INCORPORATION OF EARTHQUAKE SOURCE,

PROPAGATION PATH AND SITE UNCERTAINTIES INTO

ASSESSMENT OF LIQUEFACTION POTENTIAL

Bob DarraghNick GregorWalt Silva

Pacific Engineering and AnalysisEl Cerrito, CA

OBJECTIVE

EVALUATE QUALITATIVELY THREE METHODS

FOR LIQUEFACTION (TRIGGERING)

• ANDRUS AND STOKOE (2000): Vs

• KAYEN AND MITCHELL (1997): ARIAS INTENSITY, SPT

• SEED AND OTHERS (2001): CSR, SPT

METHODEQUIVALENT LINEAR SITE RESPONSE

BLWN: RVT APPROACH

FINITE SOURCE

PARAMETRIC VARIATIONS IN MATERIAL PROPERTIES

STATISTICALLY RIGOROUS ASSESSMENT OF PARAMETERS THAT

CONTROL CYCLIC DEMANDS

SITE SPECIFIC ANALYSES12 CASE STUDIES FROM 6 EARTHQUAKES

LOMA PRIETA: 5 SITES

3 EARTHQUAKES: WILDLIFE LIQUEFACTION

SUPERSTION HILLS (B): KORNBLOOM ROAD

NORTHRIDGE: 2 SITES

KOCAELI: ADAPARAZI

COMPARE FACTORS OF SAFETY ANDPROBABILITY OF LIQUEFACTION WITHVISUAL MANIFESTATIONS OF LIQUEFACTION

5 SITES LIQUEFIED (ALAMEDA NAVAL AIR STATION)

7 SITES DID NOT LIQUEFY (EMERYVILLE PACIFIC PARK PLAZA)

REGIONAL ANALYSES

1995 KOBE EARTHQUAKE: 654 SITES

FINITE RUPTURE SIMULATIONS

RUPTURE DIRECTIVITY

DURATION

COMPARE FACTORS OF SAFETY ANDPROBABILITY OF LIQUEFACTIONWITH AREAL SURVEYS OF SAND BOILS

APPROPRIATE FOR LIQUEFACTION MAPPING STUDIES

Model Bias estimates computed over the 25 recording sites (fault distance range of 1 to 158 km).

Median estimates of peak acceleration values at the rock, hard, soft, and fill areas of Kobe, Nishinomiya, and Osaka.

0 2 4 6 8 10 Kilometers

Arias Intensity (cm/sec)

<50

50 - 100

100 - 150

150 - 200

>200

Median estimates of Arias Intensity for the rock, hard, soft, and fill areas of Kobe, Nishinomiya, and Osaka.

Zones of surface expression of ground failure (from Iwasaki, 1997).

Median estimates of the factor of safety using the Andrus and Stokoe (2000) approach at the rock, hard, soft, and fill areas of Kobe, Nishinomiya, and Osaka.

Median estimates of the factor of safety using the Kayen and Mitchell (1997) approach at the rock, hard, soft, and fill areas of Kobe, Nishinomiya, and Osaka.

Median estimates of the factor of safety using the Seed et al. (2001) approach at the rock, hard, soft, and fill areas of Kobe, Nishinomiya, and Osaka.

CONCLUSIONSALL 3 APPROACHES REPRESENT TOOLS TO QUANTIFY LIQUEFACTION

HAZARD AT REGIONAL SCALES

THE Vs BASED APPROACH WAS MORE ACCURATE

THE SPT APPROACHES WORKED RATHER WELL, GENERALLY BEINGCONSERVATIVE, CONSIDERING SPT DATA WERE NOT USEDDIRECTLY (3 CORRELATION MODELS OF Vs AND SPT)

REPORT

USGS AWARD No. 02HQGR0022

INCORPORATION OF EARTHQUAKE SOURCE, PROPAGATION PATH,AND SITE UNCERTAINTIES INTO ASSESSMENT OF LIQUEFACTIONPOTENTIAL; PHASE 1, VALIDATION

Silva, Darragh and Gregor (2005), 262 pp