Proceedings of Indian Geotechnical Conference December 15-17,2011, Kochi (Invited Talk-7.)

NEW CHALLENGE IN D-RUNWAY CONSTRUCTION OF TOKYO HANEDA AIRPORT

Yoichi Watabe, Port and Airport Research Institute, Yokosuka, Japan, watabe@ipc.pari.go.jp

Takatoshi Noguchi, Kanto Regional Development Bureau, Ministry of Land, Infrastructure, Transport and Tourism, Japan

ABSTRACT: Tokyo International Airport (Haneda Airport) has been developed by land reclamation. A new runway, named

“D-runway,” was constructed from March 2006 to October 2010. Because some part of the D-runway is located in a river

mouth, a hybrid structure consisted of piled pier and reclamation fill was adopted. To overcome the difficulties in construction

on soft clay deposit, it adopted various technologies in design and construction. This paper describes about the outline of the

project, ground investigation, and designing of the D-runway structure, from a view point of geotechnical engineering.

INTRODUCTION

Tokyo International Airport (Haneda Airport) has been

developed by reclamation. The offshore expansion project

started from 1984 was an epoch-making project, in which

airport island was constructed from a dredged clay disposal

facilities in ultra-soft state (Katayama, 1991). Recently, The

fourth runway named “D-runway” has been newly

constructed (Photo 1, Fig.1). The D-runway started its

operation in October 2010 on schedule. This paper describes

about the outline of the D-runway project, soil stratigraphy,

and designing of the manmade island, from a view point of

geotechnical engineering.

OUTLINE OF THE D-RUNWAY PROJECT

The D-runway is located 600 m offshore from the previous

airport island. In the area inside the river mouth of the Tama

River, a pier structure with an impediment rate of river flow

less than 8% is adopted to ensure a sufficient flow rate during

times of floods. Therefore, the D-runway is a hybrid structure

of piled pier and reclamation fill. The length of the D-runway

is 2500 m. The elevation at the offshore end of the D-runway

is required to be higher than A.P. +17.1 m, which is

extremely higher than ordinal manmade island. Here,

elevation ±0 in A.P. corresponds to +1.134 m in T.P.

The geological cross-section in the D-runway direction is

shown in Fig.2. Soil layers are named reflecting the

geological history; i.e. Y (Yurakucho layer), Na (Nanago

layer), To (Tokyo layer), and Ed (Edogawa layer). Subscripts

c, s, and g represent clay, sand, and gravel layers,

respectively. The interface between Yuc and Ylc is almost

horizontal; however, lower boundary of Ylc is slightly deeper

around the south-west end of the D-runway (side of the

Tamagawa River). Most part of Na layer, Nac and Nas

deposited alternately. The Na layer at A-13 deposited deeper

and thicker than that at others, indicating that the Nac at A-13

deposited in an eroded valley in Tokyo layer.

STRUCTURE OF THE D-RUNWAY

Reclamation Section

Seawall type

The reclamation section was constructed on a soft clay

seabed as a high embankment whose thickness is

approximately 41 m from seabed to the top. Because of

Photo 1. A scene of the D-runway construction taken on 18

July 2010.

C-runway

3,000m

New control tower

3,000m

A-runway

Terminal 2

Terminal 1

2,500mNew international area

Parking

Passenger terminal

Cargo terminal

Garden

Apron

New runway(D-runway)

Fig.1. Site plan of the D-runway and previous airport

facilities.

41

Yoichi Watabe & Takatoshi Noguchi

consolidation settlement, the thickness is larger than the total

of the water depth and elevation of the runway. Incremental

consolidation pressure applying to the seabed surface by this

reclamation reached up to approximately 550 kN/m2. This

consolidation pressure, equivalent to that at the second phase

island of the Kansai International Airport, is the largest in the

history of the Tokyo Bay.

A mild slope rubble seawall was adopted for the general

seawall section (4144.1 m), and a gravity type caisson

seawall was adopted for the approach light seawall (100.2 m)

and tentative quay wall for the construction (221.0 m).

Mild slope rubble seawall

The mild slope rubble seawall was utilized to the general

seawall section because of flexibility for both settlement and

lateral movement. A typical cross-section is shown in Fig.3.

Sand compaction pile method with a replacement ratio of

30% (low replacement ratio SCP) was utilized to improve the

stability as a composite ground and to accelerate the

consolidation as drainages. SCP pile arrangement was 3.0 m

× 3.5 m.

