Loose (S2) - CoalLog

Easily penetrated by knife blade, readily dissociated by scratching with finger nail [Relative density (Dr) 15-35%].

Medium Dense (S3) - CoalLog

Penetrated by knife only with firm pressure, readily indented by thumb pressure, dissociated with difficulty by scratching with finger nail [Relative density (Dr) 35-65%].

Dense (S4) - CoalLog

Difficult to indent by thumb pressure, dissociated readily by knife blade [Relative density (Dr) 65-85%].

Very Dense (S5) - CoalLog

Cannot be indented by thumb pressure; Dissociated only by firm pressure with knife blade [Relative density (Dr) >85%].

Extremely Low Strength Rock (R1) - CoalLog

May be broken by hand and remoulded (with the addition of water if necessary) to a material with soil properties [UCS <1 MPa].

Very Low Strength Rock (R2) - CoalLog

Crumbles under a single firm hammer blow; Can be peeled with a knife [UCS 1-5 MPa].

Low Strength Rock (R3) - CoalLog

Breaks under a single firm hammer blow; Scored but not peeled with a knife [UCS 5-10 MPa].

Medium Strength Rock (R4) - CoalLog

Breaks under 1 to 3 hammer blows; Can be scratched but not scored with a knife [UCS 10-25 MPa].

High Strength Rock (R5) - CoalLog

Breaks under 3 to 5 hammer blows; Hard to scratch with a knife; Can be scratched with tungsten-tipped tool; Hard sound when struck with hammer [UCS 25-50 MPa].

Very High Strength Rock (R6) - CoalLog

Breaks under 1 hammer blow if resting on solid surface; Cannot be scratched by knife; Scratched with difficulty by a tungsten-tipped tool; Dull ringing sound when struck with hammer [UCS 50-100 MPa].

Extremely High Strength Rock (R7) - CoalLog

Difficult to break with hammer even if resting on solid surface; Bright ringing sound when struck with hammer [UCS >100 MPa].

Very Soft (VS) - AS 1726

Exudes between the fingers when squeezed in hand [Undrained shear strength (su) <12 kPa].

Su Range: 0 - 12 kPa

Soft (S) - AS 1726

Can be moulded by light finger pressure [Undrained shear strength (su) 12-25 kPa].

Su Range: 12 - 25 kPa

Firm (F) - AS 1726

Can be moulded by strong finger pressure [Undrained shear strength (su) 25-50 kPa].

Su Range: 25 - 50 kPa

Stiff (St) - AS 1726

Cannot be moulded by fingers [Undrained shear strength (su) 50-100 kPa].

Su Range: 50 - 100 kPa

Very Stiff (VSt) - AS 1726

Can be indented by thumb nail [Undrained shear strength (su) 100-200 kPa].

Su Range: 100 - 200 kPa

Hard (H) - AS 1726

Can be indented with difficulty by thumb nail [Undrained shear strength (su) >200 kPa].

Su Range: 200 - 2000000 kPa

Friable (Fr) - AS 1726

Can be easily crumbled or broken into small pieces by hand.

Very Loose (VL) - AS 1726

Relative density (Dr) <15%.

RD Range: 0 - 15%

Loose (L) - AS 1726

Relative density (Dr) 15-35%.

RD Range: 15 - 35%

Medium Dense (MD) - AS 1726

Relative density (Dr) 35-65%.

RD Range: 35 - 65%

Dense (D) - AS 1726

Relative density (Dr) 65-85%.

RD Range: 65 - 85%

Very Dense (VD) - AS 1726

Relative density (Dr) >85%.

RD Range: 85 - 100%

Very Low Strength (VL) - AS 1726

Material crumbles under firm blows with sharp end of pick; can be peeled with knife; too hard to cut a triaxial sample by hand. Pieces up to 30 mm thick can be broken by finger pressure [UCS 0.6-2 MPa; PLT Is(50) 0.03-0.1 MPa].

