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

A Case Study by the Gyropress Method in Consideration of Neighboring
Residential Areas
Tsubasa TSUKANAKA
Technical officer, Piler division, Kajikawa Construction Co. Ltd., Aichi, Japan
Email: tsukanaka@kajikawa.co.jp

ABSTRACTThe objective of this project is to install steel tubular piles used as a temporary earth retaining wall as well as the main
wall for an open-cut structure by the Gyropress Method, because the ground was stiff, and there were some areas where
the ground surface was uneven, and the piling work had to be conducted adjacent to residential houses.
Among the technical challenges, the construction adjacent to residential houses was severe, only 1.5 m away at theclosest location. One countermeasure was taken so as to prevent objects from being scattered over the residential houses,
and the piling operation was carefully conducted within the allowable noise and vibration level. In spite of anothercountermeasure taken, slurry overflowed from the steel tubular pile, due to the stiff ground of shale layer that was prone
to plugging. It was likely that the construction would be delayed, and dust would be scattered. As a measure, pre-cutting
piles and a specially fabricated jig were used, and it was fortunately possible to solve the problem. In addition, vibrationand noise never went over the maximum required value, and the construction was completed without any complaint.
This paper introduces this construction case.
Key words: Gyropress Method, Pre-cutting, Construction adjacent to residential houses

1. OUTLINE OF THE PROJECT

some sections to install steel tubular piles were uneven. As

1.1. Location
The site is located near the interchange of thea result, the Gyropress Method, the diaphragm wall

planned expressway that about 70 % of the entire

After an overall examination, the Gyropress Method was

extension will be tunnels or semi-underground structures.

adopted for its advantageous features to the other methods,

More than 200 steel tubular piles were installed bysuch as realization of construction sustainable to

the Gyropress Method with some elevation differences.

environment, capability to press-in piles into stiff ground

Among these, 20 piles were pressed in directly into

and underground obstructions like concrete structures, andconcrete retaining wall at a high spot on the mountain sidecompact construction system.

method, and the boring hole (BH) method were compared.

where the elevation difference was large and residential
houses were densely populated.

The objective of the project was to build a temporary
earth retaining wall which acts simultaneously as a main
wall to construct an open-cut structure.

1.2. Background and Objectives of the Project
As the project was conducted in a quiet residentialarea, the client had to select a construction method in

2. STRUCTURAL TYPE AND PILING METHOD

which the environment was sufficiently taken into

2.1. Site Condition
At the site, giving consideration to nearby residents,

consideration. In addition, the ground was a stiff mudstone

vibration and noise as well as working time were limited.

layer with a maximum SPT N-value of about 250, andDelivery of construction material and equipment were

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

stopped on the weekends and on statutory holidays. A

consideration. The Gyropress Method (Press-in Methodmeasure was taken for handling not to scatter sludge andassisted with rotary cutting) was adopted, since it gives

slurry into nearby residential areas, together with a safety

full attention to nearby residential houses, not spoiling themeasure during the operation at a high spot.

local cityscape. In addition, it was adopted since the
Gyropress Method could cope with stiff ground assumed
from the soil borehole log.

2.2. Ground Condition
The soil borehole log is shown in Fig. 1. It may beseen that the ground consisted of yellowish grey
weathered mudstone with sand at depths ranging from 1 to
10 m. At depths between 10 and 15 m, the ground wascomposed of dark grey and almost uniform mudstone withmica pieces, pumice and sand. At depths ranging from 15
to 32 m, the ground was dark grey sandy mudstone withpumice, shell and mica pieces, and with occasional
mudstone. This suggests that the overall ground conditionis hard mudstone, and that the ground would be heated up

Pile toe leveland become cohesive upon rotary cutting by the Gyropress

DL=30.50

Method.
The N-value increases from 70 to 150 in a section at
depths between 3 and 19 m, while it increases from 150 toabout 200 at depths ranging from 19 to 32 m.
The site was located on a hill, and the groundconsisted of slopes with the elevation differences less than
200 m in a square kilometer. Liquefaction was judged to
be unlikely. This project was divided into two sections
which were conducted in order: the mountain side where
elevation was high; and the valley side where elevation
was low.
Currently there are no tall buildings or stations, justresidential houses are built along the slope. Judging fromthe fact that the main transportation means of nearby
residents is automobile or bus, it is recognized that this isa relatively calm and quiet area.
2.3. Structural TypeA plan view of a portion of the site adjacent toresidential houses is shown in Fig. 2. The structure of thewall is cantilevered retaining wall built with steel tubularpiles with a diameter of 800 mm. The typical crosssections of the wall are shown in Fig. 3-a and 3-b.
2.4. Piling Method
As the project was conducted in a quiet residentialarea, the client had to select a construction method inwhich the environment was sufficiently taken into