In addition, soft clay seabed in front of the seawall was

dredged and replaced by sand as counterweight. The dredged

clay was cement treated and backfilled as lightweight soil.

These two technologies of counterweight and cemented

lightweight soil contribute to improve the stability of the

seawall.

Inside the Reclamation Fill

Inside the reclamation fill, the soft ground was improved by

sand drains (SD), to decrease residual settlement during the

in-service period by accelerating the consolidation behavior.

To achieve a degree of consolidation of 80% in Yuc layer

(deposited up to A.P. –35 m with a coefficient of

Yuc (Ac1) Yuc (Ac1)Yuc (Ac1)

Ylc (Ac2) Ylc (Ac2) Ylc (Ac2)

Hc

(1)

(2)

(3)

(4)

(5)

Eds1 (Ds6)Eds1 (Ds6)

Eds1 (Ds6)

Edc1 (Dc6)

Tog3 (Dg4)Tog3 (Dg4)Tog3 (Dg4)

Tos1 (Ds3)Tos1 (Ds3)

Tos3 (Ds5)

Toc1 (Dc3)

Edc1 (Dc6)

Edc1 (Dc6)

Eds1 (Ds6)

Tog2 (Dg3)

Toc2 (Dc4)

Toc1 (Dc3)Toc1 (Dc3)

btg (Dg1)

Tos2 (Ds4)

Ys2 (As2)

Nas1 (Ds1)

Nac1 (Dc1)

Nac1 (Dc1)

Nac1 (Dc1)Nac1 (Dc1)

Nac1 (Dc1)

Nas1 (Ds1)

Nas1 (Ds1)

Nac1 (Dc1)

Nas2 (Ds2)

Nac2 (Dc2)

Nas1 (Ds1)

Nac2 (Dc2)

Nac1 (Dc1)Nas1 (Ds1)

Nas1 (Ds1)Tos1 (Ds3)

Toc1 (Dc3)

Tos1 (Ds3)

Toc3 (Dc5)Toc3 (Dc5) Toc3 (Dc5)

Tos1 (Ds3)UG (ash)

TB10 18 (ash)

Nac1 (Dc1)

Nas2 (Ds2)Nac2 (Dc2)Nas2 (Ds2)

Nas2 (Ds2)Nac2 (Dc2)

N-value0 50

N-value0 50 N-value

0 50

N-value0 50

N-value0 50

N-value0 50

N-value0 50

N-value

0 50

A-8 A-9 A-10

A-11

A-12

A-13 A-2 A-1

-10A.P. (m)

-15

-100

-95

-90

-85

-85

-75

-70

-65

-60

-50

-45

-40

-35

-30

-25

-20

Nas2 (Ds2)

Edc1 (Dc6)

Tama River side (SW) Jonan Island side (NE)

Ys1 (As1)

Toc1 (Dc3)

Nac2 (Dc2)

Fig.2. The geological cross-section in the D-runway direction in original plan.

Replaced sand

Mound

Wave-dissipating blocksCover stones

RubbleRubble

Mound

Sand

Cement treated soil (pneumatic mixing)

Sand 1

Sand (counterweight)

Sand (cover)

Partition 1

Partition 2

SCP 60%

SCP 30%

SCP 60%

Parapet

Block

SD(1)-C-1

(1)-C-2

(2)-C

(2)-S

(2)-C

(3)-S Fig.3. A typical cross-section of the mild slope rubble seawall (general seawall section).

42

New challenge in D-runway construction of Tokyo Haneda Airport

consolidation cv of approximately 100 cm2/day) at 4 months

after a staged filling, the arrangement of SDs with 400-mm

diameter were set to be 2.5 m × 1.6 m. The SDs were

installed up to A.P. –35.5 m to A.P. –37.5 m corresponding to

the depth of Ylc layer. The SD installation was conducted

after placing the 1.5-m thick sand mat drainage (hydraulic

conductivity is higher than 1 × 10–4 m/s). After the SD

installation, 2.5-m thick sand layer (hydraulic conductivity is

higher than 1 × 10–5 m/s) was placed for SD head protection.

Determination of final land reclamation height

Incremental consolidation pressure from the reclamation fill

was approximately 550 kN/m2 and 300 kN/m2 near the

offshore end and near the joint section, respectively, of the D-

runway. The predicted total settlement in average was 7.2 m.