Low Strength (L) - AS 1726

UCS 2 - 6 MPa; Easily scored with a knife; indentations 1 mm to 3 mm show in the specimen with firm blows of the pick point; has dull sound under hammer. A piece of core 150 mm long by 50 mm diameter may be broken by hand. Sharp edges of core may be friable and break during handling [UCS 2-6 MPa; PLT Is(50) 0.1-0.3 MPa].

Medium Strength (M) - AS 1726

Readily scored with a knife; a piece of core 150 mm long by 50 mm diameter can be broken by hand with difficulty [UCS 6-20 MPa; PLT Is(50) 0.3-1 MPa].

High Strength (H) - AS 1726

A piece of core 150 mm long by 50 mm diameter cannot be broken by hand but can be broken by a pick with a single firm blow; rock rings under hammer [UCS 20-60 MPa; PLT Is(50) 1-3 MPa].

Very High Strength (VH) - AS 1726

Hand specimen breaks with pick after more than one blow; rock rings under hammer [UCS 60-200 MPa; PLT Is(50) 3-10 MPa].

Extremely High Strength (EH) - AS 1726

Specimen requires many blows with geological pick to break through intact material; rock rings under hammer [UCS >200 MPa; PLT Is(50) >10 MPa].

Material Weathering Classifications

Residual Soil (RS) - AS 1726

Material is weathered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are no longer visible, but the soil has not been significantly transported.

Extremely Weathered (XW) - AS 1726

Material is weathered to such an extent that it has soil properties. Mass structure and material texture and fabric of original rock are still visible.

Highly Weathered (HW) - AS 1726

The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable. Rock strength is significantly changed by weathering. Some primary minerals have weathered to clay minerals. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores.

Moderately Weathered (MW) - AS 1726

The whole of the rock material is discoloured, usually by iron staining or bleaching to the extent that the colour of the original rock is not recognisable, but shows little or no change of strength from fresh rock.

Distinctly Weathered (DW) - AS 1726

Where it is not practicable to distinguish between Highly Weathered and Moderately Weathered rock the term Distinctly Weathered may be used. Distinctly Weathered is defined as follows: Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores. There is some change in rock strength.

Slightly Weathered (SW) - AS 1726

Rock is partially discoloured with staining or bleaching along joints but shows little or no change of strength from fresh rock.

Fresh (FR) - AS 1726

Rock shows no sign of decomposition of individual minerals or colour changes.

Residual Soil (R) - CoalLog

Soil developed on extremely weathered rock. The mass structure and substance fabric are no longer evident. There is a large change in volume but the soil has not been significantly transported

Extremely Weathered (E) - CoalLog

Rock is weathered to such an extent that it has soil properties, i.e., it either disintegrates or can be remoulded, in water.

Disctinctly Weathered (D) - CoalLog

Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining. Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores

Slightly Weathered (S) - CoalLog

Rock is slightly discoloured but shows little or no change of strength from fresh rock. Usually penetrative weathering along defect surfaces

Fresh (F) - CoalLog

Rock shows no sign of decomposition or staining

Colour Classifications

Black (K) - CoalLog

Blue (L) - CoalLog

Brown (B) - CoalLog

Buff (F) - CoalLog

Cream (C) - CoalLog

Green (E) - CoalLog

Grey (G) - CoalLog

Multi-Coloured (M) - CoalLog

Off-White (X) - CoalLog

Orange (O) - CoalLog

Pink (P) - CoalLog

Purple (U) - CoalLog

Red (R) - CoalLog

White (W) - CoalLog

Yellow (Y) - CoalLog

Defect Continuity Classifications

Continuous Across Core Width (C) - CoalLog

TBC

Discontinuous Across Core Width (D) - CoalLog

TBC

Divaricates (V) - CoalLog

TBC

Truncated Within Core Width (T) - CoalLog

TBC

Defect Infill Type Classifications

Apatite (AP) - CoalLog

White to grey green globular masses or reniform at times with a subfibrous, scaly, or imperfectly columnar structure or as fibrous crusts.

Calcite (CA) - CoalLog

Usually white but can also be colourless, grey, red, green, blue, yellow, brown, orange. White streak, vitreous lustre. Perfect rhombohedral cleavage. Low Mohs hardness (3). Dissolves in cold dilute HCl.

