Developing a ground model: borehole logging exercise Flashcards
Why do we need ground investigation?
To check:
- Suitability of the site for the proposed project;
- Site conditions and ground properties;
- Potential geotechnical/geological issues;
- Ground characterisation.
What’s part of the initial stage of the ground investigation?
- Desk study of available data
- Walkover survey and visual assessment
- Preliminary report and scope of works
What is part of the MainStage of the ground investigation?
- Field work (geological mapping, geophysics, test pits, boreholes/coring)
- Laboratory testing (soils and rocks)
- Final report
What’s the last stage in ground investigation?
Monitoring
What are boreholes purpose?
Boreholes extract a length of soil and/or rock from the earth - investigating soil and rock properties
What happens after boreholes are extracted?
Samples taken from the site are examined either on site or back in the laboratory.
What are the 3 distinctive characteristics in the description of rocks?
Material Characteristics
Discontinuity Characteristics
Mass Characteristics
What items are recorded in core logging?
- Inclination
- Roughness
- Surface condition/colour
Why is core logging important?
Used for geological analysis
What is weathering caused by?
Weathering is caused by water, ice, acids, salts, plants, animals, changes in temperature and wind.
What are some fractures in cores?
- Joints
- Mechanical breaks
- Rubble zones
How do you calculate the RQD?
The RQD is a modified core recovery percentage in which all the pieces of sound core over 100 mm (4 in.) long are summed and divided by the length of the core run.
What types of joint roughness are there?
- Stepped slickensided
- Stepped rough
- Undulating rough
- Undulating slickensided
- Planar slickensided
- Planar rough
What is joint aperture?
Aperture is the perpendicular distance separating the adjacent rock walls of an open discontinuity, in which the intervening space is air or water filled.
