preliminary design and analysis for an immersed tube tunnel across

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A suspension bridge is a type of bridge, which consists of two main cables supporting the weight of the bridge and transfer the total load to anchorages and two towers. It is recommended for large distances more than 1000 m. Due to the relatively low deck stiffness, it is difficult to carry heavy live loads such as traffic loads. Thus, it is not recommended for weak foundation soil such as loose silt and sand (Murowchick 2008). A cable-stayed bridge is a variation of the suspension bridge and is designed for intermediate lengths between 1000 m. and 2000 m. However, its principle and construction method is quite different from a suspension bridge. For instance, the cablestayed bridges have tall towers like suspension bridges, but the roadway is attached to the towers by a series of diagonal cables. Such bridges are much lighter and stiffer compared to suspension bridges. This leads to a less deformation of the deck under the live loads. In addition, they are economic and construction time is shorter than the suspension bridges because cable stayed bridges do not need anchorages (Huang, et al. 2005). A floating bridges is connected on top of pontoons that float on water. Due to the advantage of natural buoyancy of water, the total load anchoraged to the soil can be reduced. Therefore, it is more practical solution than other bridges types when the waterbed is extremely soft. However, floating bridges is appropriate for large water depths (30 m-60 m) (Watanabe and Utsunomiya 2003). 1.4.2. Underwater Tunnels: Underwater tunnels are preferred when the soil profile of the waterbed or the weather condition is not proper for a bridge to be constructed above water. There are three alternative underwater tunnel types for crossing the water: Bored tunnels, floating tube tunnels, immersed tube tunnels. Bored tunnel shall be constructed when the ground or waterbed is appropriate for excavating and preferred for deep tunnels. There are two alternative methods to build a bored tunnel: Drilling-blasting method or by using a tunnel-boring machine. Although a TBM machine with a circular cross-section excavates the soil without disturbing it and produces a smooth tunnel wall, bored tunnel is only suitable for selfretaining soils (TCRP Report/NCHRP Report 2006). 7
A submerged floating tunnel also known as an archimed bridge is a very new concept in the world. Only, Norwegian and Chinese have submerged floating tunnel projects in the design phase. Unlike the traditional underwater tunnels, submerged floating tunnel (SFT) is not buried to the seabed; it is suspended above the water floor and anchoraged to the ground with pontoons. It requires less substructure and excavation compared to the other two alternatives. Nonetheless, SFT is only appropriate for fjords, deep seas, and deep lakes (Hakkaart, et al.1993). An immersed tube tunnel is made up of many prefabricated tubes constructed on land, which are then floated and moved to its dredged location by romorks in the sea. The tubes are lowered and connected with each other underwater. Then, the water is pumped out and the segments are covered with the backfill materials. It is preferred if the water depth is not larger than 60 m. and the waterbed is suitable for dredging, such as soft sandy, silty or alluvial soils(Baltzer and Hehengeber 2003). 1.5. Soil Profile of the İzmir Bay Bottom İzmir Bay seabed consists of mixture of very loose silt, sand and alluvial materials, which are either non-cohesive or have very low cohesion values. Moreover, the rock layer depth is found approximately at 50 m below the sea level in the Üçkuyular side and 250 m-280 m below the sea level in the Çiğli side. Therefore, its ultimate bearing capacity is very low. Moreover, since the water depth of the İzmir Bay is less than 25 m, this is an advantage for an immersed tube tunnel to be built. Considering these properties, it has been decided that the immersed tube tunnel type of construction is the most suitable one for crossing the İzmir Bay. 1.6. Application History of the Immersed Tube Tunnel The important immersed tube tunnels were listed below (Grantz, et al. 1993): The immersed tube tunnel was heard firstly in the world in 1910 with the construction of the Detroit River Tunnel between USA and Canada. This immersed tube tunnel has been constructed 24 m below the water level and consists of eleven pieces of tubes. Each tube length is 80 m, height is 9.4 m, and width is 17 m, yielding to a total length of 800 m. 8
Page 1: PRELIMINARY DESIGN AND ANALYSIS FOR
Page 4 and 5: ABSTRACT PRELIMINARY DESIGN AND ANA
Page 6 and 7: TABLE OF CONTENTS LIST OF FIGURES .
Page 8 and 9: 5.3.2. Calculation of Racking Defor
Page 10 and 11: Figure 5.6. Simplified frame analys
Page 12 and 13: 1.1. Purpose CHAPTER 1 INTRODUCTION
Page 14 and 15: approximately 40000 vehicles use th
Page 16 and 17: 1.3. Scope of This Study This study
Page 20 and 21: On the other hand, the first immers
Page 22 and 23: Max. 9 m. Figure 2.1. The possible
Page 24 and 25: Figure 2.3. The technical propertie
Page 26 and 27: IMMERSED IMMERSED TUNNEL TUNNEL UNI
Page 28 and 29: It is recommended that, the allowab
Page 30 and 31: Reduction factor Rw 1,0 0,9 0,8 0,7
Page 32 and 33: Table 3.1 The SPT results obtained
Page 34 and 35: a.) First method: The allowable bea
Page 36 and 37: intolerable settlement, before it f
Page 38 and 39: DEPTH (m) 12.0 18.0 0 0 3.0 6.0 9.0
Page 40 and 41: 3.2.2.2. Depth Reduction Factor The
Page 42 and 43: Table 3.2. The correction factor va
Page 44 and 45: ⎛ 0. 34⋅ g ⎞ ⎛189. 92 ⎞ C
Page 46 and 47: CRR = 0. 02 …. FS CRR = CSR FS =
Page 48 and 49: CHAPTER 4 STATIC ANALYSIS FOR PRELI
Page 50 and 51: Figure 4.1. Influence factor If for
Page 52 and 53: 4.1.3. Application of the First and
Page 54 and 55: 4 ⋅ 213203 + 402944 ( ) = = 25115
Page 56 and 57: Figure 4.3. The weights for vertica
Page 58 and 59: ( 1/ 3) ⋅ ( 175000) ⋅ ( 212) 12
Page 60 and 61: a) Pressure transferring on the b)
Page 62 and 63: Wsemifilled _ tube tube water W > F
Page 64 and 65: settlement value is a serviceabilit
Page 66 and 67: 5.1. Types of Deformations The resp
Page 68 and 69:
5.2.1. Free-Field Deformation Appro
Page 70 and 71:
and also underground structures are
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The maximum bending strain is calcu
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1. There is a larger deformation du
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Table 5.2. Ratios of peak ground ve
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τ F = τ soil structure Gs ⋅ B F
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R= Structure Deformation Free-Fluid
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where, the N value was taken as 4 i
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For free field axial strain: Vs a 2
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V d = M max V d 2 10 π = 4. 016 ×
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where DL is the dead load coming fr
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order to strengthen the structure a
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z y x The max stress in lateral dir
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In the equation above, 20 is the le
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max lateral displacement 0.04 m Fig
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number of assumptions (See Table 5.
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provide the dewatering activity bet
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(x1,y1) th 36 immersed tube unit θ
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∆opening = tan( 0. 0036) ⋅ 39.
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4. Durability can be extended. Ther
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values are less than 11. The applic
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Compaction grouting applications:
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value should exceed 15 in the first
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6.3.2.2. Liquefaction Analysis by u
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Table 6.1. The Situation of soil be
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6. The response of the structure du
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REFERENCES Akimoto, K., Y. Hashidat
Page 122 and 123:
Murowchick, Robert E. 2008. Bridgin
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preliminary design and analysis for an immersed tube tunnel across

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