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

The Press-in Method Assisted with Augering: Case studies of Single U and
Double Z Shaped Piles in the United Kingdom
Masafumi YAMAGUCHI
Deputy Manager, Press-in Technologies Support Department, GIKEN LTD., Tokyo, Japan
Email: yamaguchi@giken.com

Kensei YAMADATechnical Manager, Technical Department, GIKEN Europe B.V, London, England

ABSTRACTOne of the key issues of pile installations is ground condition. In the case where the ground condition is stiff or hard,much efforts are required to secure the pile drivability of piles, workability of construction plant, and stiff response ofretaining walls. Since the Press-in Method was developed in 1975 in Japan, efforts had been made to develop the
penetration technique assisted by augering. Finally, a pressing-in machine against hard ground was manufactured in 1997.
Since then, the machine has been improved until now and this penetration technique has been recently utilized in the UK
as well. This paper introduces the penetration technique of the Press-in Method assisted with augering and the use of it
in two case studies, A465 Heads of the Valleys Road Section 2 in Wales and the Thames Tideway tunnel in the central
London. Finally, the installation of single U and double Z shaped sheet piles by Press-in assisted with augering arecompared in terms of their pile drivability, workability and wall stiffness.
Key words: Press-in assisted with augering, single U piles, double Z piles, augering area

1. Introduction
The Press-in Method was developed in 1975 with theconstruction industry, thus we describe some advantagesof them.

world’s first “reaction based” (GIKEN, 2008) hydraulicsteel sheet pile jacking machine. Since then, this uniquepiling technique has been achieving environmentally

2. Applicable prefabricated piles
Most of the pre-fabricated piles on the global market

friendly and suitable pile installations. Particularly, due tocan be applied to the Press-in Method. Among them, two

the demand of installations into stiff ground, the Press-in

popular and typical sections of steel sheet piles are

Method assisted with augering has recently become

introduced as follows.

popular all over the world. On the other hand, there arevarious types of prefabricated piles nowadays (i.e. steel

2.1. U shaped steel sheet piles / U Piles

sheet pile, tubular piles, H beams and others) in the world,

Among steel sheet piles, U piles are available inand the latest pressing-in machines can be applied to them.

many sizes, typically effective width of 400, 500 andThis paper describes two types of steel sheet piles

600mm (Fig. 1). They are used e.g., for levee protection

currently popular in the global market, the penetration

and road retaining walls. In Japan, they are often utilized

technique of the Press-in assisted with augering and two

for temporary cofferdams and earth retaining walls due tocase studies of the installation of single U-shaped steel

their durability against repeated use. As the cross section

sheet piles (Hereafter, U piles) or double Z-shaped pairis symmetrical, they can form a continuous wall with ansteel sheet piles (Hereafter, Z piles) in the UK, which are

effective sheet pile height twice as long as that of a single

often utilized as walls and/or foundations in today’s

sheet pile. However, care must be taken since the- 541 -

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

interlocks come on the neutral axis where the shear stressresistance. The technique is classified into two;reaches the maximum value. It is necessary to consider

simultaneous augering and pre-augering.

interlock efficiency to reduce sectional performance due

As shown in Fig. 3, in the simultaneous augering, theto insufficient shear transmission at the interlock (IPA,

hard ground at the pile toe is bored by a smaller auger head2016).

than widths of sheet piles, and a hollow space is created.
Piles/sheet piles are then pressed-in while extracting theauger, which is termed “Press-in operation withsimultaneous augering”. The technique can minimize therange of excavation and can reduce the risk of settlementof surrounding ground (IPA, 2016).

Fig. 1

Typical cross-section of U piles
Augering area

2.2. Z shaped Steel Sheet Piles / Z Piles
Z pile comes in superior in terms of cost efficiency
since the interlocks are positioned farthest away from theneutral axis, it is not necessary to consider the interlock
efficiency and the amount of steel per unit wall can be
reduced. The piling of Z piles is often conducted with two
previously interlocked piles mostly fabricated in a factory

Press-in operation withsimultaneous augeringor occasionally done on site, which is called double Z piles(Fig. 2). Double Z piles have more efficiency in cost andFig. 3Extracting the auger
after completion of installation

Procedure of Press-in operation with sumultaneousaugering

productivity when compared with single piles (IPA, 2016).

3.2.2. Press-in operation with pre-augering
For ground and rock mass with a converted SPT Nvalue* over 75, pile installation is conducted by the“Press-in operation with pre-augering”. The Press-in
Fig. 2operation with pre-augering is a technique that installs

Typical cross-section of Z piles

piles/sheet pile in two steps. The first procedure is pre3. Penetration techniqueaugering with an auger with the diameter covering most of

3.1. Selection of driving assistanceIn the Press-in Method, standard press-in operation

the section of the sheet piles down to the necessary depth

for soft ground conditions, or those with driving assistanceis the pile installation with simultaneous augering with asuch as water jetting for medium dense or stiff groundsmaller diameter auger, as explained in 3.2.1. The

conditions, augering or rotary cutting for hard groundprocedure is shown in Fig. 4 (IPA, 2016).

and backfilling while extracting the auger. The second step

condition are selected according to the ground conditionand embedded length. The primary purpose of these

3.3. Selection of auger heads
Several auger heads can be selected based on the soil

driving assistances is reduction of the toe resistance,
which could also reduce the noise and vibration during thelayer and stiffness to secure the drivability of it.

