Volume 4, Issue 3 September 2019

On-site Interview

Tide Wall Reinforcement Work by Press-in Method(Keihin Canal, Tokyo)
Hongjuan He, Secretary of IPA
Yuta Kitano, Corresponding Member of IPA Japan Branch Office

Photo 1. The children are playing
around construction site.
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Volume 4, Issue 3 September 2019

Koji Hamada
Manager, GIKEN SEKO CO., LTD.

Mizuho Yokoyama
Assistant Manager, GIKEN SEKO CO., LTD.

Mr. Hamada joined GIKEN in 1990. He had the 25years’ experience of the Press-in work at construction
sites, including the 10-year-overseas work in the USA,Canada, Mexico, etc. He engaged in this site asManager.

Mr. Yokoyama joined GIKEN in April, 1997. He has
been engaging in all the Press-in Methods including“Hard Ground Press-in Method” and “Gyro Method”
for 20 years. He engaged in this work as MainOperator.

Q1.

Would you please tell the outline of this construction work including the background?

Mr. Hamada: Tokyo Metropolitan Government is working on further reinforcing countermeasures against earthquakes,
tsunamis and high surges for low and coastal areas. This construction site, the tide wall of Keihin Canal(1chome, Yashio, Sinagawa-ku, Tokyo) (Fig.1) is part of the tide wall reinforcement work. This is a very oldtide wall constructed in 1963 by steel sheet piles and has been deteriorating as shown in Photo 2. It wasrequired to build a new steel tubular pile revetment in front of the existing tide wall maintaining the current
function of the tide wall, and it was decided to adopt a method to Press-in steel tubular piles for a newrevetment（L=24.5m,Φ1,400mm,71piles）and steel sheet piles (L=18m,Φ900mm,17 piles). The construction
was undertaken dividing the process into three steps as shown in Fig. 2.

Construction
location

Construction
location
Keihin Canal

Fig.1. Location of construction site

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From Google Map

Volume 4, Issue 3 September 2019

Photo 2. Tide wall constructed in 1963

Keihin Canal

Metropolitan
Expressway
Wangan Line
Yashio Bridge

Step 1 (17 steel sheet piles))
Step 3 (36 steel tubular piles)

Step 2 (35 steel tubular piles)

Fig. 2. Construction plan

Q2.

What kind of technological features were there in this project?

Mr. Yokoyama: Two features can be pointed out. The first is that part of the construction of steel tubular piles was carriedout under a limited overhead clearance of the metropolitan expressway and Yashio Bridge (Photo 3). In
the case of driving piles under a limited overhead clearance, usually the length of a steel tubular pile isshortened and welding points are increased. However, if joint points are increased, the cost would rise
and the construction period would be also prolonged. As a result of consideration, Y-jibu, a special
attachment that our company developed, was adopted. Y-jibu which was used in this construction is a Yshape attachment that is attached to the toe of a hanging device which a Press-in machine for low
overhead clearance is equipped with. The head is lengthened by pinching and raising steel tubular piles
with a Y-shape hook on both right and left sides, and by using the lengthened steel tubular piles, it became
possible to decrease the welding spots (Photo 4). The second is that, since the site was between the twobridges and the space for barges to put the equipment on was needed, it was quite difficult to secure theconstruction space in a narrow water area (Photo 5). That is why the GRB system that enables theequipment necessary for the construction to work on the completed piles was utilized. By constructing acontinuous wall without temporary works, we were able to clear the problem of limited construction
space (Photo 6).

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5m

Under girder

Pile top

Photo 4. Low overhead type Piler with Y-jibu attachment

Photo 3. Operating under Yashio Bridge

Photo 5. Construction view from a distancePhoto 6. GRB System

Q3. Was there anything you give a special
consideration in the schedule of this project?
Mr. Hamada: In this construction, there were a lot of welding
spots of steel tubular piles and it took much of
the working time for welding. But we were able
to shorten the process by increasing the numberof welders and complete the construction twoweeks earlier than scheduled. The completion ofconstruction as shown in Photo 7.

Q4. Did you have anything you found problematicor difficult to deal with? What kind of measures did
you take against them?