Carbonaceous Remains (XR) - CoalLog

Plant fragments that have undergone some form of coalification.

Carbonate (CB) - CoalLog

White in colour. Soft and brittle. Fizzes violently with diluted HCl.

Chlorite (CO) - CoalLog

Varying shades of green, yellow, pink - usually lightly coloured. Vitreous to pearly lustre. Perfect basal cleavage. Relatively soft (2-2.5).

Clay (CL) - CoalLog

Very fine grained sediment with platy minerals. Soft.

Coal (CO) - CoalLog

Carbon rich mineral deposit formed from the accumulation of organic matter and containing less than 50% ash yield on combustion; coal streaks brown (low rank) to black (high rank) when scratched with a metal tool.

Crushed Rock (CU) - CoalLog

Breccia.

Dickite (DI) - CoalLog

White or slightly tinted. Transparent. Waxy feel with a satiny lustre. Soft (2-2.5). Perfect cleavage.

Fossils (FO) - CoalLog

Umbrella term for the preserved traces or remains of organisms from the remote geological past.

Glauconite (GC) - CoalLog

Dark-olive green. Platy-micaceous mineral. Very soft (2). Indicative of shallow marine/coastal shelf environment.

Defect Intact Classifications

Intact (I) - CoalLog

Can be applied to any natural defect except for Broken Zone (BZ) or Coal Cleat (CE). Does not contribute to Rock Quality Designation (RQD).

Defect Roughness Classifications

Polished (P) - CoalLog

Smooth but without striations. Reflects light.

Rough (R) - CoalLog

Rough to touch. Sandpaper feel.

Slickensided (K) - CoalLog

striations visible on defect surface that may or may not be polished (the angle of the striations to the dip direction of the defect should be noted).

Smooth (S) - CoalLog

Smooth to feel but not polished or slickensided.

Defect Shape Classifications

Concave/Convex (C) - CoalLog

One trough or crest across the core width.

Irregular (I) - CoalLog

Many sharp troughs and crests in all directions across the core width.

Planar (P) - CoalLog

A surface with no obvious curves or irregularities across the core width.

Stepped (S) - CoalLog

Distinct steps in any direction across the core width.

Undulose (U) - CoalLog

Rounded crests and troughs in one or more directions across the core width.

Defect Spacing Classifications

Extremely Wide (EW) - CoalLog

Extremely wide defect spacing (<2 m).

Very Wide (VW) - CoalLog

Very wide defect spacing (600-2000 mm).

Wide (WI) - CoalLog

Wide defect spacing (200-600 mm).

Moderately Wide (MW) - CoalLog

Moderately wide defect spacing (60-200 mm).

Moderately Narrow (MN) - CoalLog

Moderately narrow defect spacing (20-60 mm).

Narrow (NA) - CoalLog

Narrow defect spacing (6-20 mm).

Very Narrow (VN) - CoalLog

Very narrow defect spacing (<6 mm).

Defect Type Classifications

Bedding Plane (BP) - CoalLog

Broken Zone (BZ) - CoalLog

Clay Band (CL) - CoalLog

Coal Cleat (CE) - CoalLog

Contraction Fracture (CF) - CoalLog

Cross-Bedding (XB) - CoalLog

Dyke (DY) - CoalLog

Fault (FT) - CoalLog

Foliation (FO) - CoalLog

Joint (JT) - CoalLog

Shear Zone (SH) - CoalLog

Sill (SI) - CoalLog

Softened Zone (Non-Tectonic) (SO) - CoalLog

Vein (VN) - CoalLog

Discing (DS) - CoalLog

Drilling Induced Break (DB) - CoalLog

Drilling Induced Broken Zone (DZ) - CoalLog

Hue Classifications

Blackish (K) - CoalLog

Bluish (B) - CoalLog

Brownish (B) - CoalLog

Buff (F) - CoalLog

Creamy (C) - CoalLog

Greenish (E) - CoalLog

Greyish (G) - CoalLog

Off-Whitish (X) - CoalLog

Orangey (O) - CoalLog

Pinkish (P) - CoalLog

Purplish (U) - CoalLog

Reddish (R) - CoalLog

Whitish (W) - CoalLog

Yellowish (Y) - CoalLog

Lithology Interrelation Classifications

Coarsening up to (CU) - CoalLog

Increase in grain size in sedimentary rock from base of the bed to its top. Termed reverse grading and is characteristic of some alluvial fan deposits.

