Microzonation for earthquake hazards: Yeniehir settlement, Bursa, Turkey


Topal, T.; Doyuran, V.; Karahanoğlu; N.; Toprak, V.; Süzen, M.L.; Yeşilnacar, E.

Engineering Geology 70(1-2): 93-108

2003


Available
online
at
www.sciencedirect.com
SCIENCE
d
DIRECT.
ENGINEERING
GEOLOGY
ELSEVIER
Engineering
Geology
70
(2003)
93-108
www.elsevier.com/locate/enggeo
Microzonation
for
earthquake hazards:
Yeni§ehir
settlement,
Bursa,
Turkey
T.
Topal
*
,
V.
Doyuran,
N.
Karahanoglu,
V.
Toprak,
M.L.
Siizen,
E.
Ye§ilnacar
Department
of
Geological
Engineering,
Middle
East
Technical
University,
Ankara
06531,
Turkey
Received
12
June
2002;
accepted
10
March
2003
Abstract
Detailed
geological,
hydrogeological
and
geotechnical
studies
were
performed
for
the
assessment
of
the
foundation
conditions
of
the
present
and
future
settlement
areas
of
Yeni§ehir.
Yeni§ehir
is
located
50
km
east
of
Bursa,
Turkey,
within
an
east—west
trending
elliptical
sedimentary
basin.
The
present
and
future
development
areas
of
Yeni§ehir
cover
10
km
2
.
The
topography
of
the
settled
area
is
quite
smooth
and
the
slopes
are
generally
less
than
10°.
Yeni§ehir
is
located
within
a
First-Degree
Earthquake
Zone
of
Turkey
according
to
the
seismic
design
code.
The
seismicity
of
the
town
is
mainly
controlled
by
the
Geyve-tznik
and
Bursa
fault
zones.
The
study
also
involves
trial
pitting,
drilling,
in
situ
testing
and
laboratory
testing.
Borehole
logs,
index
properties
of
soils,
standard
penetration
test
results
and
groundwater
level
measurements
were
used
for
activity
and
liquefaction
assessments
of
the
foundation
material.
Based
on
the
evaluation
of
the
data,
two
geotechnical
zones
were
distinguished.
The
northern
part
of
the
area
is
characterized
by
cohesive
soils
of
high
expansion
behaviour
and
the
southern
part
by
alternation
of
cohesive
and
non-cohesive
soils
showing
high
liquefaction
potential.
CO
2003
Elsevier
Science
B.V.
All
rights
reserved.
Keywords:
Geotechnical
investigation;
Liquefaction;
Microzonation;
Urban
geology;
Yeni§ehir
1.
Introduction
Urban
planning
becomes
an
important
issue
where
urban
areas
expand
as
a
result
of
an
increase
in
urban
population.
The
balance
between
human
occupation
and
the
natural
environment
becomes
severely
disrup-
ted
due
to
urbanization
(De
Mulder,
1996).
The
objec-
tive
of
urban
planning
is
to
reduce
the
number
of
conflicts
and
adverse
environmental
impacts
so
that
the
quality
of
life
and
the
general
welfare
of
the
*
Corresponding
author.
Fax:
+90-312-210-1263.
E
-
mail
address:
topal@metu.edu.tr
(T.
Topal).
community
are
improved
(Bell,
1998;
Bell
et
al.,
1987).
Such
planning
requires
a
multidisciplinary
approach
for
various
human
needs
(De
Mulder,
1996).
However,
in urban planning,
geological
and
geotechnical
data
are
becoming
increasingly
important
for
the
recognition,
control
and
prevention
of
geo-
logical
hazards
(Bell
et
al.,
1987;
Legget,
1987;
Hake,
1987;
Rau,
1994;
Dai
et
al.,
1994,
2001;
Van
Rooy
and
Stiff,
2001).
Yeniwhir
is
a
settlement
area
with
a
population
of
around
26,000.
It
is
situated
50
km
east
of
Bursa,
Turkey
(Fig.
1).
The
present
and
planned
future
settle-
ment
areas
of
Yeni
ehir
cover
10
km
2
.
The
rate
of
population
growth
is
about
2.5%
per
year
both
in
the
0013-7952/03/$
-
see
front
matter
©
2003
Elsevier
Science
B.V.
All
rights
reserved.
doi:10.1016/S0013-7952(03)00085-1
Z's
IZMIT
Mick
w
Iznik
Black
Sea
NAFZ
co
URKEY
o
200
Medit
rranean
Sea
km
Demirtas
BURSA
tudy
Area
enisehir
Yenicekoy
Inegal
Orhaneli
BILECIK
Keles
25
50
(km)
94
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
Fig.
1.
Location
map
of
the
study
area.
NAFZ:
North
Anatolian
Fault
Zone,
EAFZ:
East
Anatolian
Fault
Zone.
region
and
in
Yenisehir
(SIS,
2002).
Almost
half
of
the
settlement
area
in
Yeni*ehir
is
currently
urbanized.
Yeniwhir
is
located
within
a
First-Degree
Earthquake
Zone
(highest
hazard)
of
Turkey
according
to
the
seismic
design
code
(GDDA,
1996).