Contours of residual settlements calculated for in-service

period of 100 years are shown in Fig.4. The predicted

residual settlement along the D-runway was 0.50–0.65 m and

0.60–0.70 m near the joint section and end of the runway,

respectively. The seawall sections, where significant residual

settlement larger than 0.7 m was calculated, correspond to the

position of late backfilling, because these section was used as

either the open mouth (gateway) for ships/barges used for

reclamation filling or tentative material yard.

Summarizing the above results on the long-term settlement,

residual settlement for 100-year in-service period at the

highest point (the end) of the D-runway was expected to be

0.69 m (0.73 m after completion of filling). Consequently, in

consideration of the residual settlement, the filling of the D-

runway at the start of in-service period was decided to be

0.70 m (slightly larger than 0.69 m) higher than the design

elevation, which is required from the aviation operation.

Piled Pier Section

In the piled pier section, to conduct the construction within

the short period, prefabricated jacket structure was adopted.

A jacket unit is composed of upper steel girder and lower

steel pipe legs reinforced by truss structure, as shown in

Photo 2. Its standard dimension is 63 m in length, 45 m in

width, 32 m in height, and 1300 t in mass. Total 198 units of

jacket were installed for the main body of the D-runway.

In the assembling procedure of the jacket structure (Photo 2),

six steel pipe piles were first driven to the ground, then the

prefabricated jacket unit were set by inserting the pile heads

into the pipe legs, and then the clearance between the pile

heads and legs were grouted by mortar. After assembling the

jackets, there was a clearance of 2–3 m between two adjacent

jackets, and then a segment in adjusted dimensions were

inserted into the clearance and welded to be an integrated

body. Cross-section of the joint structure between the

reclamation and pier sections is shown in Fig.5. Piled

foundations of the jackets were supported by the bearing

layer (deeper than A.P. –80 m), which shows N-values

continuously greater than 50.

Joint Section

The joint structure between the reclamation and pier sections

is simply called as “joint section.” The joint section is a very

important structure, which takes the roles of both the seawall

of the manmade island and abutment for the joint girder. In

this project, well-foundation of steel pipe piles, which has a

good track record in bridge foundations and abutments, was

utilized (Fig.5). The well-foundation has consecutive 24

rectangle cells consisted of two parallel steel pipe sheet piles

as outer envelope and 25 orthogonal steel pipe sheet piles.

To ensure the stability of the well-foundation, which was

embedded to the bearing layer, it was required to utilize

lightweight backfill such as pneumatic mixing cement treated

soil (Kitazume and Satoh, 2003) and air-foam treated

lightweight soil (Tsuchida and Egashira ed., 2004; Watabe et

al., 2004). The lightweight backfill can contribute to decrease

the lateral earth pressure, consolidation settlement, and lateral

Fig.4. Contours of the predicted residual settlement in 100-

year in-service period.

Photo 2. A scene of installation of a jacket unit.

SCP 78%SCP 30%

SCP 60%

SCP 30%

Cover stones

Rubble mound

Columns

Beam

Steel

pipe

piles

Pavement and

Cover soils

ReclamationPire

Sand matSand

Expansion device

(Rolling leaf)

Airfoam treated soil 2 (10.0 kN/m3)

Airfoam treated soil 1 (11.5 kN/m3)

Cement treated soil 2 (14.0 kN/m3)

Cement treated soil 1 (14.0 kN/m3)

Asphalt treated layer

(1)-H

(1)-C-1

(1)-C-2

(2)-C-1

(3)-S

(3)-C-1

(5) (5)

(3)-C-1

(3)-S

(2)-C-1

(1)-C-2

(1)-C-1

(1)-H

Fig.5. Cross-section of the joint structure between the

reclamation and pier sections.

43

Yoichi Watabe & Takatoshi Noguchi

soil movement. In addition, the soft deposit in front of the

structure was improved by sand compaction piles with high

replacement ratio, to increase the lateral resistance of the well

foundation. Observational construction was conducted by

monitoring the settlement and lateral movement caused by

backfilling.

