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ENGINEERING STRUCTURES DESIGNED WITHIN THE SCOPE OF NORTHERN
MARMARA MOTORWAY PROJECT
Esra Namlı(1), Necdet Çilingir(2), Mehmet Erinçer(3), S. Şehnaz
Aktaş(4), Demir H. Yıldız(5), M. Cem Dönmez(6)
(1)Civil Engineer (B.S, M.S), Emay International Engineering and
Consultancy Inc., Istanbul, Turkey (2)Civil Engineer (B.S), Emay
International Engineering and Consultancy Inc., Istanbul, Turkey
(3)Civil Engineer (B.S, M.S), Emay International Engineering and
Consultancy Inc., Istanbul, Turkey (4)Civil Engineer (B.S, M.S),
Emay International Engineering and Consultancy Inc., Istanbul,
Turkey (5)Civil Engineer (B.S, M.S), Emay International Engineering
and Consultancy Inc., Istanbul, Turkey (6)Civil Engineer (B.S,
M.S), Emay International Engineering and Consultancy Inc.,
Istanbul, Turkey
Abstract Istanbul, being the most important city of Turkiye with
respect to economical and social-cultural considerations, lies
among the most heavily populated urban areas throughout the world.
The need for the implementation of new transportation solutions
arising from the increasing population and the economical potential
of the city as well as the strengthening of the existing
transportation network, is of paramount importance. Accordingly,
this paper is concerned with the design of engineering structures
and tunnels under construction within the scope of Northern Marmara
Motorway which has been tendered by General Directorate of
Highways. In this paper due information is given on the designed
engineering structures and tunnels and the design phase starting
from the field activities. Different solutions which had to be
adopted during the design stage and construction period has been
described in this paper. In particular, viaducts V26 and V27 has
been treated in detail with respect to soil-structure
interaction.
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1 Introduction
The aim of the Northern Route, being within the scope of the 3th
Bosphorus Crossing Project, which begins at Bagcılar and ends at
Sultanbeyli district, is to reduce the traffic volume on the
existing highway network and thereby minimize the fuel consumption
and detrimental effect on the environment as well as ensuring a
more comfortable crossing of the Istanbul Bosphorus in a shorter
time. Furthermore, the Ankara - Sincan – Cayırhan – Adapazarı –
Istanbul high speed railway line transportation system will use the
3th Bosphorus Bridge which is under construction at present. The
highway route which is under construction within the scope of the
Northern Marmara Motorway (NMM) Project, consist of 4 different
section of motorways and connecting roads both on the Asian and
European side ( Figure 1). The route includes 20 interchanges 2
tunnels (Camlık and Riva tunnels), 35 viaducts, 53 overbridges, 44
underbridges, 8 river bridges as well as close to about 300 small
engineering structures. The regional map of the route constiting of
4 section is depicted at Figure 1.
Figure 1 Regional Map of the Route
The chainage relating to the sections pertaining to the route is
given in Table 1 as follows:
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Table 1 The sections of the route with the corresponding
chainages
Side Section Range of Chainage Purpose
Europe 1 0+018,618 – 21+479,093
İstoç – Odayeri
Connecting Road
2 61+503,462 – 87+307,639 Odayeri – Garipçe Main Highway
Asia 3 88+715,639-123+118,794
Poyraz – Paşaköy Main Highway
4 0+000,000 – 12+764,391 Çamlık - Reşadiye
Connecting Road
Soil investigations have been conducted on the route consisting
of the 4 sections constructed within the scope of the Northern
Marmara Motorway Project by carrying out field observations, soil
boring tests and trial pits. The results of such investigation
work, together with that of the soil laboratory tests conducted on
soil samples have been jointly evaluated on soil samples have been
determined; thus it was then possible to carry out critical cut and
fill analyses and determine the incline of slope. It was then
possible to determine the particular geological layer on which the
foundations on the engineering structures located on the route
(under bridges, over bridges, viaducts and retaining walls) rest.