The
seismicity
of
the
area
and
its
vicinity
is
mainly
controlled
by
the
southwestern
strands
of
the
North
Anatolian
Fault
Zone
(NAFZ).
The
August
17,
1999
Izmit
earthquake
(M
s
=
7.4),
which
produced
extensive
structural
dam-
age
and
the
loss
of
almost
18,000
lives
in
the
Marmara
region,
was
also
felt
rather
strongly
by
the
residents
of
Yen*hir.
The
earthquake
produced
no
serious
struc-
tural
damage
but
caused
significant
ground
vibrations
and
created
panic
among
the
people.
The
town
received
no
migrants
after
the
August
17,
1999
Izmit
earthquake.
Following
the
August
17,
1999
event,
the
General
Directorate
of
Disaster
Affairs
of
the
Ministry
of
Reconstruction
and
Resettlement
of
Turkey
declared
the
commencement
of
geological
and
geotechnical
review
studies
for
all
municipalities
affected.
In
this
study,
geological,
hydrogeological
and
geo-
technical
investigations
were
performed
for
the
assess-
ment
of
the
foundation
conditions
of
the
present
and
future
settlement
areas
of
Yeniwhir.
This
paper
de-
scribes
the
stages
and
details
of
the
investigation
of
the
urban
geology
aiming
at
the
preparation
of
a
micro-
zonation
map
of
Yenisehir.
2.
Morphological
setting
Yeniwhir
is
located
within
a
small
elliptical
sedi-
mentary
basin
extending
in
the
east—west
direction
(Fig.
2).
Kocasu
stream
is
the
main
stream
of
the
basin.
It
flows
from
southwest
to
northeast
and
has
a
low
discharge
rate.
An
irrigation
dam
across
the
stream
is
currently
under
construction.
The
settlement
area
is
bounded
by
ridges
both
to
the
north
and
to
the
south.
The
maximum
elevation
(350
m)
corresponds
to
the
northern
margin
of
Yeni*ehir.
The
elevation
gradually
decreases
to
220
m
towards
south.
The
study
area
has
gentle
slope:
the
average
slope
of
the
study
area
is
generally
less
than
5
°
and
it
locally
reaches
up
to
10°
in
the
north
(Fig.
3).
The
small
catchment
area
of
the
stream,
historical
records
from
the
municipality,
low
discharge
rate
of
the
stream
and
field
studies
suggest
that
no
flood
hazard
is
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
95
-4
LEGEND
Yenisehir
Municipal
Boundary
Road
0
250
500
(metres)
1
4
'
art
Fig.
2.
Morphological
map
of
Yenisehir
and
its
vicinity.
expected
in
the
study
area.
Completion
of
the
irrigation
dam
will
further
minimize
any
flood
hazard.
In
the
study
area,
no
ancient
and/or
recent
slope
movements
have
been
observed.
The
presence
of
gentle
slopes
throughout
the
settlement
area
precludes
any
kind
of
slope
movements,
except
for
liquefaction-induced
lat-
eral
spreading.
3.
Seismotectonics
The
seismicity
of
Yeniwhir
and
its
vicinity
is
mainly
controlled
by
Geyve-Iznik
Fault
Zone
in
the
north,
Bursa
Fault
in
the
west
and
Inonil-Eskisehir
Fault
Zone
in
the
south
(Doyuran
et
al.,
2000)
(Fig.
4).
Epicenter
data
for
historical
earthquakes
used
in
Fig.
4
are
taken
from
BOUN-KOERI
(2002).
3.1.
Geyve-Iznik
Fault
Zone
The
Geyve-Iznik
Fault
Zone
corresponds
to
the
southern
branch
of
the
NAFZ,
a
major
right-lateral
strike-slip
fault
that
extends
all
the
way
from
the
North
Aegean
Sea
towards
East
Anatolia
over
a
distance
of
approximately
1200
km
with
well-devel-
oped
surface
expression
(Erdik
et
al.,
1985).
The
zone
includes
parallel
and
subparallel
active
right-
lateral
strike-slip
faults.
The
Geyve-Iznik
Fault
Zone
is
located
25
km
north
of
Yeniwhir.
It
is
the
nearest
active
fault
zone
to
the
settlement
area.
The
Geyve-
Iznik
Fault
Zone
has
a
potential
to
generate
an
earthquake
of
magnitude
7.5
and
a
maximum
hori-
zontal
ground
acceleration
of
0.5-0.6
g
at
the
epicentral
area
(Erdik
et
al.,
1985;
Gillkan
et
al.,
1993).