Effect of the Lightweight Soils

Cement treated lightweight soils made of dredged clay were

backfilled to the seawall. Major part of those was the

pneumatic mixing cement treated soil, which is appropriate to

large scale construction work, as a backfill of the mild slope

rubble seawall (Fig.3). In the joint section, to reduce the earth

pressure applying to the well-foundation whose height is

approximately 30 m from the seabed, pneumatic mixing

cement treated soil and air-foam treated lightweight soil were

placed at lower and upper sections, respectively (Fig.5).

Total volume of lightweight soils (pneumatic mixing cement

treated soil and airfoam treated lightweight soil) used in the

reclamation work of the D-runway project was approximately

5,500,000 m3, which was equivalent to approximately 15% of

total reclamation soil volume of approximately 38,000,000

m3. A typical mix proportions of the pneumatic mixing

cement treated soil and air-foam treated lightweight soil used

in this project are shown in Tables 1 and 2, respectively.

SUMMARY

One of the remarkable features of the D-runway is the hybrid

structure consisted of piled pier and reclamation fill. The

former section was adopted in the river mouth of the Tama

River, to ensure a flow rate during times of flooding. This

piled pier section was constructed by assembling the jackets

prefabricated in a factory yard to shorten the construction

period. On the other hand, the latter section, i.e. manmade

island, is a so called high embankment. The elevation at the

offshore end of the D-runway is required to be higher than

A.P. +17.1 m, because airplanes have to overpass a large ship

navigating nearby.

The soft subsoil under the mild slope rubble seawall, of

which allowable deformation is relatively large, and gravity

type caisson seawall, of which allowable deformation is

significantly small, was improved by SCP (low replacement

ratio) and CDM (block type), respectively. In addition,

lightweight treated soils were backfilled The upper soft

subsoil was improved by SD method to accelerate the

consolidation.

The upper soft subsoil was improved by SD method to

accelerate the consolidation, however, it was expected that

the lower clayey layer, which cannot be improved because

of the large depths, would cause a long-term settlement of

approximately 0.70 m. Consequently, in consideration of

the residual settlement, the filling of the D-runway was

decided to be 0.70 m higher than the design elevation.

In the construction of the D-runway, not only the ground

improvement technologies (SD, SCP, and CDM) but also the

new developed construction materials (pneumatic mixing

cement treated soil and air-foam treated lightweight soil)

were utilized. In addition, observational construction with

high-tech instruments for measurement was conducted.

Moreover, collaboration between geotechnical and geological

knowledge contributed to the interpretation of the ground

condition. In the-D-runway project, various technologies

accumulated through previous airport constructions were

applied to ground investigation, design, construction work, as

well as maintenance.

ACKNOWLEDGMENTS

This paper was written in collaboration with Kanto Regional

Development Bureau of Ministry of Land, Infrastructure,

Transport and Tourism, Port and Airport Research Institute,

and Joint Venture for D-runway construction in the further

expansion project of Haneda Airport.

REFERENCES

1. Katayama, T. (1991), Meeting the challenge to the very

soft ground –the Tokyo International Airport Offshore

Expansion Project. Proc. Int. Conf. Geotech. Engrg for Coastal Development, GEO-COAST’91, 954–967.

2. Kitazume, M. and Satoh, T. (2003), Development of

pneumatic flow mixing method and its application to

Central Japan International Airport construction. Proc.

Ground Improvement, 7(3), 139–148.

3. Tsuchida, T. and Egashira, K. (ed.) (2004), The

lightweight treated soil method, A. A. Balkema

4. Watabe, Y., Itou, Y., Kang, M.-S. and Tsuchida, T.

(2004), One-dimensional compression of air-foam

treated lightweight geo-material in microscopic point of

view. Soils and Foundations, 44(6), 53–67.

Table 1. An example of mix proportion for the pneumatic

mixing cement treated soil.

W/C in weight

(%)

Cement per unit weight of slurry

C (kg/m3)

Dredged clay in front of the seawall

10.2 85

Dreaded clay from Tokyo Navigation Channel No. 1

8.5 103

Table 2. An example of mix proportion for the air-foam

treated lightweight soil.

Bulk density of clay

slurry

t (g/cm3)

Cement per unit

weight of slurry

C (kg/m3)

Volumetric

percentage of airfoam

in mixture (%)

Target t = 1.02 g/cm3 ( t = 10 kN/m3)

1.196 78 19.6

Target t = 1.12 g/cm3 ( t = 11 kN/m3)

1.211 47 11.8

44