Download - Limas Final Workshop Earthquake[1]
-
8/2/2019 Limas Final Workshop Earthquake[1]
1/31
Seismic-induced liquefaction
around marine structures
-
8/2/2019 Limas Final Workshop Earthquake[1]
2/31
Two projects in LIMAS related to
seismic-induced liquefaction
Impact of earthquake-induced liquefactionon marine structures (with special
reference to the 1999 Kocaeli (Turkey)
earthquake) Mathematical modelling of pore-pressure
generation due to earthquakes and the
effect of the 1999 Kocaeli (Turkey)
earthquake on marine structures
-
8/2/2019 Limas Final Workshop Earthquake[1]
3/31
Colleagues working in these two
projects. Research Team
Niels-Erik Ottesen Hansen (LICengineering,
Denmark) Andrzej Zawicki (IBW, Poland)
Waldemar Swidzinski (IBW, Poland)
Wojciech Sulisz (IBW, Poland)
Jesper Damgaard (HR Wallingford, UK)
Turan Durgunoglu (ZETAS, Turkey) B. Mutlu Sumer (Technical University of
Denmark)
-
8/2/2019 Limas Final Workshop Earthquake[1]
4/31
Mechanism of liquefaction
During earthquake,
the groundexperiences strong,
cyclic accelerations,
a(t)
-
8/2/2019 Limas Final Workshop Earthquake[1]
5/31
Mechanism of liquefaction
During earthquake,
the groundexperiences strong,
cyclic accelerations,
a(t) Equation of motion for
a soil column implies
(in its simplest form):)a(
1)( tz
gt
t =
-
8/2/2019 Limas Final Workshop Earthquake[1]
6/31
Mechanism of liquefaction Cyclic acceleration translates
to cyclic shear stress in the
soil! This (shaking!) will rearrange
soil grains at the expense ofpore volume
This will, in turn, pressurize
the water in the pores, and The pore pressure, p, will
begin to build up
When p reaches theoverburden-pressure value,
the soil grains will becomeunbound and completely free,suspended in the water,and
The soil in this case begins toact like a liquid, theliquefaction process !
-
8/2/2019 Limas Final Workshop Earthquake[1]
7/31
Mechanism of liquefaction In the case of waves?
Panel (b) is a snap-shot Soil is compressed under
wave crest, expanded
under wave trough
This will generate a shear
deformation/shear stress
like
-
8/2/2019 Limas Final Workshop Earthquake[1]
8/31
Mechanism of liquefaction In the case of waves?
Panel (b) is a snap-shot Soil is compressed under
wave crest, expandedunder wave trough
This will generate a sheardeformation/shear stresslike this
The shear stress will vary
periodically as the wavecontinues
Soil will undergo cyclicshear stresses! Like in
the case of earthquakes!
-
8/2/2019 Limas Final Workshop Earthquake[1]
9/31
Period and intensity of shaking? Period? Panel shows
acceleration responsespectrum; Peak periodsvary over the range O(0.1s)-O(1 s)
Intensity? characterizedby PGA, not shown here,may vary from practically0 to O(0.6g)
In the Turkey earthquakethe max. recordedPGA=0.407g
-
8/2/2019 Limas Final Workshop Earthquake[1]
10/31
Mechanism of liquefaction The liquefaction process
is followed by a stagewhere
The suspended soilgrains in the liquefied soil
begin to settle in the waterwhile the pore pressuredissipates, thecompaction process
As a result, the surface ofthe soil will experiencelarge downwarddisplacement/settlement
-
8/2/2019 Limas Final Workshop Earthquake[1]
11/31
Images illustrating the impact of
liquefaction on marine structures
-
8/2/2019 Limas Final Workshop Earthquake[1]
12/31
Kocaeli (Turkey) Earthquake, 1999, Derince Port
Backfill liquefied and eventually settled; Quay wall damaged and crane damaged,along Berth 6
-
8/2/2019 Limas Final Workshop Earthquake[1]
13/31
Kocaeli (Turkey) Earthquake, 1999, Derince Port
3 years after!
-
8/2/2019 Limas Final Workshop Earthquake[1]
14/31
Kocaeli (Turkey) Earthquake, 1999, Derince Port
Settlement of backfill along Berth 4
-
8/2/2019 Limas Final Workshop Earthquake[1]
15/31
Nihonkai-chubu Earthquake, 1983, Akita Port
Settlement of backfill. Sheet-pile wall damaged; Damage due to pressures on
sheet-pile wall by liquefied backfill soil
-
8/2/2019 Limas Final Workshop Earthquake[1]
16/31
Kocaeli (Turkey) Earthquake, 1999, Izmit Marina
Liquefaction-induced settlement
-
8/2/2019 Limas Final Workshop Earthquake[1]
17/31
Kocaeli (Turkey) Earthquake, 1999
Vertical settlement of 48 cm was measured at this corner of the building. Adapazari.
Similar settlements of buildings at the water front in Bahceli-Seymen, East of Golcuk!
-
8/2/2019 Limas Final Workshop Earthquake[1]
18/31
Kocaeli (Turkey) Earthquake, 1999
Collapsed piers along Shell-Oil and Trans-Turk properties
-
8/2/2019 Limas Final Workshop Earthquake[1]
19/31
Highlights of the 1999 Turkey earthquake
Will highlight the liquefaction damage on marine
structures in the Turkey earthquake, as a casehistory!