USK-204A
USK-204
0
0
SK-385
SK-386
0
SK-384
O
0
0 0
USK-205A
USK-205
0
usK-205B
SK-383
96
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
K-6
N
MC-35
A
E
SK-
MC
34
USK-198
SK-11
0
250
500
750
1000
II
1
(m)
USK-1
SK-374
MQ-36
0
USK-196
MQ-18
0
USK-195
0
SK-373
0
0
SK-372
SK
371
°
W-8
MQ-13
MC.-32
USK-201
SK
-381
SK-382
0
0
0
0
0
SK-380
USK-200
SK-379
0
USK-202
p
USK
O
SK-378
Mc-12
°
SK-377
CI
MC14
°
SK-376
SK-12
W-2
MQ-15
SK-4
SK-10
MQ-8
Mc-7
O
Mc-23
Q
SK-1
0
Cl
0
USK-199
0
SK-375
A
MQ-17
A
SK-17
A
SK-5
0
o
MQ-10
MO--11
Mc-
W-1
MC-20
0
W-6
Explanation
Slope
Categories
0
-
5'
n5°-
10
>10
°
O
W-4:
Water
well
SK-8:
Geotechnical
borehole
Mc-12:
Trial
Pit
O
USK-380:
Existing
borehole
MC-19
p
MC-24
SK-13
SK-14
A
MC-22
0
W7
SK-2
MC-5
W-3
MQ.-4
CI
mc..-3
SK-3
MC-2
Q-21
MQ-26
MQ-1
0
VV-5
VV-4
0
Fig.
3.
Slope
map
of
Yenigehir
settlement
area.
narcik
1/
Iznik
Lake
Normal
Fault
Historical
Earthquakes
Fault
Plane
Solution
Earthquake
Sagnkudos
and
Epicenters
7
,
54,/
<8
<
7
5-5
<6
Q<•
<5
Stoke
Slip
Fault
Va
lova
aukt.
ARMUTLU
UPLIFT
Sapand
A.F.Z
ttIcL
Yenisehir
Keps
e,
.
,
kut
Dursunbe‘
ikitiebcrik
Fault
sEskoisehr
ehir
rat*
Zone
t,
0
Harman°,
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
97
31
°
BLACK
SEA
\
bul
.\.-NKOCAELI
UPLIFT
MARMARA
SEA
.
Yalova
So
'irul
2
n
0
km
20
S
A.F.Z:
Sub
Fault
Zone
AF:
Acist
Fault
ARF:Arklye
Fault
MKPAFZ:
Mustafa
Kemalpasa
A
F_Z
ADAFZ:Abant-Doicureun
A_F.Z
KKMAFZ:
Karadere-Kaynasli-Mengen
A.F.Z
\
7.4
izmit
0
_a
DAFZ
Ge`P
~
e
yve
link
r
'
erkesli
.
study
area
Iznik
Gemlik
Karacabey
1
.-
---_,
_
0
smc7
a .
-
NLake___
,
ubat
.
.S
`Bursa
Fatllti
u
w
,
C)
02
Musts
Kernalpasa
inar
Prnar
F
ao
/j
ai
O
\
Izmit
i
i
Hende
4.F:
,
Kara
plircekA.
•k
Gblyaka
o
.••
.
ar/ia
Al&
31°
Fig.
4.
Seismotectonic
map
of
Yenisehir
and
its
vicinity
(Doyuran
et
al.,
2000).
3.2.
Bursa
Fault
The
Bursa
Fault
extends
in
the
west—east
direction
for
a
distance
of
45
km
between
Ulubat
Lake
and
Bursa
municipality.
It
is
essentially
a
right-lateral
strike-slip
fault
with
an
appreciable
normal
compo-
nent.
The
most
recent
earthquake
on
this
fault
occurred
on
February
28,
1855
with
maximum
modi-
fied
Mercalli
intensity
IX
(Coburn
and
Kuran,
1985),
which
caused
extensive structural
damage
and
loss
of
lives
in
Bursa
and
its
vicinity.
The
fault
is
located
40
km
away
from
Yeniwhir
and
no
damage
was
reported
from
the
town.
3.3.
inonii-Eskisehir
Fault
Zone
The
fault
zone
extends
in
the
northwest
direction
for
a
distance
of
380
km
between
Salt
Lake
and
Bursa.
The
zone
includes
several
discontinuous
faults
with
lengths
ranging
between
a
few
kilometres
and
up
to
50
km.
Small
to
medium
earthquakes
have
been
measured
at
different
segments
of
the
fault
zone
(Fig.
4).
The
nearest
segment
of
the
fault
is
about
40
km
away
from
Yeniwhir.
The
small
faults
surrounding
the
sedimentary
basin
in
which
Yeniwhir
is
located
(Fig.
4)
are
the
closest
faults
to
the
settlement
area.
The
field
studies
indicated
USK-204A
°
0
SK-384
0
9K-3116
SK-38-5
0
USK-206A
USK
-
2015
0
USK-205B
SK-5
W
Ma
It
A
Klc-7
SK-382
SK-3133
USK-204
USK-I97
161p-36
Explanation
Quaternary
Deposits
Neogene
Deposits
W-4:
Water
well
A
SK-8:
Geotechnical
borehole
1=I
Mcl-I'L
!nal
Pit
0
LJSK-380:
Existing
borehole
I I
Line
of
section
Groundwater
contour
Groundwater
flow
direction
USK-19a
Se-11
SK-
0
3it
SK-374
K-IT
mc-is
MV-14
SK-375
A
SK-I2
Ar-2
Mc-15
A
1
141c-13
0
MC
-
24
SK-13
A
SK-14
1419-22
0
al,
9
-1
A
SK-11
Mc
0
-
98
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
that
Yeniwhir
settlement
area
is
located
within
a
fault-
controlled
Neogene
basin
and
there
is
no
field
evi-
dence
suggesting
that
these
faults
are
still
active.
