Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

Case Studies: Use of the Gyropress Method in Tubular Pile Earth Retaining
Walls for Foundation Works in Urban Area
Tomoyuki IMANISHI
Construction Solutions Department, Giken Ltd, Tokyo, Japan
Email: imanishi@giken.com

Koji KAJINO
Department Leader, Press-in Technologies Support Department, Giken Ltd, Tokyo, Japan

ABSTRACT
Earth retaining walls for foundation works in urban area are often constructed under conditions where there are buildings
and underground structures in the neighbouring areas. These items will become the key factors in a selection of properconstruction method. Due to these backgrounds, cases have lately been seen where the earth retaining walls constructedof steel tubular piles installed by the Gyropress Method are adopted in urban area. The method can penetrate not only
stiff grounds, but also underground obstructions. It is possible to largely reduce construction period, since the earth
retaining walls can be constructed only by press-in operation without removing underground obstructions in advance. Inaddition, it is possible to construct walls even in narrow sites where enough working space cannot be secured, since thepress-in operation is conducted with self-walking on top of the already installed piles. The constructions can be
implemented with low vibration and low noise, keeping the effect on the surrounding environment to a minimum. In thispaper, with such advantages of the Gyropress Method as described above, introduced are the cases where steel tubular
earth retaining walls for foundation works constructed by the Gyropress Method are adopted in urban area.
Key words: the Gyropress Method, earth retaining wall

1. Introduction
Earth retaining walls for foundation works in urban
area are often constructed under conditions where there
are buildings and underground structures in neighbouring
areas. Photo 1 shows the construction of adjacent earth
retaining wall in urban area. It is very scarce for thestructure to be built in an open place free from existing
structures or underground obstructions. For this reason,
careful consideration should be given to, at the design
stage of earth retaining walls, the area of excavation,
locations and status of adjacent buildings, groundconditions, buried structures, which will become issues ina method selection (Motoi, Y., 2015). Under suchcircumstances like these, in earth retaining wallconstructions in urban area, it is essential to conduct
design and construction, considering not only safety andeconomy, but also effects on the surrounding structures- 475 -

Photo 1.

Construction of earth retaining wall in urban area

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

and adaptability to environments (Katsura, Y., 2015). Thatis the reason why cases have lately been seen where earth
retaining walls constructed of steel tubular piles installedby the Gyropress Method are adopted in urban area. In thispaper, introduced are the cases where earth retaining walls
constructed of steel tubular piles installed by Gyropress
Method were adopted in urban area.
2. Overview of earth retaining walls
2.1. Different types and features of earth retainingwalls
Fig. 1 shows different types of earth retaining walls
used in construction works and their classification

Fig. 1 Different earth retaining walls and their classification(Architectural Institute of Japan, 2002). Depending onwhether water shielding is required they are divided intowater pervious wall and water cut-off wall. Water pervious
wall may include soldier piles and a lagging wall.
Construction of this type of walls is relatively easy and theconstruction cost is low. Therefore, they are often used as
earth retaining walls. Water cut-off wall may be divided
into steel sheet pile wall, steel tubular sheet pile wall, soil
cement continuous wall, and cast-in-place reinforced
concrete wall. Among the earth retaining walls, soil
cement wall and cast-in-place reinforced concrete wall canbe used as the permanent structure. Earth retaining walls
are usually used for temporary purposes. However, thecases are increasing where the earth retaining walls areused as permanent structures in order to reduce
construction period or temporary work cost.
Fig. 2Gyropress Method

2.2. Advantages in the construction of earth retaining
walls by the gyropress method
The Gyropress Method (Fig. 2) is a construction
method where a steel tubular pile with cutting bits (Photo2) at the toe is rotated and pressed-in. It can penetrate not

only stiff ground such as boulder and rock, but also
underground obstructions such as existing reinforced
concrete structures. It is possible to largely reduce
construction period, since the earth retaining walls can beconstructed only by press-in operation without being
affected by underground obstructions or stiff grounds. Inaddition, it is possible to construct walls even in narrowsites where enough working space cannot be secured since
the press-in operation is conducted with self-walking on
top of the already installed piles. In addition,- 476 -Photo 2.