Have given a full inventory of the damage in:
Sumer, Kaya & Hansen (2002): Impact ofliquefaction on coastal structures in the 1999
Kocaeli, Turkey Earthquake, Proceedings of the
12th ISOPE Conf., vol. II, pp. 504-511
-
8/2/2019 Limas Final Workshop Earthquake[1]
20/31
Highlights of the 1999 Turkey earthquake
Almost invariably, backfill areas behind
quay walls and sheet-piled structuresfailed due to liquefaction
Quay walls and sheet-piled structures
were displaced seaward, the
displacements being in the range from
O(10 cm) to O(1 m)
-
8/2/2019 Limas Final Workshop Earthquake[1]
21/31
Highlights of the 1999 Turkey earthquake
There are cases where the seabed settled
(It is not clear if these settlements are caused by liquefaction (andtherefore by the resulting consolidation) or by other processes suchas slope instability, surface rupture, etc, or a combination of thoseprocesses)
There are also cases where structuressettled (Again, it is not quite clear if these settlements (and collapses) are caused
by liquefaction or by other processes such as slope instability, surfacerupture, etc, or a combination of those processes)
Our calculations indicate, however, theseabed may have experienced liquefaction
-
8/2/2019 Limas Final Workshop Earthquake[1]
22/31
Highlights of the 1999 Turkey earthquake
Apartment buildings sank in the liquefied soil ofO(10-50 cm) at some water-front areas
Rubble-mound breakwaters largely survived theearthquake, except one case where
Some damage occurred to the rubble-mound
breakwater in Karamursel Eregli FishingHarbour
The damage was mostly in the form of flatteningof the cross-section, sliding of the slope, and
intrusion of the lower mound material into theloose sand
-
8/2/2019 Limas Final Workshop Earthquake[1]
23/31
Highlights of the 1999 Turkey earthquake
Two interesting observations!
-
8/2/2019 Limas Final Workshop Earthquake[1]
24/31
Highlights of the 1999 Turkey earthquake
95.000-ton capacity silos inDerince Port TMO facilities
survived the earthquake (This is despite the fact that alarge reclamation area settledin front of these silos)
Likewise, 510-ton shipyard
crane in UM Shipyard alsosurvived the earthquake
(Despite the large settlementof the area adjacent to thisstructure)
These structures survivedlargely because
They are supported on pilespenetrating into the stiff soil
-
8/2/2019 Limas Final Workshop Earthquake[1]
25/31
What are the questions adesign engineer faces?
-
8/2/2019 Limas Final Workshop Earthquake[1]
26/31
Questions a design engineer faces Given the design earthquake, and given the design of
the structure, the questions a design engineer faces are:
Can the soil (in the backfill, underneath, or the seabeditself supporting the structure,) be liquefied?
If the soil is liquefiable, how extensive will the damage tothe structure be?
Is this damage acceptable? (e.g., for quay walls: Is d/H < the specified value in thecode, like 1%, 5%, or 10%? e.g. PIANC, 2001, p. 34)
(If not, resort to remediation such as compaction;permeable stone / gravel columns, or drains;cementation / solidification)
With the remediation in place, what will the damage tothe structure (if any) be? Is it within the limit of damagecriteria?
-
8/2/2019 Limas Final Workshop Earthquake[1]
27/31
Guidelines? A substantial amount of knowledge has accumulated
over the past 40 years, addressing to these questions
This has led to excellent treatments on the generalsubject
Seismic Design (not necessarily liquefaction design)Guidelines for Marine Structures such as, among others:
CEN (European Committee for Standardization), 1994Eurocode 8: Design Provisions for EarthquakeResistance of Structures
ASCE, 1998, Seismic Guidelines for Ports
PIANC, 2001, Seismic Design Guidelines for PortStructures
All three publications included liquefaction designguidelines for marine structures
-
8/2/2019 Limas Final Workshop Earthquake[1]
28/31
LIMAS publication LIMAS has made an attempt to put
together a set of guidelines forliquefaction alone
This will be in the form of a paper, to be
submitted to the LIMAS Special Issue,
planned to be published in J. ASCE
Waterway, Port, Coastal and OceanEngineering
-
8/2/2019 Limas Final Workshop Earthquake[1]
29/31
LIMAS publication. List of contents Seismic-induced liquefaction. General
Review of the existing codes (related to marinestructures only)
Japanese experience of earthquake-induced liquefactiondamage on marine structures
Turkish experience of earthquake-induced liquefaction
damage on marine structures (with reference to 1999earthquake)
Lateral spreading
Soil improvement
Advanced mathematical modelling, and Tsunamis and their implications for marine structures
-
8/2/2019 Limas Final Workshop Earthquake[1]
30/31
AuthorsNiels-Erik Ottesen Hansen
Andrzej Zawicki
Jesper DamgaardB. Mutlu Sumer
We have also authors, invited from outside LIMAS:
A. Ansal (Bosporus University, Turkey)
Z. Sen (Kyushu University, Japan)
H. Yamazaki (Port and Airport Research Institute, Japan)
Y. Yuksel (Yildiz University, Turkey)
A. R. Gunbak (STFA, Turkey)
O. Cetin (METU, Turkey)
C. Synolakis (University of Southern California, USA)A.C. Yalciner (METU, Turkey)
T. Durgunoglu (ZETAS, Turkey)
-
8/2/2019 Limas Final Workshop Earthquake[1]
31/31
References1. Earthquake Spectra (2001). 1999 Kocaeli,
Turkey, Earthquake Reconnaissance Report,Supplement A to Earthquake Spectra, Volume16, Earthquake Engineering ResearchInstitute.
2. PIANC (2001). Seismic Design Guidelines forPort Structures. Balkema, the Netherlands.
3. Sumer, B.M., Kaya, A. & Hansen, N.-E.O.(2002): Impact of liquefaction on coastal
structures in the 1999 Kocaeli, TurkeyEarthquake, Proceedings of the 12th ISOPEConf., vol. II, pp. 504-511.