At
present,
the
faults
are
mostly
concealed
by
post-Neo-
gene
deposits.
4.
Geological
setting
The
main
lithological
units
in
the
vicinity
of
Yeniphir
are
pre-Neogene,
Neogene
and
Quaternary
deposits
(Fig.
5).
4.1.
Pre-Neogene
deposits
They
are
the
oldest
deposits
underlying
the
Neo-
gene
basin.
They
form
basement
rocks
consisting
of
schists,
marbles,
meta-volcanics,
limestone
and
vol-
canics.
None
of
the
rocks
outcrop
in
the
study
area.
They
are
also
not
encountered
during
drilling.
4.2.
Neogene
deposits
These
are
essentially
detrital
sedimentary
depos-
its
consisting
mostly
of
loosely
cemented
conglom-
N
YENISEHIR
9K-6
aF
r
0
/.
250
500
750
1000
.1
1
1
1
K.
34
K-9
A
SK-6
4
Caisternery
Deposits
IT
I
Neogene
Deposits
F
7
s..
Fre-Neogene
Deposits
Fault
Inferred
Fau
Mc-13
IK-32
Mc--33
= 0
SK-37S
USN-
Sow
SK-381
-201
o
usK• 1
"
1-
,„9
7
USK-195
0
USK-19S
0
SK-373
0
0
SK-312
SK-3T1
SK-2
mg-a
0
NI-5
O
Fig.
5.
Geological
map
of
Yeni§ehir.
T
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et
al.
/
Engineering
Geology
70
(2003)
93-108
99
erate,
sandstone
and
claystone
intercalations.
The
deposits
show
both
lateral
and
vertical
gradations.
They
contain
four
distinct
zones.
At
the
bottom,
the
deposits
start
with
loosely
cemented
conglomerates.
The
gravel-boulder
size
particles
(2-50
cm)
are
generally
subrounded
to
angular.
The
particles
are
derived
from
the
rocks
of
the
pre-Neogene
deposits.
This
zone
has
a
thickness
of
50-100
m.
It
does
not
outcrop
in
the
study
area.
This
basal
conglomerate
is
followed
by
conglomerate,
sandstone
and
silt-
stone
alternations.
The
size
of
the
particles
forming
the
conglomerate
of
this
second
zone
is
relatively
small
ranging
between
1
and
10
cm.
These
particles
are
also
derived
from
the
pre-Neogene
deposits.
Above
this
zone,
a
clay-dominant
very
thick
deposit
containing
thin
sand
and
gravel
lenses
exists.
The
thickness
of
this
third
zone
ranges
between
100
and
200
m.
The
zone
is
observed
along
the
ridges
at
the
north
of
the
study
area
where
future
settlement
is
planned
(Fig.
5).
The
uppermost
part
(the
fourth
zone)
of
the
Neogene
deposits
is
characterized
by
clayey
calcareous
materials
like
claystones
and
marls.
These
sediments
have
very
local
exposures
and
they
have
a
thickness
of
less
than
10
m.
The
Neogene
deposits
unconformably
overlie
the
pre-
Neogene
deposits.
4.3.
Quaternary
deposits
The
Quaternary
deposits
are
mainly
observed
in
the
middle
of
the
basin.
These
consist
of
alluvium
and
detritus
transported
from
northern
and
southern
ridges
of
the
basin
as
sheetwash.
They
form
flat
topography
in
the
study
area.
Yeniwhir
is
mainly
located
within
this
unit.
The
deposits
include
clay
and
silt with
occasional
sand
and
gravel
interbeds
and/or
lenses.
Thick
clay
and
silt
deposits
are
dom-
inant
at
the
north
of
the
basin
and
they
are
derived
from
the
existing
Neogene
deposits.
However,
clay
and
silt
deposits
get
thinner
at
the
south
of
the
basin
near
the
Kocasu
stream
where
thick
sand
and
gravel
layers
become
dominant.
This
part
corresponds
to
the
old
flood
plain
of
the
Kocasu
stream.
However,
due
to
extensive
settlement
and
farming,
it
is
not
possible
to
precisely
distinguish
the
boundary
between
fine
and
coarse
deposits.
Based
on
the
field
observations,
the
thickness
of
the
Quaternary
deposits
exceeds
100
m.
5.
Geotechnical
evaluation
Geotechnical
studies
were
performed
for
the
as-
sessment
of
the
foundation
conditions
of
the
present
and
future
settlement
areas
of
Yeniwhir.
The
geo-
technical
studies
involved
trial
pitting,
drilling,
in
situ
testing
and
laboratory
testing
(Doyuran
et
al.,
2000).
At
Yeniwhir
a
total
of
17
boreholes
and
36
trial
pits
were
opened.
The
maximum
depths
of
individual
boreholes
and
trial
pits
are
20
and
8.5
m,
respectively.