Cutting bits

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

an earth retaining wall constructed by the Gyropress
Method is a continuous steel tubular pile wall. Therefore,
it is possible to make it a cantilever wall structure, evenwhen the wall is high. Due to the increase in different
types of pressing-in machines, it is now possible to install
steel tubular piles with diameters ranging from 600 to
2,500 mm. Since constructions with large-diameter steel
tubular piles are now available, cases are increasing where
the Gyropress Method is adopted not only for roadretaining walls in civil engineering projects, but also forearth retaining walls in architectural projects.
3. Construction cases

Photo 3.

Photo taken at the construction site

3.1. Case study 1: extension work in an existing
structure site
3.1.1.

Construction overview

In this section, a case study is introduced where theGyropress Method was adopted to construct an earth
retaining wall in the extension work at an existing
structure site. The site is shown in Photo 3. The main
purpose of the project was to construct a new building in
the exiting property. The plan view is shown in Fig. 3. Anearth retaining wall was required between the new andexisting buildings for the construction work. Existingbuildings were supported by a pile foundation. Due toFig. 3 Plan view

restricted access to the working space in the residentialarea, heavy construction machinery to install a cast-inplace reinforced concrete wall was unsuitable. During theinitial stage, soldier piles and a lagging wall with struts
and ground anchors were considered. However, from thepoint of view avoiding ground anchors striking the pilefoundation of existing buildings, a steel tubular sheet pilewall, which enables the building of a cantilevered
structure, was adopted.
3.1.2.

The initial plan - soldier piles and a lagging

wall with struts and ground anchors
At the initial stage, soldier piles and a lagging wallwith struts and ground anchors were considered. The
typical cross section is shown in Fig. 4. As the planned
wall was adjacent to an existing building, the reduction ofground displacement was essential to prevent ground frombeing deformed. For this reason, the plan required struts
and ground anchors as a support for the main wall.

- 477 -Fig. 4

Typical cross-section of the initial planProceedings of the First International Conference on Press-in Engineering 2018, Kochi

However, two levels of ground anchors were required bythis plan and the upper ground anchor had to be installed
between the existing piles, which made the construction
project very challenging.
3.1.3.

The accepted plan – a cantilevered steel

tubular sheet pile wall
A cantilevered steel tubular wall installed by theGyropress Method was adopted as an earth retaining wall
due to lack of interference with foundation. A typicalcross-section of the construction is shown in Fig. 5. The
soil layer from the ground surface to a depth of about 10m consisted of sand and gravel and sandy clay with SPT
N-values of about 10. At a depth of the pile toe, the groundconsisted of sand and gravel, with a converted N-value ofFig. 5

Typical cross-section of the construction

about 250. Steel tubular piles used at the site had an outer
diameter of 1,500 mm with a thickness of 25 mm. Pile
length was 27.6 m, and 36 piles were installed. It waspossible to build an 8m high cantilever structure without
ground anchors or ground improvement. The site was veryclose to the existing buildings (Photo 4), but there was nodamage on the neighboring houses, and the installation of
the steel tubular piles was safely completed without any
accidents.
3.2. Case study 2: renovation work of a kindergarten
and a public school
3.2.1.

Construction overview

In this section, a case study in renovation work of a

Photo 4. Construction adjacent to the existing building

kindergarten/public school is introduced, where theGyropress Method was adopted to build an earth retaining
wall. The site is shown in Photo 5. The work includeddismantling old structures, constructing a new building,partial preservation, and aseismic renovation work. The
plan view of it is shown in Fig. 6. Constructing thebasement of the new building, an earth retaining wall had
to be installed between the new and adjacent existingbuildings.It was impossible to use ground anchors, since
they would have had to be installed under private
properties of the neighboring houses. Although a soil
cement continuous wall with struts was planned at first, asteel tubular pile wall was adopted through the deignchange to reduce the construction duration.
Photo 5.