Fining up to (FU) - CoalLog

Decrease in grain size in sedimentary rock from base of the bed to its top. Termed normal grading and is characteristic of some turbidites and many sedimentary beds deposited in waning flow conditions.

Interlaminated (<20 mm) with (IL) - CoalLog

Being positioned between or alternated with other laminations of dissimilar character where the layers are less then 20 mm thick.

Interbedded with (IB) - CoalLog

Being positioned between or alternated with other layers of dissimilar character.

Thinly interbedded (60-200 mm) with (UB) - CoalLog

TBC.

Very thinly interbedded (20-60 mm) with (UB) - CoalLog

TBC.

Coarsely interbedded (>200 mm) with (CB) - CoalLog

Being positioned between or alternated with other layers of dissimilar character where the layers are >200 mm thick.

Irregularly interbedded with (IR) - CoalLog

TBC.

Intercalated with (IB) - CoalLog

Existing or introduced between subordinate layers of a different type. It applies especially to layers of one kind of material that alternate with thicker strata of another material, e.g., Beds of shell intercalated with sandstone.

Intermixed with (IM) - CoalLog

Existing with lithology(s) of a different type in no regular fashion and not forming regular structures.

Disseminated with (DS) - CoalLog

Widely dispersed throughout rock.

With bands of (BN) - CoalLog

TBC.

With boulders of (BO) - CoalLog

TBC.

With cement of (CM) - CoalLog

TBC.

With clasts of (CT) - CoalLog

TBC.

With cobbles of (OO) - CoalLog

TBC.

With fragments of (FR) - CoalLog

TBC.

With granules of (GG) - CoalLog

TBC.

With lenses of (LN) - CoalLog

TBC.

With matrix of (MX) - CoalLog

TBC.

With nodules of (ND) - CoalLog

TBC.

With pebbles of (PB) - CoalLog

TBC.

With pods of (PO) - CoalLog

TBC.

With wisps of (WP) - CoalLog

TBC.

Plasticity Classification Classifications

Non-Plastic (N) - CoalLog

Visual-Tactile: Behaves as a cohesionless material which may exhibit a dilatancy reaction when shaken but which cannot be moulded into a plastic solid including being rolled into a 3 mm diameter thread. Laboratory: Either or both the Plastic Limit and Liquid Limit cannot be determined by the test methods.

Brittle (B) - CoalLog

Visual-Tactile: Behaves as a cohesive material but does not exhibit a dilatancy reaction and cannot be remoulded into a 3 mm thread. Laboratory: The Plastic Limit may or may not be measurable but the Liquid Limit cannot be measured by the test methods.

Low Plasticity (L) - CoalLog

Visual-Tactile: Behaves as a cohesive material, may or may not exhibit dilatancy, and feels smooth but gritty. Dried crumbs are easily broken down by finger pressure, dries rapidly from a thin film on a finder to a powdery consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is 35% or less. Can be subdivided into low plasticity silt (Plasticity Index below A-Line on Casagrande Plot) and low plasticity clay (Plasticity Index above A-Line on Casagrande Plot).

Intermediate Plasticity (I) - CoalLog

Visual-Tactile: Behaves as a cohesive material, may or may not exhibit dilatancy, and feels smooth. Dried crumbs can be ruptured with moderate finger pressure, dries slowly from a thin film on a finger to a cake consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is greater than 35% but not greater than 50%. Can be subdivided into intermediate plasticity silt and clay based on position relative to A-Line on Casagrande Plot.