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Fig. 1

Soil borehole log

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

Fig. 2 Plan view of the site adjacent to residential houses

Retaining height

Formation level

Fig. 3-a Typical cross-sections of the wall

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

Retaining height

Formation level

Formation level

Fig. 3-b Typical cross-sections of the wallFig. 4Retaining height

Layout of the machine layout- 462 -

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

3. PRESS-IN PILING
3.1. Layout
Fig. 4 shows a layout of the site in the press-in
operation of steel tubular piles adjacent to residential
houses. The construction was carried out at the height ofabout 8 m, and the lower part of the figure was facing theresidential houses with a separation of mere 1.5 m at theclosest point. The top part of the figure shows that a
construction material and equipment are arranged on theplatform. A 90ton crawler crane is set beside a steel
tubular pile.
The construction advanced from the right to the left
in the figure. The pressing-in machine self-walked

Photo 1.

backward, and pressed-in piles in the direction from theInstallation of steel tubular piles directly into
concrete retaining wall

top to the bottom. In the operation at the corner, dummy
piles were pressed-in to reset up the pressing-in machine.
The press-in operation is shown in Fig. 5, referring
to section A-A. Piles were installed very close to theresidential houses, without removing existing structures,
directly into a concrete retaining wall (Fig. 6 and Photos1). Steel tubular piles were cut to the planned level and the

Residential Houses

ground was levelled after building a cut slope (Fig. 7).

Fig. 7

Residential Houses

Fig. 5 Press-in operation (refer to section A-A)

Residential Houses

Fig. 6

Installation adjacent to residential houses- 463 -

Cut steel tubular piles after the excavation

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

3.2. Piling Data
The press-in piling data regarding press-in and3.3. Productivity
Construction of the retaining wall lasted for about 7

extraction forces are collected in Fig. 8.

months between June 12, 2017 to January 18, 2018. The

The noise made by the heavy machinery was
minimized by reducing the rotation speed of the steel

detail information of the installed steel tubular piles isshown in Table 1.

tubular pile.

Table 1.

Note the amount of water flow supplied by the waterSpecification of the installed tubular piles

Specification

Qty

lubrication system to the inside of the steel tubular pile

800mm dia. tubular piles, t=9, L=12.5m

14no.

was kept smaller than that to the outside, so that water

800mm dia. tubular piles, t=9, L=15.5m

6no.

inside the pile would not leak out.

800mm dia. tubular piles, t=9, L=20.0m

41no.

800mm dia. tubular piles, t=9, L=24.0m

41no.

800mm dia. tubular piles, t=9, L=26.0m

28no.

800mm dia. tubular piles, t=9, L=32.5m

30no.

1,500mm dia. tubular piles, t=9, L=16.0m

24no.

1,500mm dia. tubular piles, t=9, L=18.0m

24no.

3.4. Encountered Difficulties and Measures Taken
3.4.1 Encountered difficulties
In the installation of steel tubular piles adjacent toresidential houses about 1.5 m away at the closest point, it
was likely that concrete pieces and injected water would
scatter if piles were directly pressed into the concrete
retaining wall at a high spot. In addition, to consider
vibration and noise, the torque level had to be suppressed.
When pressing-in an 800 mm diameter steel tubularpile, sludge swelled out from the inside of the pile about 3
m and hindered the driving attachment 1 setting. Soil had
to be removed manually. This took time, and daily
progress of the construction became worse. Furthermore,water sludge as well as soil sludge was erupting from thepile top, it was likely for them to scatter over nearby
The total time: 1 h 25m 06s

houses. This might have happened by the following reason.
Since the diameter of the steel tubular pile was small,when pressed into stiff ground that had been consolidated,
the ground increased its volume. Swollen soil found way① Press-in Force② Extraction Forceto the inside of the steel tubular pile, the only open space
available, and might have erupted.
By rights, this is a problem that can be solved by the
excavation before pressing-in the piles. However, the piles

Fig. 8Press-in monitoring data

had to be installed adjacent to residential houses, and it
was not possible to excavate a trench more than a certain
amount.