The Çamlık and Riva Tunnels being under constructed within the
scope of Northern Marmara Motorway (Bosphorus Crossing) Project is
unique in Turkiye with respect to cross sectional area. Both
tunnels being the largest in Europe and the third largest in the
World, was designed as double tubes, each tube containing 4 lanes
(Figure 2). The tunnels of which the design and construction work
continue, are located at medium depths. The maximum excavation
depth and maximum excavation width of Riva Tunnel with 196 m2
excavation area is 11m and 21m respectively. As for Çamlık Tunnel
with 225 m2 excavation area, the maximum excavation depth and
maximum excavation width is 13m and 21m respectively.
For both tunnels the expected traffic speed of 80 km per hour;
the length of the right tube and the left tube is 564m and 624m
respectively for Riva Tunnel, and 651m and 552m respectively for
Çamlık Tunnel. These tunnels are excavated by using the NATM
excavation method, encountering different rock conditions. The two
tunnels have different load capacity and different excavation
stages and bracing types.
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Figure 2 Tunnel Cross- Section
There are 35 viaducts within the Route, of which 3 viaducts
(V06, V14,V17) have been constructed by the incremental launching
method. Other viaduct were designed as consisting of precast-
pretensioned prestressed concrete girder type of superstructure.
Due to the dimensions and to the geological layers at foundation
levels, V26 and V27 viaducts have been dealt with in detail in this
paper.
2 V26 and V27 Viaducts
Viaducts V26 and V27 located within the scope of Northern
Marmara Motorway Project have 25 spans with a total length of 1005,
10 m and 19 spans with a total length of 782,25m respectively. For
each viaduct, the individual span length is 43m and deck width is
22mx2. The pier heights vary with a maximum of 50m. Each viaduct
consist of North and South bridges each accommodating 4 traffic
lanes. (Figure 3). As a result of the geological and geophysical
investigation work conducted at such viaducts which cross over the
Riva river valleys, it was observed that the viaduct foundation
would rest on the 40m thick sedimented Riva rock. It was further
observed that the region lies within the 2. Seismic Zone and thus
liquefaction risk would be high. Consequently, special geotechnical
solutions have been proposed for the viaduct foundation system.
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Figure 3 Locations of V26 and V27 Viaducts
Upper cretaceous old Sarıyer formation layers and alluvium
layers exist on the investigation area concerned. In the Sarıyer
investigation area, generally speaking, siltstone-mudstone layers
exist with dark grey sandstone layers in between for the V26
Viaduct (Figure 4).
Figure 4 V26 Viaduct Geological Map
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In the work area, 11 soil boring tests with various depths and
geophysical investigations at 6 locations have been carried out on
the planned road alignment. Table 2 shows information concerned
with certain soil boring tests for the viaducts performed at
alluvium formation at valley bottom.
Table 2 Standard Penetration Test (SPT) values corresponding to
alluvium stratum
Soil Boring Test No
Alluvium Thickness
SPT N30 Values Soil Type
AS-74 36 m 11-9-10-7-7-13- 7-10-15-15-16-19 Clay with small
amount of sand
AS-75 37,5 12-20-32-13-5-4-4- 5-6-6-5-4-5-5-5-6-8 Sand with silt
and Clay with small amount of sand
AS-76 30 m 13-17-13-8-12- 11-8-8-13-14 Sand with silt and Clay
with small amount of sand
During the work, SARA Cable Seismograph with 24 channels and 4.5
Hz central frequency geophones have been used as engineering
seismograph. Seismic energy has been provided by a mechanism
allowing simultaneous blows by 6 hunting cartridges into the earth.
Data has been collected by 2 perpendicular lines on the ground. The
line lengths vary between 40 to 190m. The geophone spacing was 2m,
3 shots were made at each line, one at the center and others at
each end. The shooting distance at each end of the line is 1m. The
lines which are parallel to the longitudinal axis of viaduct are
numbered as KS1, KS2, KS2a, KS3, KS4 and KS4a. A comparison of the
geophysical investigation reveal that they are compatible (Figure
5).
Figure 5 Geophysical Investigation Conducted for Viaducts
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An evaluation of the geological and geophysical investigations
described earlier revealed that the Riva alluvium is weak soil with
high risk of liquefaction. By considering the results of liquid
limit, water content and ratio of line-grained soil ratio as
obtained from the experiments, the liquefaction potential has been
evaluated accordance with the approaches proposed by Marcuson Vd.
(1980), Seed and Inriss (1982) with Andrews and Martin (2000).
According to such approaches the results pertaining to soil samples
taken from alluvium correspond to risky regions with liquefaction
potential, requiring special investigation.
