| Due to its simplicity, the cone penetration test (CPT) is a popular in-
situtesting method. CPT is especially desirable in characterizing sand where it is
difficult to obtain undisturbed samples. Because of the large strain which occurs
during a cone penetration, theoretical analysis of CPT results has been difficult
and,hence, limited. Accordingly, interpretation of CPT data is mostly based on
empirical correlations. Some of the empirical correlations are based on CPT in the
calibration chambers. An important drawback of interpreting CPT in a calibration
chamber is its boundary effects. Correction factors have been proposed to account
for these boundary effects. However, the validity of the use of correction factors
and the mechanisms of boundary effects have not been independently verified.
The authors have developed an axisymmetric field simulator in which CPT
calibration tests can be conducted under substantially reduced boundary effects. A
series of CPT calibration tests has been performed in the new simulator system to
correlate the cone tip resistance (qc) with the stress state. Results show that the
correlation of qc and the initial effective mean normal stress (prior to cone
penetration) is clearer than the other components of the initial stress state.
However, under the same initial effective mean normal stress, qc has a consistent
localized relationship with the initial horizontal stress. qc is affected by the
horizontal stress near the cone tip, where there exists an obvious correlation
between them. This paper introduces chamber calibration tests of CPT, describes
this new field simulator system, presents available CPT data obtained using the
new simulator and discusses the stress state affected qc values.