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Photo taken at the construction siteProceedings of the First International Conference on Press-in Engineering 2018, Kochi

3.2.2.

The initial plan – a soil cement continuous

wall with struts
At the initial stage, a soil cement continuous wallwith struts was considered. A typical cross-section of thewall in the original design is shown in Fig. 7. In the design,
it was necessary to use shore struts in four layers, inaddition to a diagonal shore strut. Also, a working spacefor heavy machinery to install a soil cement continuouswall was required, while a construction of an earth
retaining wall to prevent slope failure on the private side
was necessary. This way, the original design required along construction time and labour, and was a factor toprolong the construction period.
3.2.3.

Fig. 6 Plan view

The accepted plan – a steel tubular sheet pilewall with struts

A typical cross-section of the earth retaining wall by
the Gyropress Method is shown in Fig. 8. The soil layerfrom the ground surface to a depth of 10 m consisted offill and clay with N-value of about 5. At the depth near thepile toe, the soil consisted of fine sand, with a converted
N-value of about 140. Steel tubular piles used at the site
had an outer diameter of 1,500 mm with a thickness of 25mm. Pile length was 31.0 m, and 27 piles were installed.
In the design with the Gyropress Method, earth retaining
walls are constructed of steel tubular piles. Therefore, it
was not necessary to build a soil cement continuous wall,or to prepare a construction space for heavy machinery toFig. 7

Typical cross-section of the initial planbuild the wall. In addition, since there was no excavation
involved in the installation of steel tubular piles, the earth
retaining wall to prevent slope failure on the private
property side was not necessary. Furthermore, using largediameter steel tubular piles with high stiffness, thediagonal shore strut and another shore strut were omitted.
Consequently, the work to build the earth retaining wall
was largely reduced, and the construction period wasshortened by 4 months, compared with that in the original
design which took 3 years. The fact that the construction
period was shortened and that the effect on theneighboring residential houses was minimized by a lowvibration and low noise construction was highly evaluated,
and an agreement was formed with the client for selecting
the Gyropress Method to construct the earth retainingwalls.

- 479 -Fig. 8

Typical cross-section by the Gyropress Method

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

References
Architectural Institute of Japan. 2002. Recommendation for
Design and Construction Practice of Earth Retaining forExcavation. p. 22. (in Japanese)
Katsura, Y. 2015. Current status and issues in urban earth
retaining wall construction. The foundation engineering &equipment, monthly, Vol. 43, No. 12, pp. 2-7. (in Japanese)
Motoi, Y. 2015. Management point of urban earth retaining wallconstruction and consideration to adjacent buildings. The
foundation engineering & equipment, monthly, Vol. 43, No.
12, pp. 22-25. (in Japanese)
Photo 6. Construction adjacent to the existing building

The site was very close to the existing buildings (Photo 6),
but there was no damage on the neighboring houses, andthe installation of the steel tubular piles was safely
completed without any accidents.
4. Concluding remarks
In this paper, two construction cases were introduced,
where the steel tubular earth retaining walls by theGyropress Method were adopted in urban area.
In Case study 1, the great stiffness and cantilevered
steel tubular pile wall solved the issue of the construction
site where ground anchors were unable to be installed
between the existing piles. In Case study 2, taking the bestuse of the Press-in procedure in which a wall can beconstructed, temporary works (i.e. construction to install atemporary earth retaining wall for a working space forheavy machinery or to prevent a slope beside the existingbuilding from collapsing) were not necessary and theconstruction duration could be reduced.
In the process of method selection, a steel tubular
sheet pile wall constructed by the Gyropress method might
be regarded as a dominant structure. As in the cases
introduced, it is expected that foundation works in urban
area under strict construction conditions will increase infuture. It would be very grateful, if this paper will bereferred to in a selection of construction methods, or if it
can be of some help in promoting the steel tubular pile
earth retaining walls and the Gyropress Method.

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