Developing a ground model: borehole logging exercise

Question 1

Why do we need ground investigation?

Answer 1

To check:
- Suitability of the site for the proposed project;
- Site conditions and ground properties;
- Potential geotechnical/geological issues;
- Ground characterisation.

Question 2

What’s part of the initial stage of the ground investigation?

Answer 2

• Desk study of available data
• Walkover survey and visual assessment
• Preliminary report and scope of works

Question 3

What is part of the MainStage of the ground investigation?

Answer 3

• Field work (geological mapping, geophysics, test pits, boreholes/coring)
• Laboratory testing (soils and rocks)
• Final report

Question 4

What’s the last stage in ground investigation?

Answer 4

Monitoring

Question 5

What are boreholes purpose?

Answer 5

Boreholes extract a length of soil and/or rock from the earth - investigating soil and rock properties

Question 6

What happens after boreholes are extracted?

Answer 6

Samples taken from the site are examined either on site or back in the laboratory.

Question 7

What are the 3 distinctive characteristics in the description of rocks?

Answer 7

Material Characteristics
Discontinuity Characteristics
Mass Characteristics

Question 8

What items are recorded in core logging?

Answer 8

• Inclination
• Roughness
• Surface condition/colour

Question 9

Why is core logging important?

Answer 9

Used for geological analysis

Question 10

What is weathering caused by?

Answer 10

Weathering is caused by water, ice, acids, salts, plants, animals, changes in temperature and wind.

Question 11

What are some fractures in cores?

Answer 11

• Joints
• Mechanical breaks
• Rubble zones

Question 12

How do you calculate the RQD?

Answer 12

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.

Question 13

What types of joint roughness are there?

Answer 13

• Stepped slickensided
• Stepped rough
• Undulating rough
• Undulating slickensided
• Planar slickensided
• Planar rough

Question 14

What is joint aperture?

Answer 14

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