In
addition
to
these,
36
borehole
data
belonging
to
previous
investigations
were
also
used.
Standard
Pen-
etration
Tests
(SPT)
were
conducted
at
1.5
m
inter-
vals.
The
SPT
samples
were
used
to
determine
the
index
properties
of
the
soils.
During
drilling
and
trial
pitting,
groundwater
levels
were
also
measured.
Lab-
oratory
testing
includes
determination
of
water
con-
tent,
specific
gravity,
unit
weight,
sieve
analyses
and
Atterberg
limits
of
soils
obtained
from
boreholes
(Table
1).
The
evaluation
of
the
index
properties
of
the
Neogene
and
Quaternary
deposits
shows
similar
index
properties.
However,
their
SPT-N
and
V
S
values
differ
considerably.
This
may
imply
that
the
Neogene
deposits
serve
as
a
better
foundation
material
for
the
settlement
area.
Groundwater
level
data
were
obtained
by
measure-
ments
in
geotechnical
boreholes,
trial
pits
and
exist-
Table
1
Index
properties
of
soils
Properties
Lithology
Quaternary
deposits
a
(mean
±
S.D.)
b
Neogene
deposits
a
(mean
±
S.D.)
b
Water
content
(%)
21.15
±
7.64
(49)
19.53
±
6.86
(5)
Specific
gravity
2.70
±
0.02
(17)
2.70
±
0.01
(2)
Unit
weight
(lchl/m
3
)
19.20
±
0.80
(35)
20.50
±
0.50
(17)
Liquid
limit
48.18
±
14.62
(45)
51.60
±
13.92
(5)
Plastic
limit
20.98
±
2.22
(45)
19.80
±
1.64
(5)
Plasticity
index
27.20
±
14.52
(45)
31.80
±
12.52
(5)
SPT-N
value
26
±
16.98
(127)
71
±
25.54
(17)
Shear
wave
velocity',
it
s
(m/s)
266.61
±
31.54
(127)
370.77
±
5.92
(17)
a
Values
in
parentheses
represent
number
of
tests.
b
S.D.
=
standard
deviation.
Estimated
from
SPT-N
value
using
the
equation
(V
s
=97*N
°314
)
suggested
by
Tonouchi
et
al.
(1983).
EXPLANATIONS
Light
brown,
silty
CLAY
with
sand
Reddish
brown,
silty
CLAY
Silty
SAND
with
gravel
SPT-N
value
O
100
200
400(m)
Horizontal
Scale
S
260
-
(
m
)
250
240
-
230-
210
-
190
0
1
50
0
co
0
.4
-230
-220
-
210
-
200
-190
N
(m)
28a
co
Co
se
co
40
0
•••
d
0
SE
dt
co
52
a
co
(m)
230
1
145
1
0.41er
§
NW
x
("
50
CO
210
-
200
T
.
T
o
pal
et
al
. /
E
n
gi
neeri
n
g
G
eol
o
gy
70
(2
003
)
93
-1
08
210
-
200
-
Fig.
6.
Geological
cross-sections
based
on
lithological
properties
through
Yenigehir
settlement
area.
_
C
Quaternary
Deposits
Neogene
Deposits
C)
0
00
C
°H
0
MH
or
Oil
30
40
50
60
70
80
90
100
CL
7
4
ML
!O
20
CL-ML
ML
or
OL
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
101
ing
dug
and
drilled
wells.
The
groundwater
levels
are
deeper
14
m)
in
the
north
and
shallower
(2.2-7.15
m)
in
the
south
of
the
study
area
(Fig.
5).
The
groundwater
occurs
within
the
sand
and
gravel
lenses
and/or
interbeds
of
the
Quaternary
alluvial
deposits.
Thus,
during
foundation
excavation
water
inflow
problems
are
expected
in
the
southern
part
of
the
study
area.
Distribution
of
different
lithological
units
is
deter-
mined
on
the
basis
of
field
observations,
trial
pits
and
drillings.
From
the
geological
map
(Fig.
5),
it
is
seen
that
Neogene
deposits
cover
a
small
area
in
the
north;
however,
the
rest
of
the
study
area
is
underlain
by
Quaternary
deposits.
Neogene
deposits
consist
of
light
to
reddish
brown
silty
clay
with
occasional
sand
lenses.
The
clay
is
very
stiff
to
hard
having
high
plasticity
and
high
expansion
potential
(Figs.
7
and
8).
Quaternary
deposits
consist
of
light
brown
silty
clay
with
sand
of
very
stiff
to
hard
consistency.
The
clay
layers
generally
form
the
upper
part
of
the
deposits.
Below
it,
medium
dense
to
loose,
silty
sand
with
gravel
of
variable
thickness
is
also
observed
(Fig.
6).
The
sand
layer
is
fully
saturated
and
forms
a
confined
aquifer.
The
laboratory
studies
reveal
that
the
clay
layers
of
the
Quaternary
deposits
have
both
low
and
high
plasticity
and
expansion
potential
(Figs.
7
and
8).
The
influence
of
local
site
conditions
on
the
intensity
of
the
ground
shaking
and
earthquake
damage
has
long
been
recognized
as
a
contributing
factor.
