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Published By Lankelma

Lankelma is the foremost contractor for onshore in-situ soil testing in the UK. An acknowledged specialist in CPT, Lankelma also offers a worldwide consultancy and training service.

A.P. van den Berg develops, designs and manufactures geotechnical and environmental soil investigation equipment for onshore and offshore applications. Specialists in CPT systems and equipment.


Gardline Geosciences offers worldwide marine geotechnics, in-house consutancy and services with marine investigations ranging from nearshore to full ocean depth (down to 3000m).

About the Author

Hans Brouwer studied civil engineering at Delft University in The Netherlands. He has worked as a part-time lecturer at Amsterdam Polytechnic and was senior partner in a structural engineering consultancy. He has written a standard textbook in Dutch about the design of building foundations. He now lives in England where he writes technical textbooks in English, hopefully to reach a bigger readership.

Chapter 1


Symbols, abbreviations and engineering units



Symbols    (abbreviations  engineering units)

Only the symbols which are not directly explained in the guide are given here

 a area ratio of the cone = An/Ac
 Acprojected area of the cone
 Ancross-sectional area of load cell or shaft
 Bqpore pressure ratio = (u2-u0)/(qtvo)
 ccoefficient of consolidation
 chhorizontal coefficient of consolidation
 cvvertical coefficient of consolidation
 Cu undrained shear strength
 D diameter
 E Young's modulus
 fs unit sleeve friction resistance
 ft sleeve friction corrected for pore pressure effects
 Fr normalised friction ration = fs/(qtvo)
 G shear modulus
 Hlayer thickness
 k coefficient of permeability
 mv coefficient of volume change
 N number of blows in the SPT
 qc measured cone resistance
 qca equivalent average cone reistance
 qn net cone resistance = qt-σvo
 qt corrected cone resistance = qc + (1-a).u2
 qe effective cone resistance = (qc-a.u2) = (qt-u2)
 Qc normalised cone resistance = (qcvo)/σ'vo
 Qtnormalised cone resistance = (qtvo)/σ'vo
 Rffriction ratio = (fs/(qc).100%
 t time
 t50 time for 50% dissipation of excess porewater pressure
 uporewater pressure
 u0in-situ pore pressure
 u1 pore pressure measured on the cone
 u2 pore pressure measured behind the cone
 u3pore pressure measured behind friction sleeve
 uipore pressure at time t = 0
 ut pore pressure at time = t
 Δu excess porewater pressure = (u-u0)
 U normalised excess pore pressure
 z depth
 σv total vertical stress
 σvo total overburden stress
 σ'veffective vertical stress
 σ'vo effective overburden stress
 Φ' effective friction angle

Abbreviations    (symbols   engineering units)

BGLbelow ground level
BSP British Standard pipes
CAUanisotropic consolidated undrained tiraxial test
CFA continuous flight augur
CIU consolidated isotropic undrained
CPT cone penetration test
CPTU CPT with pore pressure measurement (piezocone test)
FSK frequency shifting key
GPR ground probing radar
HDPE high density polyethylene
ICRCL Inter Departmental Committee on Redevelopment of
Contaminated Land
ISSMGE International Society of Soil Mechanics and Geotechnical Engineering
IRTP international reference test procedure
MC moisture content
NAPL non-aqueous phase liquid
LNAPL light non-aqueous phase liquid
NCnormally consolidated
OC over-consolidated
OCR over-consolidated ration
PAH polycrylic aromatic hydrocarbon
PC personal computer
PI particle index
PSD particle size distribution
PVC polyvinyl chloride
pH concentration of hydrogen ions (acidity/alkalinity factor)
SO4 total sulphate
SPT standard penetration test
UU unconsolidated undrained
UV ultraviolet

     Engineering units
    (symbols  abbreviations )
 micro (μM) 10-6
 milli (m) 10-3
 kilo (k) 10+3
 mega (M)10+6
 SI base units 
 lengthmetre (m)
 area square metre (m2)
 force newton (N)
 pressure or stress pascal (Pa) (=N/m2)
 Multiple units  
 length millimetre (mm)
  kilometre (km)
 area square millimetre (mm2)
  square kilometre (km 2)
 forcekilonewton (kN)
 pressure or stress kilonewton per square metre (kPa)
  Meganewton per square metre (MPa)
 Conversion factors 
 force1 kg = 10 N
  1 ton = 10 kN
 pressure or stress 1kg/cm2 = 100 kPa = 100 kN/m2
  1 bar = 100 kPa = 100 kN/m2
  1 ton/m2 = 10 kPa = 10 kN/m2
  (ie 1m of water = 10kPa)
 Derived values for CPTU 
 excess pore pressure Δu - u2-u0
 corrected cone resistance qt = qc = (1 - a).u2
 net cone resistance qn = qt - σvo
 friction ratioRf = (fs/qt) x 100%
 pore pressure ration Bq = Δu/qn
 normalised excess pore pressure U = (ut -Uo)/(ui-uo) where ut is the
pore pressure at time t in a dissipation test
and ui is the pore pressure at the start of
the dissipation test


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