Lecture 2 - Factual and Interpretive Reporting Flashcards
What does BS5930: 1999 indicate?
Basic principles of how rocks should be described
Particular order
What three decisions must be made for soil descriptions? (NOTE: Opposite from order or words)
Principal soil type
Secondary and minor fractions
Other features
How do you distinguish silt from clay using the dry strength technique?
Roll a moistened sample into a thread/ribbon
Air dry
Crumble
SILT will crumble easily, CLAY will not
How do you distinguish silt from clay using the dilatancy technique?
Place sample in one hand, palm up
Add water to form a putty
With empty hand, pat sample hand for 5-10 secs
If water rises to surface = SILT
what two types of laboratory tests are undertaken and what do they test for?
Geotechnical - classification, shear/compressive strength
Environmental - sulphate, pH, metals
How is moisture content worked out? What happens to sample before test?
Sample dried in oven
p=(W-D)/D
p = fraction of total evaporable moisture content of sample, W = mass of original sample, D = mass of dried sample
How is particle size distribution carried out?
Sieve analysis
What are Atterberg limits?
Depending on water content, soil is solid, semi-solid, plastic or liquid
What is meant by plastic and liquid limit?
Plastic limit = where soil becomes plastic
Liquid Limit = where soil becomes liquid
What is the plasticity index? How is it worked out?
Measure of plasticity
Its difference between Liquid limit and Plastic limit
Give an example of a chemical classification?
pH
How is the California bearing ratio calculated? What does it measure?
Measures compaction
Pressure to penetrate soil sample with standard plunger, divided by pressure to penetrate a standard crushed rock
How is shear strength calculated?
Unconfined compressive strength
How does uniaxial shearing occur? What does it measure?
Soil sample cylinder compressed between two plates
Measures maximum load at failure
How is shear strength of soil tested under controlled drainage conditions?
Triaxial test