High Plasticity (H) - CoalLog

Visual-Tactile: Behaves as a cohesive material, will not readily exhibit dilatancy, and feels very smooth like butter or grease. Dried crumbs are difficult to rupture with strong finger pressure, dries very slowly and in a sticky manner from a thin film on a finger to a hard cake consistency. Laboratory: Has measureable Plastic and Liquid Limits and the Liquid Limit is greater than 50%. Can be subdivided into high plasticity silt and clay based on position relative to A-Line on Casagrande Plo .

Rock Mass Unit Type Classifications

Broken Zone (B) - CoalLog

Zone greater than 200 mm with numerous defects, and individual defects are difficult to delineate.

Core Loss (L) - CoalLog

Core drilling but no core returned.

Core with Defects (D) - CoalLog

Individual defects can be identified and described.

Not Recorded (N) - CoalLog

No geotechnical information has been recorded for the unit.

Open Hole Drilling (O) - CoalLog

Only chip returns. Only geotechnical information possibly available is weathering and estimated strength.

Soil Properties (S) - CoalLog

Unconsolidated material.

Unbroken Core (U) - CoalLog

Core not containing any natural discontinuities.

Shade Classification Classifications

Light (L) - CoalLog

Light to Medium (A) - CoalLog

Light to Dark (C) - CoalLog

Medium (E) - CoalLog

Medium to Dark (B) - CoalLog

Dark (D) - CoalLog

Banded (N) - CoalLog

Mottled (M) - CoalLog

Speckled (S) - CoalLog

Variegated (V) - CoalLog

Sample Purpose Classifications

Raw Ply (Coal, Roof, Floor or Parting) (QP) - CoalLog

Bulk Sample (QB) - CoalLog

Channel Sample (Underground) (QU) - CoalLog

Raw Ply (Coal, Roof, Floor or Parting) (LP) - CoalLog

Raw Ply (Coal, Roof, Floor or Parting) (SP) - CoalLog

Bulk Sample (SB) - CoalLog

Channel Sample (SU) - CoalLog

Laboratory Tested (GT) - CoalLog

Field Tested (GF) - CoalLog

Laboratory Tested (WT) - CoalLog

Field Tested (WF) - CoalLog

Exploration (Virgin) (ME) - CoalLog

Compliance (Drained) (MD) - CoalLog

Soil (ES) - CoalLog

Overburden Characterisation (Compliance) (EO) - CoalLog

Reactive Ground (ER) - CoalLog

Age Dating (AD) - CoalLog

Palynology (PN) - CoalLog

Petrology (PE) - CoalLog

201 results
CodeTermDescriptionSource
XA
Material is altered to such an extent that it has soil prope...
AS 1726
HA
The whole of the rock material is discoloured, usually by st...
AS 1726
MA
The whole of the rock material is discoloured, usually by st...
AS 1726
DA
The whole of the rock material is discoloured, usually by ir...
AS 1726
SA
Where it is not practicable to distinguish between Highly We...
AS 1726
E
Rock is altered to such an extent that it has soil propertie...
CoalLog
D
Rock strength and mineralogy usually changed by alteration. ...
CoalLog
S
Rock is slightly discoloured but shows little or no change o...
CoalLog
A
Degree of alteration not assessed.
CoalLog
F
Rock shows no sign of decomposition or staining.
CoalLog
C1
Exudes between the fingers when squeezed in hand [Undrained ...
CoalLog
C2
Can be moulded by light finger pressure [Undrained shear str...
CoalLog
C3
Can be moulded by strong finger pressure [Undrained shear st...
CoalLog
C4
Cannot be moulded by fingers, can be indented by thumb [Undr...
CoalLog
C5
Can be indented by thumb nail [Undrained shear strength (su)...
CoalLog
C6
Can be indented with difficulty by thumbnail [Undrained shea...
CoalLog
S1
Easily dissociated with flicks of finger nail [Relative dens...
CoalLog
S2
Easily penetrated by knife blade, readily dissociated by scr...
CoalLog
S3
Penetrated by knife only with firm pressure, readily indente...
CoalLog
S4
Difficult to indent by thumb pressure, dissociated readily b...
CoalLog
S5
Cannot be indented by thumb pressure; Dissociated only by fi...
CoalLog
R1
May be broken by hand and remoulded (with the addition of wa...
CoalLog
R2
Crumbles under a single firm hammer blow; Can be peeled with...
CoalLog
R3
Breaks under a single firm hammer blow; Scored but not peele...
CoalLog
R4
Breaks under 1 to 3 hammer blows; Can be scratched but not s...
CoalLog
R5
