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| Titel |
Liquefaction assessment based on combined use of CPT and shear wave velocity measurements |
| VerfasserIn |
Zoltán Bán, András Mahler, Erzsébet Győri |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144007
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| Publikation (Nr.) |
 EGU/EGU2017-7783.pdf |
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| Zusammenfassung |
| Soil liquefaction is one of the most devastating secondary effects of earthquakes and can
cause significant damage in built infrastructure. For this reason liquefaction hazard shall be
considered in all regions where moderate-to-high seismic activity encounters with saturated,
loose, granular soil deposits. Several approaches exist to take into account this hazard, from
which the in-situ test based empirical methods are the most commonly used in
practice.
These methods are generally based on the results of CPT, SPT or shear wave velocity
measurements. In more complex or high risk projects CPT and VS measurement are often
performed at the same location commonly in the form of seismic CPT. Furthermore, VS
profile determined by surface wave methods can also supplement the standard CPT
measurement. However, combined use of both in-situ indices in one single empirical method
is limited.
For this reason, the goal of this research was to develop such an empirical method within
the framework of simplified empirical procedures where the results of CPT and VS
measurements are used in parallel and can supplement each other. The combination of two
in-situ indices, a small strain property measurement with a large strain measurement, can
reduce uncertainty of empirical methods.
In the first step by careful reviewing of the already existing liquefaction case history
databases, sites were selected where the records of both CPT and VS measurement are
available. After implementing the necessary corrections on the gathered 98 case histories with
respect to fines content, overburden pressure and magnitude, a logistic regression was
performed to obtain the probability contours of liquefaction occurrence. Logistic regression is
often used to explore the relationship between a binary response and a set of explanatory
variables. The occurrence or absence of liquefaction can be considered as binary outcome and
the equivalent clean sand value of normalized overburden corrected cone tip resistance
(qc1Ncs), the overburden corrected shear wave velocity (V S1), and the magnitude and
effective stress corrected cyclic stress ratio (CSRM=7.5,σv′=1atm) were considered as input
variables.
In this case the graphical representation of the cyclic resistance ratio curve for a given
probability has been replaced by a surface that separates the liquefaction and non-liquefaction
cases. |
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