In order to form a basics for the geotechnical and statical
calculation for viaducts V26 and V27 a non-linear time history
analysis was carried out by using Plaxis 2D software and 3 sets of
land movement which are scaled in accordance with the design
spectrum corresponding to earthquake with average 475 years return
period (earthquake with an occurrence probability of 10% in 50
years). Special land movement investigation has been carried out by
Bosphorus University, Kandilli Observatory and Earthquake Research
Institute for the Northern Marmara Motorway V26 and V27 viaducts.
As a result of analyses, it has been decided to apply jet-grout
columns so as to limit the horizontal and vertical deformations
resulting from seismic forces by providing extra support to
counteract the soil shear stresses and also to increase the safety
factor against liquefaction risk for viaducts V26 and V27 piers
situated at alluvium soil.
Considering the viaducts in question without jet-grout columns
in particular, non-linear calculation was carried out by modelling
the bridge deck as without mass by using the Plaxis 2D software, as
a result of which displacement-time values were obtained at
foundation level for each pier. However, it was observed from the
analyses made without jet-grout columns that the moment values
reach a maximum at the rock-alluvium interface. Consequently,
additional analyses were made with jet-grout columns in order to
limit the horizontal and vertical deformation resulting from
seismic forces by providing extra support to counteract the soil
shear stresses and also to increase the safety factor against
liquefaction risk for piers where ground water level correspond to
alluvium layers. In the solutions including jet-grout columns the
cohesion and unconfined compressive strength of the upper alluvium
layer has been increased and accordingly soil became stiffer (as
compared to earlier case without jet-grout column), load bearing
capacity increased and probable settlements reduced.
By virtue of jet-grout columns horizontal loads acting on piled
foundations and the relevant deformations were decreased where
liquefaction risk exists. The repetitive shear stress ratio which
soften and in fact liquefy the soil has dropped as the seismic
shear stresses were partly counteracted by jet-grout columns, as
indicated by liquefaction analyses including jet-grouting.
For these viaducts, displacement-time values deduced from Plaxis
2D were used horizontal movement entry data by using non-linear
calculation models in Sap2000. A maximum of maximum values of
plastic deformation obtained has been taken for each seismic record
as a result of analysis. Total curvatures were obtained by
converting plastic curve values into plastic curvatures and
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subsequently adding them to the yield curvatures. The total
curvatures were then compared with the concrete compression and
steel tension values at locations where moment-curvature
relationships were obtained at piers. Finally, all piers in this
viaduct which had been designed by carrying out linear analysis
were found to satisfy limited damage (LD) performance level
corresponding to an earthquake with 475 years average return
period.
The analysis model, total horizontal displacement distribution
and displacement-time graph deduced from Düzce seismic record
obtained by using Plaxis 2D software is given below for viaduct V26
at Figure 6, Figure 7, Figure 8 respectively.
Figure 6 V26 Viaduct Plaxis Model
Figure 7 V26 Viaduct Total Horizantal Displacement Graph
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Figure 8 Displacement –Time Graph for Düzce Seismic Record
3 Conclusions
The design work had to be completed in a short time, as the
Northern Marmara Motorway Project had been tendered by Build
Operate Transfer (BOT) method. This time shortage had no negative
effect on construction quality, time schedule and design work. All
necessary measures had to be taken to maintain the necessary
project quality and the Northern Marmara Motorway Project has been
implemented meticulously, as this is a prestige Project for our
country.
References
1. General Directorate of Highways (1973) Technical
Specification for Road Bridges. 2. Turkish Republic Ministry of
Public Works and Settlement (2007) Specification for Buildings
Built in Seismic Areas. 3. General Directorate of Highways,
Department of Business (2012) Criteria Reports. 4. American
Association of State Highway and Transportation Officials (2002)
Standart Specifications. 5. Erdik M (2014) Views on Seismic Design
of Northern Marmara Motorway V26 and V27 Viaducts and Determination
of Design Based Seismic Ground Motion. 6. Durgunoglu H T (2004) The
Use of High Modelled Columns in Foundation Engineering, Bosphorus
University, Kandilli Observatory. 7. Istanbul Technical University
Soil Mechanics and Foundation Engineering Istanbul 10. National
Congress