Breaks under 3 to 5 hammer blows; Hard to scratch with a kni...
CoalLog
R6
Breaks under 1 hammer blow if resting on solid surface; Cann...
CoalLog
R7
Difficult to break with hammer even if resting on solid surf...
CoalLog
VS
Exudes between the fingers when squeezed in hand [Undrained ...
AS 1726
S
Can be moulded by light finger pressure [Undrained shear str...
AS 1726
F
Can be moulded by strong finger pressure [Undrained shear st...
AS 1726
St
Cannot be moulded by fingers [Undrained shear strength (su) ...
AS 1726
VSt
Can be indented by thumb nail [Undrained shear strength (su)...
AS 1726
H
Can be indented with difficulty by thumb nail [Undrained she...
AS 1726
Fr
Can be easily crumbled or broken into small pieces by hand.
AS 1726
VL
Relative density (Dr) <15%.
AS 1726
L
Relative density (Dr) 15-35%.
AS 1726
MD
Relative density (Dr) 35-65%.
AS 1726
D
Relative density (Dr) 65-85%.
AS 1726
VD
Relative density (Dr) >85%.
AS 1726
VL
Material crumbles under firm blows with sharp end of pick; c...
AS 1726
L
UCS 2 - 6 MPa; Easily scored with a knife; indentations 1 mm...
AS 1726
M
Readily scored with a knife; a piece of core 150 mm long by ...
AS 1726
H
A piece of core 150 mm long by 50 mm diameter cannot be brok...
AS 1726
VH
Hand specimen breaks with pick after more than one blow; roc...
AS 1726
EH
Specimen requires many blows with geological pick to break t...
AS 1726
RS
Material is weathered to such an extent that it has soil pro...
AS 1726
XW
Material is weathered to such an extent that it has soil pro...
AS 1726
HW
The whole of the rock material is discoloured, usually by ir...
AS 1726
MW
The whole of the rock material is discoloured, usually by ir...
AS 1726
DW
Where it is not practicable to distinguish between Highly We...
AS 1726
SW
Rock is partially discoloured with staining or bleaching alo...
AS 1726
FR
Rock shows no sign of decomposition of individual minerals o...
AS 1726
R
Soil developed on extremely weathered rock. The mass structu...
CoalLog
E
Rock is weathered to such an extent that it has soil propert...
CoalLog
D
Rock strength usually changed by weathering. The rock may be...
CoalLog
S
Rock is slightly discoloured but shows little or no change o...
CoalLog
F
Rock shows no sign of decomposition or staining
CoalLog
KNo description availableCoalLog
LNo description availableCoalLog
BNo description availableCoalLog
FNo description availableCoalLog
CNo description availableCoalLog
ENo description availableCoalLog
GNo description availableCoalLog
MNo description availableCoalLog
XNo description availableCoalLog
ONo description availableCoalLog
PNo description availableCoalLog
UNo description availableCoalLog
RNo description availableCoalLog
WNo description availableCoalLog
YNo description availableCoalLog
C
TBC
CoalLog
D
TBC
CoalLog
V
TBC
CoalLog
T
TBC
CoalLog
AP
White to grey green globular masses or reniform at times wit...
CoalLog
CA
Usually white but can also be colourless, grey, red, green, ...
CoalLog
XR
Plant fragments that have undergone some form of coalificati...
CoalLog
CB
White in colour. Soft and brittle. Fizzes violently with dil...
CoalLog
CO
Varying shades of green, yellow, pink - usually lightly colo...
CoalLog
CL
Very fine grained sediment with platy minerals. Soft.
CoalLog
CO
Carbon rich mineral deposit formed from the accumulation of ...
CoalLog
CU
Breccia.
CoalLog
DI
White or slightly tinted. Transparent. Waxy feel with a sati...
CoalLog
FO
Umbrella term for the preserved traces or remains of organis...
CoalLog
GC
Dark-olive green. Platy-micaceous mineral. Very soft (2). In...
CoalLog
I
Can be applied to any natural defect except for Broken Zone ...
CoalLog
P
Smooth but without striations. Reflects light.
CoalLog
R
Rough to touch. Sandpaper feel.
CoalLog
K
striations visible on defect surface that may or may not be ...
CoalLog
S
Smooth to feel but not polished or slickensided.
CoalLog
C
One trough or crest across the core width.
CoalLog
I
Many sharp troughs and crests in all directions across the c...
CoalLog
P
A surface with no obvious curves or irregularities across th...
CoalLog
S