The
potential
for
significant
ground
amplifi-
cation
in
any
period
range
is
a
function
of
geologic,
seismological
and
geotechnical
factors
(Ferritto
et
al.,
1999;
Kramer,
1996).
For
the
sake
of
providing
input
data
to
a
comprehensive
microzonation
of
Yeniwhir
based
on
site
specific
soil
response,
the
soil
profiles
observed
in
the
study
area
are
characterized
in
terms
of
US
National
Earthquake
Hazard
Reduction
Pro-
gram's
(NEHRP)
soil
classification.
Average
shear
wave
velocity
(V
s
)
of
the
uppermost
30
m
of
the
ground
is
an
important
parameter
(Borcherdt,
1994;
Street
et
al.,
1997;
Ferritto
et
al.,
1999)
for
ground
characterization.
The
shear
wave
velocities
are
either
measured
directly
using
geophysical
techni-
ques
or
estimated
from
established
correlations
for
each
foundation
soil.
In
this
study,
V
s
is
estimated
6
50
40
3
20
10
Liquid
Limit
(%)
Fig.
7.
Plasticity
chart
of
the
clayey
layers.
102
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
70
60
50
20
10
0
Quaternary
Deposits
II
Neogene
Deposits
0
0
0
0
Very
high
expansion
High
expansion
U
01
'Medium
expansion
Low
expansion
I I I I I
10
20
30
40
50
60
70
Clay
Content
(%
<0.002
mm)
Fig.
8.
Activity
chart
of
the
clayey
layers.
from
SPT
data.
There
are
many
empirical
correla-
tions
between
V
s
and
SPT
(Imai
and
Yoshimura,
1970;
Ohta
and
Goto,
1978;
Tonouchi
et
al., 1983;
Okamoto
et
al.,
1989).
The
empirical
equation
(V
s
=
97*N
°314
,
where
N
is
the
number
of
blows
for
the
last
30
cm
penetration)
suggested
by
Tonou-
chi
et
al.
(1983)
is
preferred
in
this
study.
Although
the
average
V
s
value
for
the
upper
30
m
of
the
soil
is
required
for
the
soil
classification,
the
boreholes
in
the
area
are
planned
for
10-20
m
depths
because
in
most
of
the
boreholes,
the
SPT
tests
give
high
N
values
or
refusal
below
these
depths.
Based
on
the
NEHRP's
soils
classification,
the
Quaternary
depos-
its
have
an
average
V
s
value
of
267
m/s,
correspond-
ing
to
D-type
stiff
soil.
On
the
other
hand,
average
V
s
value
of
the
Neogene
deposits
is
371
m/s,
which
indicates
C-type
very
dense
soil.
Recent
building
seismic
code
provisions
proposed
by
Dobry
et
al.
(2000)
indicate
that
soil
properties
more
readily
available
than
the
average
V
s
value,
such
as
SPT-N
value
or
undrained
shear
strength
can
be
used
to
characterize
the
upper
30
m
of
soil.
The
use
of
the
SPT-N
values
for
both
the
Quaternary
deposits
and
the
Neogene
deposits
in
the
new
seismic
code
also
yields
the
same
site
categories
as
the
NEHRP's
soils
classification.
In
order
to
assess
the
behaviour
of
the
granular
soils
under
dynamic
loading
conditions,
the
liquefaction
potential
of
the
study
area
has
been
investigated
using
the
procedure
proposed
by
NCEER
(1997).
In
this
method,
cyclic
stress
ratio
and
corrected
SPT-(N
1
)
60
values
are
considered.
In
Turkey,
limited
strong
ground
SK
_
1
SK
_
2
SK
_
3
SK
_
5
o
SK
10
SK
12
O
SK
13
SK
14
USK_1913
o
USK_200
PERCENT
FINES=<
5
LIQUEFACTION
0
NO
LIQUEFACTION
M
=
7.5
a
max=
0.4
g
%F.
=<5%
C13
0
0
Ea
••
*
*
61
El*
0
0
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
103
motion
accelerometers
exist.
In
the
vicinity
of
the
site,
four
accelerometers
in
Bursa,
Iznik
and
Sakarya
were
installed
recently.
The
strong
ground
motion
data
reveal
that
the
maximum
peak
horizontal
ground
accel-
eration
for
the
close
vicinity
of
Yen*hir
was
0.40
g.
This
was
recorded
during
the
August
17,
1999
Izmit
earthquake.
The
General
Directorate
of
Disaster
Affairs
of
Turkey
also
suggests
the
use
of
0.40
g
for
areas
located
in
the
First-Degree
Earthquake
Zone
of
Turkey.
Therefore,
the
expected
horizontal
ground
acceleration
is
taken
as
0.4
g
for
liquefaction
analyses.
The
analyses
were
conducted
for
5%,
15%
and
35%
fine
fractions
(Figs.
9-11).
Liquefaction
related
sand
boils
and
surface
settle-
ment
may
be
observed
during
earthquake
shaking.
The
development
of
sand
boils
is
a
complicated
process.
