Types of samples and samplers in Geotechnical engineering

1. Presentation On
Types of samples and samplers in
Geotechnical engineering
Submitted by :
Name –Indranil Banerjee
Roll no –CEM18005
DEPARTMENT OF CIVIL ENGINEERING
TEZPUR UNIVERSITY
AUTUMN, 2018

2. CONTENT:
INTRODUCTION
TYPES 0F SAMPLE
• Disturbed sample
• Undisturbed sample
 SAMPLE DISTURBANCE
• Area ratio
• Inside clearance
• Outside clearance
TYPES OF SAMPLER
• Open drive sampler
• Piston sampler
• Rotary sampler
REFERENCE

3. INTRODUCTION
 SOIL SAMPLING : Soil sampling is the method of collecting in–situ soil sample
by different method in view of performing laboratory investigation to
determine engineering properties of soil.
 SAMPLES : In geotechnical engineering soil sample is collected to learn about
the properties of the strata below the ground surface .
 SAMPLER : Device used for sampling are known as soil sampler.

4. TYPES OF SAMPLE :
disturbed sample : Disturbed sample are of two types:
(A) Representative sample: Natural water content ,mineral are preserved
but the soil structure get altered
SAMPLE
DISTURBED
SAMPLE
UNDISTURBED
SAMPLE
NON-
REPRESENTATIVE
SAMPLE
REPRESENTATIVE
SAMPLE

5. (B) Non-Representative sample: Physical structure get altered but also there will
be alternation in natural water content and minerals constituents.
 UNDISTURBED SAMPLE: Physical structure of the soil and its mineral constituents
and natural water content are preserved.
Fig-Undisturbed soil sample

6. SAMPLE DISTURBANCE:
Sample disturbance depends on the type of sampler and is measured in terms of
three parameters.
 Area ratio
 Inside clearance
 Outside clearance
Area ratio: It should be low as possible ,not more
than 20% in stiff formation and 10% for
sensitive clay.
Ar =(
𝐷 𝑐𝑜
2
−𝐷𝑐𝑖2
𝐷 𝑐𝑖
2 ) ∗ 100
.

7. Inside clearance: Inside diameter of the sampling tube is more
than the cutting edge , it reduces the friction between samples and
wall of sampling tube .It should be in between 1%-3%.
I c= (
𝐷 𝑠𝑖
−𝐷𝑐𝑖
𝐷 𝑐𝑖
) *100
Outside clearance: The outside diameter of the cutting edge
is higher than that of sampling tube , it help easy withdrawal of the
sampler. It should lie between 0%-2%.
Oc= (
𝐷 𝑐𝑜
−𝐷𝑠𝑜
𝐷 𝑠𝑜
) *100
Recovery ratio:
𝐴𝑐𝑡𝑢𝑎𝑙 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑎𝑚𝑝𝑙𝑒 𝑖𝑛 𝑡ℎ𝑒 𝑡𝑢𝑏𝑒
𝑃𝑒𝑛𝑒𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑡ℎ𝑒 𝑠𝑎𝑚𝑝𝑙𝑒𝑟
Rr=1
Rr>1
Rr<1

8. TYPES OF SAMPLER:
 Open drive sampler: Open drive sample
Is use to collect both disturbed (Representative) sample
and undisturbed sample.
Opendrivesampler
Thick walled sampler
Thin wall sampler

9. (A) Thick walled sampler:
FIG- Thick wall sampler (Split spoon sampler)
CUTTING
EDGE SAMPLING
TUBE
VENT

10. (B) Thin walled sampler:
FIG- Thin walled sample (shellby tube sampler)

11.  Pistonsampler :
FIG - Piston Sampler(Undisturbed sample))
FIG- Sample from piston sampler

12. Rotary sampler:
It is double wall tube sampler, consist of inner tube and outer tube or rotating barrel ,the
rotating barrel consist of cutting bit which rotated and the bits cuts an annular ring, which
then collected in the inner tube by the rotary barrel.
FIG – ROTARY SAMPLER

13. Rock Recovery ratio=
𝑇𝑜𝑡𝑎𝑙 𝑙𝑒𝑛𝑔ℎ𝑡ℎ 𝑜𝑓 𝑐𝑜𝑟𝑒 𝑟𝑒𝑐𝑜𝑣𝑒𝑟𝑒𝑑
𝑃𝑒𝑛𝑒𝑡𝑟𝑎𝑡𝑖𝑜𝑛 𝑙𝑒𝑛𝑔ℎ𝑡 𝑜𝑓 𝑠𝑎𝑚𝑝𝑙𝑒𝑟 * 100
TABLE- ROCK QUALITY DESIGNATION CHART
RQD % ROCK QUALITY
<25 VERY POOR
25-50 POOR
50-75 FAIR
75-90 GOOD
90-100 EXCELLENT

14. REFERENCE :
1) Basic and applied soil mechanics –Gopal Ranjan and A.S.R Rao.
2) Foundation analysis and Design –Joseph E. Bowles.
3) https://en.wikipedia.org/wiki/Geotechnical_investigation
4) https://www.scribd.com/document/117745153/Types-of-Samplers
5) Google Image.