1. Site Investigation and Field Tests

2. Site investigation (SI) methods
Surface Grab Sampling
Boreholes (and sampling by SPT and tube)
Excavation and auger
Piezocone Penetration (CPTU)
Macintosh Probing
Field Density Test
Rock and Fracture Mapping
Geophysical Methods
Others?

3. Why Do We Carry Out Site Investigation
General Assessment and Design
Geotechnical Assessment of an EIA
Slope Stability Design
Foundation Design
Fill Assessment and Design
Embankment Design
Damn Design
Rock Slope Design
Rock Tunnel Design
Landfill Assessment and Design
Other reason?

4. In Situ Soil Testing Methods, by popularity in Malaysia
SPT in Boreholes
Macintosh Probing
Piezocone Penetration (CPTU)
Field Vane Shear
Field Density Test
And many more
Can you tell the difference between SI and In-Situ Test?

5. 1. SI by Surface Grab Sampling
Advantage
- Easy (and cheap)
Disadvantage
- Not representing sub-surface soils
Why?
For quick and preliminary information
To verify certain probing results

6. 2. SI by Bore Hole (and sampling by SPT and tube)
Advantage - Able to retrieve representative samples and test soils at greater depths, directly Disadvantage - Cost and disturbance caused by washing Why? - To have a continuous description of soil with depth, to retrieve samples via SPT and sampling tube, and to carry out SPT and vane shear tests

7. Disturbance caused by washing of a bore hole
Reportedly more than 12 inches (30 cm) in sands but only 3 inches (7.5 cm in clays)
Despite of the above, the practice only disregards 6 inches (15 cm) of SPT results in sands and in clays

8. Bore Hole Drilling Equipment: TOHO type for soil and rock drilling
Rotary type but can be converted to percussion type any time
Drilling: BS5030(1981)
Get soil samples via split spoon sampler
SPT(N) Test: BS1337(1975)
Normally, can also get 54 mm rock core (NX)

10. Soil Description vs. Soil Classification
The description of soils as drilling progresses is not a soil classification work (such as USCS) but mere layman’s description of the soils such as: Sand, Yellow Sand, Clay, Clay and Sand, Yellow Clay, Dense Sand, Loose Sand, Stiff Clay, etc.
The real soil classification is done when a sample has been subjected to lab tests and the results produced. Examples of classification names are MH, SM, etc., such as used in the USCS method.
A piezocone test also describes soils and appoint names but with another and different procedure than used in the USCS method.

11. SPT in a Borehole
Names of Test: Standard Penetration Test, SPT Data: Standard Penetration Test Number, SPT(N), Standard Penetration Resistance Hammer Weight: 63.5 kg (140 lb) Hammer Lift: 760 mm (30 in) Dimensions of Sampling Tube: 35 mm inside diameter, 50 mm outside diameter, 650 mm length Procedure: Number of blows per 75 mm advance is recorded for 6 consecutive advances starting at the bottom of a borehole. Numbers of blows of the last 4 advances (300 mm, 12 in, foot) are summed and is called SPT(N). Numbers of blows of the first two advances are discarded due to disturbance of the soil layer by washing and boring. Maximum number of blows per foot to record is 50.

13. How to get SPT(N) number
5.4 of MS1056
N30 is blows/30 cm
N60 is blows/30 cm assuming 60% hammer efficiency
Some demand blows/7.5 cm
Discard the blows of the first 15 cm (2x7.5)
Read blows for every 7.5 cm
So readings of 2, 3, 6, 7, 10, 19, 20 will give N30 = 42
Normally taken for every 1.5 m interval

14. SPT(N) versus f correlation for cohesion-less soils (Old JKR Document)
SPT(N) versus f correlation for cohesion-less soils (Coyle and Castello, 1981)
SPT(N) versus f correlation for cohesion-less soils (Old JKR Document)

15. SPT(N) versus f correlation for cohesion-less soils (McCarty, David F, 1998)10 20 30 40 50 60 32 35 38 42

17. SPT(N)
c, kPa 2 4 8 15 30 14 25 50
100
200

18. SPT in Sand
Angle of Friction
Description
0 – 4
0 – 28 degree
Very Loose
4 – 10
20 – 30
Loose
10 – 30
30 – 36
Medium
30 – 50
36 – 41
Dense
> 50
> 41
Very Dense

19. SPT in Clay
Cohesion (c), kPa
Description
< 2
0 – 14
Very Soft
2 – 4
14 – 25
Soft
4 – 8
25 – 50
Medium
8 – 15
50 – 100
Stiff
15 – 30
100 – 200
Very Stiff
> 30
> 200
Hard

20. N60 Equation (The corrected N due to depth)
Where:
N = Measured penetration number
A = Hammer Efficiency (Actual, in %)
B = Correction for BH diameter
C = Sampler Correction
D = Correction for Rod Length
Tables of correction factors available in book (e.g., Das B M, Fundamentals of Geotechnical Eng)
Why ? Because of 60% efficiency

21. Field Vane Shear
Names of Test: Field Vane Shear Apparatus to measure in-situ un-drained shear strength
Data: In-Situ Shear Strength
Maximum Depth: 30 m
Dimension of vane: 77 mm outer diameter
Procedure: Place shear vanes in cleared bore hole. Up to 30 m deep. Measure up to 100 kPa.