It
depends
on
the
magnitude
of
the
excess
pore
pressure;
the
thickness,
density
and
depth
of
liquefiable
zone, and
the
thickness,
permeability
and
intactness
of
any
soil
layers
that
overlie
the
liquefi-
able
zone.
At
great
depth
or
in
thin
layers,
liquefac-
tion
may
not
produce
sand
boils,
but
at
shallow
depth,
lower
excess
pore
pressures
in
thick
layers
may
(Kramer,
1996).
Based
on
the
examinations
of
soil
conditions
and
liquefaction-related
damage
re-
ports
from
two
earthquakes
(1983
Nihonkai-chubu
and
1976
Tangshan
earthquakes),
the
thickness
of
the
overlying
layer
required
to
prevent
level-ground
liquefaction
related
damage
is
estimated
by
Ishihara
(1985).
This
approach
is
used
for
the
study
area
because
the
liquefaction-prone
area
is
almost
flat.
The
areas
having
liquefaction
potential
are
re-eval-
uated
using
the
procedure
described
by
Ishihara
(1985)
for
liquefaction-related
surface
damage
poten-
o.6
0.5
0.3
0.1
0
C
10
20
30
40
50
60
65
Corrected
SPT
Number
(N)60
Fig.
9.
Liquefaction
potential
of
soils
for
<5%
fine
fraction.
PERCENT
FINES
=15
SK
2
SK_3
SK_12
SK_14
LIQUEFACTION
0
NO
LIQUEFACTION
I I
M
=
7.5
a
max
=
0.4
g
%F.
=
15
%
1
104
0.6
0.5
0
0.4
1:4
ri)
("I
0.3
(/)
C.)
C.)
0
0.2
0.1
0
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
0
10
20
30
40
50
60
65
Corrected
SPT
Number
(N)60
Fig.
10.
Liquefaction
potential
of
soils
for
15%
fine
fraction.
tial
(Fig.
12).
Based
on
the
analyses,
the
southern
part
of
the
study
area,
where
Quaternary
deposits
are
located,
is
found
to
be
susceptible
to
liquefaction.
In
addition
to
this,
the
southern
part
of
the
liquefaction-
prone
area
is
susceptible
to
liquefaction-related
sur-
face
damage
(Fig.
13).
Therefore,
liquefaction-related
settlement
is
expected
in
this
zone.
Thus,
during
planning
and
foundation
design
stages,
the
liquefac-
tion
susceptibility
of
the
foundation
materials
must
be
given
due
consideration.
6.
Microzonation
Based
on
the
geological,
geotechnical,
hydro-
geological
and
seismotectonic
characteristics
of
the
Yeniwhir
and
its
vicinity,
the
foundation
materials
are
grouped
into
different
zones.
The
General
Directorate
of
Disaster
Affairs
of
Turkey
(GDDA,
2000)
recom-
mended
the
following
subdivisions:
Zone
I:
Areas
suitable
for
settlement—normal
residential
developments
can
be
planned
without
any
further
precautions.
Zone
II:
Provisional
settlement
areas—develop-
ment
can
take
place
provided
certain
precautionary
measures
against
heave,
excessive
settlements,
shallow
water
table,
etc.
are
taken.
Zone
III:
Areas
requiring
detailed
geotechnical
investigations—conditions
are
such
that
individual
investigations
are
required
and
prescribed
standard
precautions
to
be
taken
against
very
high
heave,
very
high
settlement,
very
shallow
water
table,
liquefaction,
flood,
etc.
Zone
IV:
Areas
not
suitable
for
settlement—no
settlement
of
any
kind
is
allowed
in
areas
where
PERCENT
FINES
=
35
Ski
SK
_
5
o
SK_10
SK_12
LIQUEFACTION
NO
LIQUEFACTION
M
=
7.5
a
max
=
0.4
g
%F.
=
35
%
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
105
0.6
0.5
0.1
0
0
10
20
30
40
50
60
70
Corrected
SPT
Number
(N,)60
Fig.
11.
Liquefaction
potential
of
soils
for
35%
fine
fraction.
seismicity,
landslides,
floods,
water
table
at
the
surface,
steep
slopes,
etc.
pose
serious
risks
to
residental
development.
Such
areas
may
be
used
for
recreational
purposes.
During
microzonation
studies,
special
emphasis
is
given
to
natural
hazards
such
as
earthquake,
landslide
and
flood,
as
well
as
to
the
response
of
the
foundation
materials
to
static
and
dynamic
loading
conditions.
Considering
the
earthquake
risks
and
geological/geotechnical
characteristics
of
the
foundation
material,
the
following
zones
are
identi-
fied.
6.1.
Zone
II:
Provisional
settlement
areas
In
the
north
of
the
study
area,
Neogene
and
Quaternary
deposits
are
exposed.
Here,
silty
clays
with
sand
having
very
stiff
to
hard
consistency,
high
plasticity
and
high
to
very
high
expansion
potential
are
observed.
This
part
of
Yeniwhir
is
considered
to
be
in
Zone
II
(Fig.
13).
In
this
area,
foundation-related
deformation
is
expected
for
light
structures
having
shallow
foundation
depth.