Distinct steps in any direction across the core width.
CoalLog
U
Rounded crests and troughs in one or more directions across ...
CoalLog
EW
Extremely wide defect spacing (<2 m).
CoalLog
VW
Very wide defect spacing (600-2000 mm).
CoalLog
WI
Wide defect spacing (200-600 mm).
CoalLog
MW
Moderately wide defect spacing (60-200 mm).
CoalLog
MN
Moderately narrow defect spacing (20-60 mm).
CoalLog
NA
Narrow defect spacing (6-20 mm).
CoalLog
VN
Very narrow defect spacing (<6 mm).
CoalLog
BPNo description availableCoalLog
BZNo description availableCoalLog
CLNo description availableCoalLog
CENo description availableCoalLog
CFNo description availableCoalLog
XBNo description availableCoalLog
DYNo description availableCoalLog
FTNo description availableCoalLog
FONo description availableCoalLog
JTNo description availableCoalLog
SHNo description availableCoalLog
SINo description availableCoalLog
SONo description availableCoalLog
VNNo description availableCoalLog
DSNo description availableCoalLog
DBNo description availableCoalLog
DZNo description availableCoalLog
KNo description availableCoalLog
BNo description availableCoalLog
BNo description availableCoalLog
FNo description availableCoalLog
CNo description availableCoalLog
ENo description availableCoalLog
GNo description availableCoalLog
XNo description availableCoalLog
ONo description availableCoalLog
PNo description availableCoalLog
UNo description availableCoalLog
RNo description availableCoalLog
WNo description availableCoalLog
YNo description availableCoalLog
CU
Increase in grain size in sedimentary rock from base of the ...
CoalLog
FU
Decrease in grain size in sedimentary rock from base of the ...
CoalLog
IL
Being positioned between or alternated with other lamination...
CoalLog
IB
Being positioned between or alternated with other layers of ...
CoalLog
UB
TBC.
CoalLog
UB
TBC.
CoalLog
CB
Being positioned between or alternated with other layers of ...
CoalLog
IR
TBC.
CoalLog
IB
Existing or introduced between subordinate layers of a diffe...
CoalLog
IM
Existing with lithology(s) of a different type in no regular...
CoalLog
DS
Widely dispersed throughout rock.
CoalLog
BN
TBC.
CoalLog
BO
TBC.
CoalLog
CM
TBC.
CoalLog
CT
TBC.
CoalLog
OO
TBC.
CoalLog
FR
TBC.
CoalLog
GG
TBC.
CoalLog
LN
TBC.
CoalLog
MX
TBC.
CoalLog
ND
TBC.
CoalLog
PB
TBC.
CoalLog
PO
TBC.
CoalLog
WP
TBC.
CoalLog
N
Visual-Tactile: Behaves as a cohesionless material which may...
CoalLog
B
Visual-Tactile: Behaves as a cohesive material but does not ...
CoalLog
L
Visual-Tactile: Behaves as a cohesive material, may or may n...
CoalLog
I
Visual-Tactile: Behaves as a cohesive material, may or may n...
CoalLog
H
Visual-Tactile: Behaves as a cohesive material, will not rea...
CoalLog
B
Zone greater than 200 mm with numerous defects, and individu...
CoalLog
L
Core drilling but no core returned.
CoalLog
D
Individual defects can be identified and described.
CoalLog
N
No geotechnical information has been recorded for the unit.
CoalLog
O
Only chip returns. Only geotechnical information possibly av...
CoalLog
S
Unconsolidated material.
CoalLog
U
Core not containing any natural discontinuities.
CoalLog
LNo description availableCoalLog
ANo description availableCoalLog
CNo description availableCoalLog
ENo description availableCoalLog
BNo description availableCoalLog
DNo description availableCoalLog
NNo description availableCoalLog
MNo description availableCoalLog
SNo description availableCoalLog
VNo description availableCoalLog
QPNo description availableCoalLog
QBNo description availableCoalLog
QUNo description availableCoalLog
LPNo description availableCoalLog
SPNo description availableCoalLog
SBNo description availableCoalLog
SUNo description availableCoalLog
GTNo description availableCoalLog
GFNo description availableCoalLog
WTNo description availableCoalLog
WFNo description availableCoalLog
MENo description availableCoalLog
MDNo description availableCoalLog
ESNo description availableCoalLog
EONo description availableCoalLog
ERNo description availableCoalLog
ADNo description availableCoalLog
PNNo description availableCoalLog
PENo description availableCoalLog