Photo 7. Completion of Press-in operation

Mr. Hamada: We carried out the construction keeping the following two points in mind at this site. First one is schedulecontrol. At this construction site, there were time zones when pile driving work could not be done on
account of the tidal level, we checked the tidal level in advance and adjusted the working time in order not
to have waiting time as short as possible. Second is the issue of environment maintenance in the vicinity ofthe construction site. In this construction, since all the work was done on the water, we were very careful
about prevention of oil spillage. Specifically speaking, we tried locating hydraulic pressure hoses at thepositions where they were seen all the time on the water using floats. If we leave the hydraulic pressure
hoses in the water, it would become difficult to check the damage condition of the hoses, and consequently,
to find the cause of oil spillage. That is why we made hydraulic hoses float on the water and conducted daily
check of them.
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Mr. Yokoyama: Since it was a construction work on the water,
we set up a scaffold around the piles formoving and carrying (Photo 8). In this way, welaid a passage on both sides of the alreadycompleted piles so that we could go back andforth smoothly around the Press-in spots.

Q5. The construction industry is now actively
working on the reform of working practices. Both ofyou have been working at construction sites formore than 20 years. Do you find any difference
between the time when you joined the company andthe present in terms of the way you work?
Mr. Hamada: Working long hours was common in theconstruction sites in Japan 20 years ago. But
our company tried hard to observe the five-dayPhoto 8. Scaffold
workweek and reduce the overtime work as
much as possible by streamlining theconstruction process, and thus we were able to make our company more appealing. Otherwise, youngengineers and competent workers would not join us. As a manager, for instance, I am taking a measure byincreasing people when necessary by grasping the workers’ labor hours on-site.
Yokoyama: When I started working on-site, there was no working manual. It was common that we learn our job bywatching the senior workers’ way of working by ourselves repeating try & error on-site. Now it is possible thatyoung generation people study the basics with the manual in the first place, then learn their work efficiently
through OJT on-site.

Q6. What does your company think about securing and cultivating young employees at this time of labor
shortage?
Hamada: In our company, the average age of the employees who work on-site is over 45, and it is the actual situationthat there are not enough middle-class personnel. It is becoming more and more important to secure andcultivate young operators. Also, since there is a big age difference between the senior workers and the young
employees who work on-site, there is a generation gap which hinders communication between them. In orderto solve this problem, we are working on establishing an OJT system to carry out cultivation young employees
strategically. Under advice from an outside consultant, we are now introducing the “Career Plan”, with whichyoung employees can envisage their future, and also the “Skill Map”, with which employees themselves check
how they are improving themselves. At the same time, since the way of cultivating young people changes withthe times, we give training for managers to teach how to cultivate young employees.

Q7.

What do you think about the future of the Press-in technology?

Yokoyama: I expect that the day will come some day when all the machines are completely automated and there is noneed for an operator to operate a machine on-site. I myself felt that there is especially a high risk at the sitesof disaster recovery through my many years’ on-site experience. If the complete automation is realized, safeand efficient construction work can be undertaken even at the sites of disaster recovery. Using the on-sitedata which I collected for a long time in GIKEN group, I will work hard to realize automation as soon as possible.
Hamada: I think in the future the Press-in technology will spread all over the world. With a population decline and aging,
it is expected that the construction demand in Japan will decrease. I strongly felt that foreign people appreciate
the Press-in technology highly while I was working abroad for ten years. I expect that we can contribute to theworld by utilizing the Press-in technology in the countries and areas that have the problems such as
earthquakes and tsunamis as well as Japan.

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Volume 4, Issue 3 September 2019★★ Comments ★★
I was very surprised at the quietness of the construction site when I saw the photos where the children at a nurseryschool were playing joyfully without any affect by the construction noise or vibration. They were watching theconstruction very interestingly. While I was talking with two engineers, I strongly felt that both of them have strong
confidence in the Press-in technology and also they were very proud of taking a leading part in making a contribution
to the society. I was deeply impressed by their attitude to make themselves grow even further through cultivating
young generation actively for the future world.

I would like to express my special appreciation to Mr. Hamada and Mr. Yokoyama, who gave their kind
response to our interviews for the second time, and the Toyo Construction Co. Ltd., the prime contractor,
and the people concerned for their cooperation.

Photo 9. Group photo (from left to right)
Mr. Yuta Kitano, Ms. Hongjuan He, Mr. Mizuho Yokoyama, Mr. Koji Hamada

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