There-
fore,
in
this
area,
shallow
foundations
should
be
avoided
and
the
buildings
should
preferably
have
basement
floors
extending
below
the
zone
of
cyclic
wetting—drying.
6.2.
Zone
III:
Areas
requiring
detailed
geotechnical
investigations
Zone
III
covers
an
area
in
the
south
of
Yeniwhir
(Fig.
13).
It
is
mainly
underlain
by
Quaternary
depos-
its,
which
contain
both
clayey
and
sandy
soils
with
a
shallow
groundwater
table.
Both
high
and
low
plas-
ticity
clays
(CH-CL
type)
exist
(Fig.
7).
Low
plasticity
clays
generally
show
low
expansion
behaviour
whereas
high
plasticity
clays
show
high
expansion
behaviour
(Fig.
8).
The
analyses
of
sandy
soils
reveal
a
max
=
-
0.4g
surface
damage
4
3
2
17
16
15
14
,—,
13
cf,
11
to
•••4
0
ri)
8
La
h)
an
7
CC
(1)
5
12
9
6
no
surface
damage
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Non
liquefiable
surface
layer
thickness
(m)
0
106
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
Fig.
12.
Liquefaction-related
surface
damage
potential
of
soils.
that
this
area
is
susceptible
to
liquefaction.
The
south-
ern
part
of
Zone
III
has
higher
liquefaction
suscept-
ibility
with
a
risk
of
liquefaction-related
surface
damage
(Zone
IIIB)
due
to
settlement.
However,
the
northern
part
of
Zone
III
has
a
thicker
clayey
surface
layer
where
liquefaction-related
surface
damage
(set-
tlement)
is
not
expected
(Zone
IIIA).
The
subdivision
of
Zone
III
is
based
on
a
limited
number
of
drillings
and
trial
pit
data.
Therefore,
during
the
design
stage,
detailed
geotechnical
inves-
tigations
are
recommended
in
order
to
check
the
settlement,
expansion
and
liquefaction
potential
of
the
foundation
materials.
7.
Conclusions
and
recommendations
The
Yeniwhir
settlement
area
is
located
within
a
First-Degree
Earthquake
Zone
of
Turkey.
Thus,
it
will
suffer
from
ground
shaking
in
the
future
as
it
did
in
the
past.
The
town
is
located
over
a
gently
sloping
topography
formed
by
Neogene
and
Quaternary
deposits.
Within
the
Quaternary
deposits
clays
and
sands
are
the
dominant
soil
types.
In
the
study
area,
no
landslide
or
flood
problems
are
expected.
However,
the
northern
sector
of
Yeniwhir
is
characterized
by
clayey
soils
with
high
expansion.
In
this
area
shallow
foundations
should
be
avoided
and
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
107
SK-6
MC-35
O
SK-7
Mc-34
Zone
II
0
250
500
750
1000
SK-9
i
I
A
USK-197
USK-196
0
USK-195
0
0
0
SK-372
SK-371
(n)
USK-198
SK-11
SK
3J
--
-----
S-1
MC-32
mc -
.
1
.!
O
SK
,
USK
1
1
K-
Mc-34
f0
0
9
SK-380
itiSK
200
U
1
K
,
IMC-1
0
USK-199
9-
SK-378
0
Sit
7
1
1
°
SK
=I
M91
-376
I
,
L
SK-1
V
r
W-2
!
I
USK-204A
USK-204
0
SK-385
SK-386
0
0
03
SK-384
°
L.)
0 0
USK-205A
-
USK-205
0
uK
2
0513
O
SK-374
KyLr
,
O
.
s
--
MQ-
18\
US
Zone
III
A
° "
-
375
A
r;
_.I
SK-10-.1
Z.
114C
ji
SK-383
SK-ti
ip
1
=i
Mc-10
MC
,1
A
1SK-4
_12N-
Mc-7
L."
SK-1
-
MC-20
0
1N-6
1
Explanation
Zone
II:
Provisional
Areas
Zone
III:
III
A:
Liquefaction
-
no
surface
damage
III
B:
Liquefaction
-
surface
damage
oneJil
0
\iv-5
Areas
requiring
detailed
geotechnical
investigation
0-
W-4:
Water
well
A
SK-8:
Geotechnical
borehole
El
MC-12:
Trial
Pit
o
USK-380:
Existing
borehole
Fig.
13.
Microzonation
and
liquefaction
potential
map
of
Yenigehir
settlement
area.
108
T
Topal
et
al.
/
Engineering
Geology
70
(2003)
93-108
the
buildings
with
basement
floors
should
be
preferred.
In
the
southern
sector,
medium
to
loose
saturated
sand
lenses
and
layers
are
common
within
the
clayey
foundation.
Thus,
this
part
of
the
area
is
susceptible
to
liquefaction
under
dynamic
loading
conditions.
Considering
the
earthquake
potential
of
the
area,
the
design
stage
must
include
geotechnical
investigations
for
detailed
assessment
of
the
foundation
conditions.
Acknowledgements
The
authors
thank
Dr.
J.
Bommer
and
the
anony-
mous
reviewer
of
this
journal
for
their
constructive
comments
and
suggestions
on
the
manuscript.
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