What is a Geotechnical Dictionary?

A geotechnical dictionary is a comprehensive reference tool that provides standardised classifications, definitions, and terminology used in geotechnical engineering and geology. This resource consolidates various classification systems for rock strength, material weathering, soil properties, colour classifications, defect characteristics, plasticity, and other geological characteristics that are essential for engineering design, construction planning, and geological interpretation.

Key Classifications:

  • Rock Strength Classification - Standardised strength categories from very weak to very strong rock
  • Material Weathering - Systematic assessment of rock and soil decomposition states
  • Soil Consistency & Density - Classifications for cohesive and cohesionless soil properties
  • Colour & Hue Classifications - Standardised colour terminology for geological materials
  • Defect Properties - Comprehensive classification of defect types, spacing, continuity, roughness, and infill characteristics
  • Plasticity & Material Properties - Classification systems for soil plasticity and lithological relationships
  • Engineering Standards - Compliance with AS 1726, CoalLog, and international standards

Classification Standards

This dictionary includes classifications from recognised Australian and international standards:

AS 1726-2017

Geotechnical site investigations

  • Rock material strength classification
  • Material weathering classification
  • Soil consistency and density standards

CoalLog Standards

Coal industry specific classifications

  • Coal-specific rock strength terms
  • Mining-oriented weathering classifications
  • Specialised geological descriptions

How to Use This Tool

The geotechnical dictionary provides several ways to access and search classification data:

📝 Search Function

Use the search bar to find specific terms, codes, or descriptions across all classification categories.

📋 Category Tabs

Browse different classification categories including rock strength, weathering, soil properties, colour classifications, defect characteristics, plasticity, and more.

🔍 Detailed Descriptions

Each classification includes detailed descriptions, codes, and applicable standards.

📊 Quantitative Ranges

Where applicable, view numerical ranges for strength values and test parameters.

Applications

This geotechnical dictionary is valuable for:

Field Operations

  • Standardising terminology
  • Training field technicians and geologists
  • Ensuring consistent data recording
  • Quality control of activities

Engineering Design

  • Interpreting borehole logs
  • Converting field descriptions to design parameters
  • Understanding material classifications
  • Reviewing geotechnical reports

Data Sources & Standards

The classifications in this dictionary are based on established standards and guidelines:

Primary Standards:

  • AS 1726-2017 - Geotechnical site investigations (Australian Standard)
  • CoalLog Standards - Coal industry specific classifications and terminology
  • International Classifications - Recognised global standards for geological description

Important Notes

  • Classifications should be used in conjunction with appropriate Australian Standards and local guidelines.
  • Field logging should be performed by qualified geotechnical professionals with appropriate training and experience.
  • This tool provides reference information only and should not replace professional judgment in site-specific conditions.
  • Always verify classifications against the most current versions of relevant standards and specifications.

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