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Practice and development of the piezocone penetration test (CPTu) in geotechnical
engineering of China
La pratique et le développement de
l'essai de
pénétration au piézocône (CPTu) en Chine
Liu S., Cai G., Du Y.
Institute of Geotechnical Engineering,Southeast University, Nanjing 210096, China
Puppala A.J.
Department of Civil Engineering, The University of Texas at Arlington, Arlington, Texas
ABSTRACT: The cone penetration test (CPT) technique is widely used in field site investigation due to its fast, repeatable, and cost-
effective advantages. It can provide near-continuous information of soil properties and has a strong theoretical background. In this
paper, the history and current development status of CPT, particular the cone penetration test with pore pressure measurement (CPTu)
in China practice is systematically introduced. The relationship between international standardized CPTu and China CPT is proposed
based on a great number of soils. The paper then presents the review and comparison of the soil characterization methods based on
CPTu tests results in China, including stress history, deformation, consolidation and permeability characteristics.
RÉSUMÉ: L’essai de pénétration au cône (CPT) est largement utilisé dans les enquêtes de terrain pour ses avantages rapides,
reproductibles et rentables. Il peut fournir des informations quasi continues des propriétés du sol et il a une solide théorie. Dans cet
article, l’histoire et l’état et développement du CPT, notamment l’essai de pénétration au piézocône (CPTu) qui peut mesurer la
pression d’eau interstitielle est systématiquement introduit en Chine. La relation entre les résultats normalisée interationale CPTu et
des CPTs en Chine est proposée selon beaucoup des données. Par la suite, le document présente l’examen et la comparaison des
méthodes de caractérisation des sols par les résultats des CPTUs en Chine, y compris l’historique des contraintes, des déformations,
des caractéristiques de perméabilité et de consolidation.
KEYWORDS: Site investigation, CPT, CPTu, Engineering Characterization
1INTRODUCTION
The cone penetration test (CPT) has been used for decades to
investigate the properties of soil in situ. Essentially, the test
consists of pushing a penetrometer with a standard geometry
(cylindrical with a diameter of 35.7 mm and a conical point
with an apex angle of 60
o
) into the soil at a rate of 20 mm/s,
while measuring a number of parameters. The cone penetration
test (CPT) is widely used in-situ testing method, especially in
soft soil exploration. As a new kind of in-situ test technique, the
piezocone penetration test (CPTu) has been attracting wide
attention and widely used in the western developed country. It
has been increasingly used because of its important advantages,
such as simplicity, speed and continuous profiling. The
piezocone, which provides near-continuous measurements of tip
resistance, sleeve friction, and pore water pressure induced
during the penetration, appears to be a powerful tool for
determining the stress history of soft clay deposits.
The mechanical CPT like “Dutch” cone was developed by
foreign engineers in Shanghai in the early 1930’s (Liu and Wu,
2004). In 1954, the Holland mechanical CPT was first
introduced into China. In 1964, the first electric single bridge
CPT was independently produced in China with only one
measurable parameter (e.g., total specific penetration
resistance). Later, the double bridge CPT was developed to
measure the tip resistance and sleeve friction independently in
the 1970’s, which is currently used in Chinese standards. The
Holland CPTu was introduced into China in the early 1990’s by
Nanjing Hydraulic Research Institute, but its follow-up
development is very slow. The multifunctional CPTu was
introduced into China in 2005 by Southeast University
researchers. In the following years, the related theory analysis
and application practice of CPTu in China have been developed
rapidly. In this paper, the relationship between international
standardized CPTu and China CPT is proposed based on a great
number of soils. The paper then presents the review and
comparison of the soil characterization methods based on CPTu
tests results in China, including determination of stress history,
deformation, consolidation and permeability characteristics.
2 COMPARISON BETWEEN INTERNATIONAL
STANDARDIZED CPTU AND CHINA CPT
Due to the inner geometry of a cone penetrometer, the ambient
pore pressure will act on the shoulder area behind the cone.
Therefore, the measured cone resistance should be corrected by
the unequal area effect for the data presentation and
interpretation. In literature works, most of the correlations were
developed based on CPT with cone cross area of 10 cm
2
as per
international standardized CPT and CPTu tests. However, in
China, both 15 cm
2
and 20 cm
2
CPT devices are frequently
used. Therefore, the internationalization of Chinese CPT is
inevitable (Liu and Wu, 2004).
When different sizes of CPT and CPTU are employed, the
question of scale effects inevitably arises. For piezocones
ranging in area from 5 to 15 cm
2
, the usual assumption, based
on experience summarized by Lunne et al. (1997), is that scale
effects are negligible in soil layers of sufficient thickness
relative to the cone diameter: that is, quantities such as the cone
resistance and excess pore pressure do not depend on the size of
the piezocone. Powell and Lunne (2005) compared the results
using the 10 cm
2
and 15 cm
2
piezocones in UK clays. The
comparison of various cone sizes and configurations between
China CPT and international standard CPTu device at 28 field
testing sites is presented. To avoid the variability, all the tests
were performed by the same operators. The elevations of the
