CPT data

No.

Interpreted

Parameter

Description

Equation

Refs

0

(ft)

Layer bottom depth

Measured

1

(ft)

Layer middle depth

2

Average recorded tip value

3

Average recorded sleeve friction 

4

Average recorded power water pressure 

Non-normalized

5

Average corrected tip value 

Robertson (1990) 

6

Friction ratio

Robertson (1990)

7

SBT

Non-normalized Soil Behavior Type

Seechart

Robertson (1990)

8

(pcf)

Unit weight

See Table 1

* Overconsolidated or cemented

Lunne et al (1997)

For Saturated Soil Materials:

       (kN/m3, m/s, m)

       (kN/m3, m/s, m)

Maybe et al. (2001)

Maybe et al. (2009)

9

Total overburden pressure

10

Effective overburden pressure

11

Normalized core resistance

, (if , )

Robertson (1990)

12

Normalized core parameter

,

       ,

,

        (in kPa),  

Robertson (2008)

13

Normalized friction ratio

Robertson (1990)

14

Normalized soil behavior type

Seechart

Robertson (1990)

15

Soil Behavior Type index

,

,

Robertson & Wride (1998)

16

Normalized

()

()

Robertson & Wride (1998)

       ,

Idriss & Boulanger (2008)

17

CPT grain characteristic correction factor

:

,

       other criteria

Robertson & Wride (1998)

18

Clean sand equivalent

Robertson & Wride (1998)

Idriss & Boulanger (2008)

19

Soil behavior based on

* Overconsolidated or cemented

Robertson (1990)Robertson & Wride (1998)

20

Pore pressure ratio

Robertson (1990)

21

Soil behavior based on

Robertson (1990)

22

Fines content (%)

,

       ,

,

and ,

Robertson & Wride (1998)

Cetin & Ozan

23

Normalized net cone tip resistance

and

Cetin & Ozan (2009)

24

c

Parameter c for

,

Cetin & Ozan (2009)

25

R

Parameter R for calculating c

Cetin & Ozan (2009)

26

Shear wave velocity parameter

in (m/s)2

Robertson (2008)

27

Shear wave velocity

in (m/s)

Robertson (2008)

28

Shear wave velocity

 in (ft/s)

29

Initial shear modulus

in kPa (ρ in t/m3)

Robertson (2008)

30

Initial shear modulus

in (psf)

31

Young’s modulus

       degree of loading 0.2 to 0.3

       with known

Robertson (2008)

32

M

Constrained modulus

When use:

               when

               when

When use:

Robertson (2008)

33

Preconsolidation stress

For clay,

For sand,

Kulhawy & Maybe (1990)

34

OCR

Over consolidation ratio

For clay, :

, with as an average value. 

Robertson (2008)

       Other OCRs

, (m/s, tsf)

Maybe (2007)

For sand,

Maybe (2007)

       Other OCRs

Maybe (2007)

35

Soil Sensitivity

Robertson (2008)

36

Undrained shear strength

, with 14 as an average 

Robertson (2008)

37

Undrained shear strength ratio

Robertson (2008)

38

Friction angle

Sand:

        or

        or

Robertson & Campanella (1983a)

Kulhawy & Mayne (1990)

Robertson (2008)

Clay:

Mayne et al. (2001)

Yi (2009)

39

Effective cohesive strength

For clay,

For sand,

Mayne (2007)

40

Compression coefficient

When use:

        in decimal

When use:

        in decimal

For sand,

Robertson (2008)

41

Rebound coefficient

For clay,

For sand,

Cetin & Ozan

42

Fines Content

Cetin & Ozan (2009)

43

Liquid limit

Cetin & Ozan (2009)

44

Plasticity index

Cetin & Ozan (2009)

45

Coefficient of lateral earth pressure at rest

Fine grained soils:

Kulhawy & Maybe (1990)

Coarse grained soils:

Maybe & Kulhawy(1982)

Mayne (2007)

46

Relative density

, (,)

, ()

,  ()

Zhang et al (2004)Idriss & Boulanger (2004)

Jamiolkowski et al (2001)

Yi (2009)

SPT

47

from SBT

* Overconsolidated or cemented

Lunne et al (1997)

48

from

Lunne et al (1997)

Jefferies & Davies (1993)

49

from

Idriss & Boulanger (2004)

50

Overburden pressure correction

<1.7

Liao & Whitman (1986a)

       ,

Idriss & Boulanger (2008)

51

Normalized clean sand based on Lunne et al (1997)

Youd et al (2001)

52

Normalized clean sand based on

Youd et al (2001)

53

Normalized clean sand based on Idriss & Boulanger (2004)

Idriss & Boulanger (2004)

54

Normalized clean sand based on  modified from Lunne et al (1997)

55

Stress reduction coefficient

Liao & Whitman:

       , for

       , for

       , for

       , for

Liao & Whitman (1986)

NCEER/NSF (2001)

Blake:

Blake (1996)

Idriss:

       , z in ft

Idriss (1999)

56

MSF

Magnitude scaling factor

NCEER Workshop lower bound (Idriss)

NCEER Workshop up bound (Andrus & Stokoe 1997)

Yi (revised)

Yi (revised)

Sand-like soils

Clay-like soils

Boulanger & Idriss (2004b)

Boulanger & Idriss (2004b)

57

Correction for overburden pressure

,

Hynes & Olsen (1999)

       , or

Idriss & Boulanger (2004)

58

Correction for initial (static) shear stress

Idriss & Boulanger (2004)

59

Cyclic stress ratio

Seed & Idriss (1971)

60

Cyclic resistance at M=7.5

if , 

       If ,

       If ,

Robertson & Wride (1998)

Idriss & Boulanger (2008)

if , 

Boulanger & Idriss (2004b)

if

       n/a (clay)

61

FS

Factor of safety for liquefaction

62

Average cyclic shear stress

63

Average stress

Shear strain

64

or

Shear strain

(based)

Dry sand:

       ,

Pradel (1998) (for dry sand)

Saturated sand:

Zhang et al (2004)

, if

                               if

, if

Idriss & Boulanger (2008)

65

Shear modulus ratio

66

Volumetric strain

Dry sand:

Pradel (1998) (for dry sand)

       (old)

(Yi, )

(Idriss, )

(Zhang, )

(Jamiolkowski, )

Yi (2009)

Saturated sand:

Zhang et al (2002)

Idriss & Boulanger (2008)

67

Seismic settlement increment

Dry sand:

Pradel (1998) (for dry sand)

Saturated sand:

Zhang et al (2002)

68

Cumulated seismic settlement (in)

   (based)

69

Lateral displacement increment

Saturated sand:

Zhang et al (2004)

70

Cumulated lateral displacement

and :

Gently sloping ground without a free face:

       ,

Level ground with a free face:

       ,

Gently sloping ground with a free face:

Zhang et al (2004)

71

or

Shear strain

(→)

Dry sand:

       ,

72

Shear modulus ratio

73

Dry sand:

74

Seismic settlement increment

Dry sand:

Saturated sand:

75

Cumulated seismic settlement (in)

   (→, original Pradel)

76

Fines content

(recommended)

Yi (2009)