22. Field Vane Shear Apparatus

23. 3. Excavation and auger
Advantage - Able to retrieve representative samples and directly test soils at depths up to 6 m, cost effective Disadvantage - Depth limited by reach of bucket or length of auger Why? - To gain a quick information of soil to 6 m depth

24. Auger

25. 4. Piezocone Penetration (CPTU)
Advantage - Able to carry out tests at depths and unlike in boring, on relatively undisturbed soils, cost effective Disadvantage - No samples retrieved, cannot penetrate hard layer or rock like boring can Why? - To gain a relatively quick information of soil to 30 m depth

26. Piezocone Machine

27. Piezocone Penetration
Names of Test: Piezocone, CPTU, Cone Penetration Test with Pore Water Acquisition Data: Tip Resistance, Skin Friction, SPT(N) Equivalence, Soil Type, Pore Water Pressure, Dissipation of Pore Water Pressure Advance Rate: 2 cm/second Maximum Depth: 30 m Dimension of cone: 35 mm diameter, 10 cm square of cross sectional area Procedure: Cone advanced via rods to maximum depth of 30 m, data acquired automatically and continuously via computer

28. Piezocone - CPTU Observe how soil changes with depth
Observe how soil resistances (skin and end) change with depth
Observe how water pressure changes with depth
Cannot get samples
Cannot do field tests (other than those done by the cone)

29. Specific Cone Results Tip Resistance in MPa
Sleeve (skin) Friction in kPa
Pore Water Pressure (u) in kPa
These three values decide soil type according to table and N60 equivalent

30. Piezocone Probe

31. 5. Macintosh Probing
Advantage - Light, simple, fast, and cost effective Disadvantage - Cannot go very deep (10 m limit), less accurate interpretation Why? - To gain a relatively quick information of soil to 10 m depth, at the same time, cost effective

32. Macintosh Probing
Names of Tool: Macintosh Probe, Dynamic Probe, JKR Probe, Portable Penetrometer Data: Macintosh Probe Number, JKR Probe Number, Macintosh M-Value Hammer Weight: 5 kg (11 lb) Hammer Lift: 300 mm (12 in, foot) Dimensions of steel driving rod: 16 mm diameter, 120 cm length Dimension of coupling: 22 mm diameter x 52 mm length Dimensions of probes: JKR Probe (25.5 mm x 100 mm), Macintosh Probe (27.5 x 152 mm) Procedure: Number of blows per foot advance is recorded. Maximum blow per foot to record is 400

33. Operating Macintosh Probe

34. Portable probe
SI can be carried out manually
JKR probe versus (old) McIntosh probe
In Malaysia, we use JKR probe always
JKR gives same reading as McIntosh
JP (JKR probe); MP (McIntosh probe)
JP# =30 is equivalent to SPT(N) = 6 (medium) in clays
JP# =30 is equivalent to SPT(N) = 10 (loose-medium) in sands

35. 6. Field Density Test Sand replacement method
Main result is % of dry density achieved in the field as compared to dry density from lab compaction

36. 6. Rock and Fracture Mapping
Why?
- To gain information for determining stability against sliding and toppling for slopes
- To estimate cost of excavation for tunnels

37. Rock and Fracture Mapping involves:
Scan Line Survey
Collection of Joint Data
Stereographic Projection Method

38. 7. Geophysical Investigation
Resistivity, Seismic, and Microgravity
Advantage
- Fast and can cover large areas
Disadvantage
- Less accurate and has to be supplemented with boreholes
Why?
- To gain a relatively quick but rough information covering large area of site

39. tomography with borehole correlation
A resistivity survey result of an area over old landfill
Waste refuse + leachate contamination
Bedrock
A pseudo section of the subsurface imaging
tomography with borehole correlation

41. End of Lecture Session
Questions?

42. SI OF VARIOUS PURPOSES/PROJECTS
Aim
Grab Sampling
BH with SPT
BH with sampling tube
BH with vane shear
Excavate
Auger
CPTU
Mac-kintosh
Rock Mapping
General Assessment x
Geotechnical Assessment in an EIA
Slope Stability Design
Foundation Design
Embankment Design
Dam Design
Rock Slope Design
Rock Tunnel Design
Note: The required SI will depend on the actual project. This table is indication only, while geophysical methods are not included in the table.

43. Ready for Quiz?

44. The three Major Physical Properties of a Geotechnical Material required for design are:
Compressibility
Permeability
Shear strength
Which of the major physical properties is measured by the following tests? - SPT in Boreholes - Macintosh Probing - CPTU Penetration - Field Vane Shear - Plate Bearing - Consolidation test - Permeability test

45. Which soil property would you be concerned with?
If you come across any of the following cases:
- Settlement of a raft foundation
- Bearing failure of a pad foundation
- Failure of a pile foundation
- Water loss through a bund
- Failure of a slope
- Soft Ground
Which soil property would you be concerned with?
compressibility
permeability
shear strength

46. The design of which of the following structures require shear strength information?
Slope
Shallow foundation
Pile (deep) foundation
Embankment foundation
Ground improvement
Coast protection

47. How Deep should an SI (or assessment) go for the following purposes?
Embankment/Road Foundation
Pile Foundation
Settlement Investigation
Slope Assessment /Design
Landfill Assessment/Design
Rock Slope Assessment/Design
EIA/Geotechnical Assessment

48. EMBANKMENT/ROAD FOUNDATION

49. Stress Bulb underneath a road embankment

50. Stress reduction with depth

51. End