1

The special attachment used to drive pile until the pile
top is completely buried in ground- 464 -

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

3.4.2 Countermeasures taken
At the site, the countermeasure was taken against

shortened by about 60 minutes per pile, compared withmanual soil removal.

scattering objects. The pressing-in machine was covered
with a 10 m x 10 m curing sheet to avoid visual sense ofpressure and scattered objects. Where the retaining wall
was likely to collapse, iron plates were set as a precaution.
In addition, sprinkling water on the outside of the steel
tubular pile, powders of the ground concrete were
suppressed, and the pile was cooled down. At the lower

H beampart of the retaining wall, a supervisor was stationed.
Monitoring the vibration and noise level measuring
instrument, rotational speed of the pressing-in machine
was controlled. When vibration level reached 65dB and/or
noise level reached 75 dB that are restriction standard

Iron platevalues of this project, a red light came on.
For the eruption of sludge and slurry from inside of

Photo 2. Jig for the removal of soil inside the steel tubular

the steel tubular pile, the following measures were taken.

pileWhen the soil upheaval became more than 3 m, pre-cutting
was applied. For the pre-cutting operation, the pre-cutting
piles were fabricated using the dummy piles previously
used at the site. The use of the pre-cutting pile wasproposed and decided in consultation with the client andthe prime contractor．Since the length of dummy pile was

Pre-cutting pile

long, more than 10 m long, the piles were cut in such a
way that they could be enough in the amount to control theerupting soil, and their lengths were safe to handle. A
special jig was also fabricated to remove the soil inside theIron platesteel tubular piles. The jig was with a pointed H beam
welded vertically onto the base iron plate (Photo 2 and 3).
The soil stuck inside the steel tubular pile would not drop
just by shaking it, so the protruded part of the H beam wasinserted into the steel tubular pile, and the soil inside wasscoured off by rotating the chuck of the pressing-in
machine.
3.4.3 Results of Countermeasures
As for the countermeasure for scattering objects,
vibration and noise were lower than usual since therotational speed limit was kept, and the construction could
be carried out without a complaint from the residents. In
addition, construction was completed without scattering
sludge and slurry over nearby houses.
For the soil eruption from inside of the steel tubularpile, though not in the design for the pre-augering pile, a
toe bit was attached and used, soil removal time was- 465 -

Photo 3.

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

4. ADDITIONAL DATA
Vibration and noise levels at the time of construction

5. CONCLUDING REMARKSIn such a site like this case where the neighborhood

adjacent to residential houses are listed in Table 2. The

residents’ living should be taken into consideration as the

restriction standards for vibration and noise levels of this

top priority, it is a decisive factor in adoption of a machine

project are 65dB and 75dB. Table 2 shows average values

that enables environmentally friendly construction which

for each hour for the working time between 8 AM to 5 PM

can cope with stiff ground leaving the existing structuresand 1 hour before and after the working hours, including

intact like the Gyropress Method. Its true value isworks by other companies at site. It may be seen that nodemonstrated when installing piles adjacent to structures.

data exceeded the restriction standard values. It may be

Since it is possible to press-in piles into existing structures

said that the solid press-in operation with reduced

directly, construction could be conducted in a shorterrotational speed was successful. It may however be seen

period of time with less labor. It is really important forthat the noise level was somewhat higher than theneighborhood residents that the construction was

vibration level. It is therefore thought that paying more

completed in a short period of time, for seeing a heavy

attention to the noise level will be more desirable in future,machine in front of their houses may give them a sense ofwhen carrying out construction with consideration topressure. As in this site, to cope with the soil erupted fromnearby residents.

the inside of small-diameter steel tubular piles which wereIn addition, as a means of conversation at site, thepressed into ground that was likely to plug up, although it

workers were equipped with wireless phones, which might

might have been possible to press-in main piles, as

have contributed a little to the favorable result of thespecified in the design, the point was to accommodate pre-project.

augering pile that was not specified in the design, judging
from the effects on the construction progress and nearby

Table 2.

Values of measured vibration and noise levels

residential houses.
It is expected that the Gyropress Method will be used
more widely in future in constructions under similar
ground conditions and status by making use of the data ofvibration and noise as well as the press-in construction
data and consequently by realizing constructions inharmony with the local environment- 466 -