Glossary of logging terms
The words that GeotechOS Borehole Logging uses, from AS 1726-2017 terms such as TCR, RQD and SPT to app terms such as hold, sync and legend.
Applies toWindows and macOSWeb browserPhone and tablet
This page explains the words and abbreviations that GeotechOS Borehole Logging uses. The geotechnical terms follow AS 1726-2017, Geotechnical site investigations.
Geotechnical terms
| Term | Meaning |
|---|---|
| AHD | Australian Height Datum. The level that RLs in Australia are measured from. |
| Borehole | A hole drilled into the ground to log it, sample it and test it. |
| CBR | California bearing ratio. A measure of the strength of a subgrade. Borehole Logging gets it from DCP tests. |
| Consistency | How firm a fine-grained soil (clay or silt) is: very soft (VS), soft (S), firm (F), stiff (St), very stiff (VSt) or hard (H). |
| Core run | One length of rock core that the drill brings up at one time. |
| Cored hole | A borehole, or the part of it, that is drilled with a core barrel to bring up rock core. |
| DCP | Dynamic cone penetrometer. A test that counts the blows to drive a cone each 100 mm. |
| Defect | A break or a weakness in rock, for example a joint (JT), a bedding parting (BP) or a crushed zone (CZ). |
| Defect spacing | The distance between the defects in a length of core, in millimetres. |
| Density | How tightly a coarse-grained soil (sand or gravel) is packed: very loose (VL), loose (L), medium dense (MD), dense (D) or very dense (VD). |
| Fill | Ground that people put in place, for example made ground or road base. |
| Group symbol | The soil class of the Unified Soil Classification System, for example CL for a low plasticity clay. |
| Groundwater | Water in the ground. The log shows where water came into the hole and the level that it rose to. |
| Is50 | The point load strength index of rock, in MPa. |
| Lithology | The description of the soil and rock in each layer (stratum). |
| MGA | Map Grid of Australia. The easting and northing of a hole, in a zone, for example MGA2020 Zone 56. |
| Moisture condition | How wet a soil is. For a coarse soil: dry (D), moist (M) or wet (W). For a fine soil, compared with the plastic limit: drier than (w < PL), about (w ≈ PL) or wetter than (w > PL). |
| N, N60, (N1)60 | The SPT blow count for 300 mm (N), corrected to 60 % of the hammer energy (N60), and also corrected for the overburden pressure ((N1)60). |
| PP | Pocket penetrometer. A hand test of the strength of a clay, in kPa. |
| Refusal | The drill or the test cannot go deeper. An SPT that stops before 300 mm is a refusal, for example 25/100 mm. |
| RL | Reduced level. The level of a point, in metres above the datum, for example 24.35 m AHD. |
| RQD | Rock quality designation. The total length of the pieces of core that are 100 mm or longer, as a percentage of the core run. |
| SCR | Solid core recovery. The length of solid core, as a percentage of the core run. |
| SPT | Standard penetration test. The blows to drive a split spoon sampler in three steps of 150 mm. The first step is the seating drive. N is the blows of the last two steps. |
| Stratum | One layer of soil or rock, with a top depth and a bottom depth. |
| Strength (rock) | Very low (VL), low (L), medium (M), high (H), very high (VH) or extremely high (EH). |
| TCR | Total core recovery. The length of core that the drill brought up, as a percentage of the core run. |
| Test pit | A pit dug with an excavator or by hand to log and sample the ground. |
| UCS | Uniaxial compressive strength of rock, in MPa, from a laboratory test. |
| VST | Vane shear test. A test of the undrained shear strength of a soft clay, in kPa. |
| Weathering | How much rock has changed: residual soil (RS), extremely (XW), highly (HW), moderately (MW), slightly (SW) weathered, or fresh (FR). Distinctly weathered (DW) is HW or MW when you cannot tell them apart. |
Borehole Logging terms
| Term | Meaning |
|---|---|
| AGS 4 | The file format for geotechnical data from the Association of Geotechnical and Geoenvironmental Specialists. Borehole Logging imports and exports it. |
| Alignment | The centreline of a road or a pipeline. It gives each hole a chainage and an offset. |
| Bottom panel | The panel under the table: Checks, the Detail or Description of the row, and the Field sheet. |
| Chainage | The distance along an alignment or a section line, in metres. |
| Check | Something in a hole that is wrong or not finished, in the Checks panel. |
| Corridor | The distance from a section line in which holes show on the section. |
| Cross-section | A drawing of the holes along a line, with the ground units between them. |
| Desktop workspace | Borehole Logging on Windows, macOS or in a web browser: the ribbon, the project tree and the tables. |
| Fence diagram | The cross-sections of a project stood up together in 3D. |
| Field logger | Borehole Logging on a phone or a tablet. |
| Field sheet | The scan of the log that the logger wrote by hand on site. |
| Geology unit | A name for a group of strata that belong together, for example Qa for alluvium. Sections and the 3D view join strata on their unit. |
| Hold | When one device edits a hole, it holds the hole. Other devices cannot change the hole until the hold stops. |
| Hole | A borehole or a test pit. |
| Investigation | One stage of work in a project, with its holes. |
| Layout issue | A problem that stops Borehole Logging from drawing a log sheet correctly. |
| Legend | The graphic pattern of a stratum on the log, for example the pattern for sandy clay. |
| Log sheet | The printed log of a hole. |
| Project | A site or a job, with its investigations, holes, sections and plans. |
| Sheet template | The layout of a log sheet: its titles, columns, wording and scales. |
| Strip | The live column of the open hole, drawn beside the table. |
| Sync | Borehole Logging sends your changes to the server and gets the changes of other people. |