Nunziante Squeglia, Lo Presti Diego, Barbara Cosanti

UNIVERSITA’ DI PISADipartimento di Ingegneria dell’Energia, dei Sistemi del Territorio e delle Costruzioni

squeglia@ing.unipi.it

Re – evaluation of classification charts for CPTU in partially saturated loose silt mixtures

WORKSHOP ON PENETRATION TESTING 9 OCTOBER 2014

AUDITIORIUM OPERA PRIMAZIALE

MOTIVATIONS

SBT CLASSIFICATION CHARTS DO NOT CORRECTLY WORK IN CASE OF:

– PARTIALLY SATURATED SOILS

– LOOSE SILT MIXTURES

PARTIALLY SATURATED SOILS

EXAMPLE

BRONI (PV) SITE

Fine grained soil

POSSIBLE CORRECTION

EVALUATE SUCTION and CORRECT EFFECTIVE STRESS

ADOPTED MODEL

MK – KOVACS (Aubertin et al., 2003)

– granular soil f(D10, CU)

– fine soil f(LL)

EFFECT OF CORRECTION (Ic): - BRONI

ROBERTSON & CAMPANELLA (1986)ROBERTSON (1990)

EFFECT OF CORRECTION (SBT): BRONI

EFFECT OF CORRECTION (SBT): BRONI

LOOSE SILTY MIXTURES: Qc < 1 MPa

SERCHIO RIVER EMBANKMENTS

Ic FROM BOREHOLES VS. Ic FROM CPTU

Ic FROM BOREHOLES & CPTU

EFFECT OF CORRECTION

EFFECT OF CORRECTION

HOW TO DISTINGUISH LOOSE SILT MIXTURES FROM COMPRESSIBLE CLAYS ETC.

• COMPRESSIBLE CLAYS, PEATS, ETC. CAN HAVE qc < 1 MPa

• MAY FR GIVE USEFUL INDICATIONS?

• FRICTION RATIO < 4?

COMPRESSIBLE CLAYS: PISA EST

COMPRESSIBLE CLAYS: PISA WEST

COMPRESSIBLE CLAYS: PISA DISTRICT

COMPRESSIBLE CLAYS: LIVORNO DISTRICT

COMPRESSIBLE CLAYS: LUCCA DISTRICT

COMPRESSIBLE CLAYS: PRATO DISTRICT

EFFECT OF SLEEVE DIAMETER (HOSKIN ET AL., 2014)(NZ - SANDS)

ACKNOWLEDGEMENTS

• CPT DATA IN TUSCANY HAVE BEEN PROVIDED BY GEOSERVIZI (COSCO & SPADARO)

• CPT INTERPRETATION HAS BEEN CARRIED OUT BY SCARDIGLI & ZACCAGNINO (UNDERGRADUATER STUDENTS)

• CPT DATA FROM BRONI HAVE BEEN GIVEN BY PAGANI AND DR. MEISINA (UNIPV)

• CPT INTERPRETATION OF BRONI DATA HAS BEEN CARRIED OUT BY ROSIGNOLI (GRADUATE STUDENT)