operation.
3.2. Press-in assisted with augering
3.2.1. Press-in operation with simultaneous augering
Augering is driving assistance by a Pile auger , which

Note: A converted N-value is applied for an N-value

is a part of a pressing machine, to reduce penetration

strokes) x 30 (cm) / penetration depth after 50 strokes (cm).

greater than 50 where converted N-value = N value (at 50- 542 -

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

equipped with hard teeth.
3.3.3. Auger heads with zooming blades
Pre-auger heads are quite useful for drilling into stiff
ground, however, they should be replaced withsimultaneous auger heads before the installation of sheet
piles due to their size, unless it cannot be extracted after
the completion of the process of the Press-in operation
with simultaneous augering. The replacement requires
some time, which may decrease the productivity.
For such a case, auger heads with zooming blades weredeveloped (Fig. 7). Essentialy, these auger heads are utilized
in the Press-in operation with simultaneous augering. Whilea sheet pile is being pressed-in, the auger head is rotating
clockwise and the zooming blades are spreading, whichenables the augering area to widen, e.g. 685mm diameter
augering area for 600mm width single U piles. On the other
hand, the Pile auger can be extracted by the auger headrotating anti-clockwise which enables the zooming blades toclose. It means that the replacement of the auger heads is not

Fig. 4 Procedure of Press-in operation with pre-augering
1) Pre-augering by a large diameter auger head; 2)

required and the productivity is improved. Note that auger

Extraction of auger (backfilling by reversed rotation ofheads with zooming blades may not be applicable forauger); 3) Changing to a small diameter auger head,extremely hard ground conditions as their joints between theand pile installation with simultaneous augering; andmain body and the wings be damaged.

4) Completion of Press-in operation (extraction of thesmall diameter auger and backfilling).

3.3.1. Auger heads for press-in operation withsimultaneous augering

Fig. 5

Simultaneous auger head for 600mm width U piles

Fig. 5 shows a simultaneous auger head, which has twowings, to install 600mm width single U piles. The diameteris 400mm as it shall be extracted after installing a sheet pile.
Generally, this type of auger head can be applicable formedium dense, relatively stiff ground which consists of sandand gravel with the SPT N value less than 50.
Fig. 6 Pre-auger head for 685mm width U piles

3.3.2. Auger heads for press-in operation with preaugering
The installation of sheet piles into extremely stiff
ground such as rock mass or buried obstructions are often
required due to the site condition. In that case, the toughand durable auger heads should be essential.
An auger head utilized for a Press-in operation with

Fig. 7pre-augering for 600mm width single U piles is shown in
Fig. 6. It can drill into stiff grounds, using three wings- 543 -

Auger heads with zooming blades for 600mm width U
piles

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

3.4. Selection of pressing machines
Since the first world’s “reaction based” machine wasTable 1.

developed in 1975, various machines exclusively

Max. Press-in Force

820kN(84t)

applicable for pre-fabricated steel/concrete piles haveMax. Extraction Force

1,200kN(122t)

been manufactured (GIKEN, 2017).

Total Weight*

18,450kg

Specification of ECO700S in Supe crush mode

SILENT PILER GV-ECO700S (Main body)This section introduces a couple of machine models

Pile Augerin Super crush mode for 600mm width single U piles andAuger torque28 - 62 kN.m

1,400mm width Double Z piles, which are popular on the

Total Pile Auger Weight(for 21 m pile)

11,000 kg

global market at present.
Table 2.

3.4.1. Silent Piler ECO700S in super crush mode
Silent Piler ECO700S is capable to install either 600-

Specification of Super crush SCZ675WMG

Super Crush SCZ-675WMG (Mainbody)

750mm width single U piles or 575-708mm single Z piles
by the change of the Chuck and Lower assembly parts.
Also, this model provides greater performance in various

Max. Press-in Force

1,300kN(133t)

Max. Extraction Force

1,400kN(143t)

Total Weight

27,400 kg

Pile Auger

ground conditions and site environments through the
Versatile Penetration system, which are Standard mode,
Water jetting mode and Super crush mode, with optional

Auger torque100 kN.m

Total Pile Auger Weight(for 21 m pile)

18,400 kg

auxiliary accessories.
Table 1 and Fig. 8 show the machine specificationand the machine schematic diagram.
That in Super crush mode consists of a machine main
body, a Pile auger including a motor, casings, augers andauger head, a Casing chuck and a Hose Reel.
3.4.2. Super Crush SCZ675WMG
Super Crush SCZ675WMG was developed to install
1,060-1,416mm width double Z piles (580-708mm perpile), 1,200mm and 1,400mm width double U piles (600
and 700mm per pile). Unfortunately, only Standard andWater jetting mode can be applicable for double U piles at

Fig. 8Figure of ECO700S in Super crush mode

Fig. 9Figure of Super Crush SCZ-675WMG

present, however, Super Crush mode can be applicable for
installations of double Z piles.
Table 2 and Fig. 9 show the machine outlook and thetechnical specification. Due to the size of double Z piles,
the machine size grows bigger and heavier than ones for
single U piles, meaning a wider working space is essential.
On the other hand, productivity is improved by installing
two single piles at the same time.

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

4. Case studeies in the UK

Press-in operation with pre-augering was effective against

4.1. Case study 1: A465 Heads of the Valleys Road

rock mass. After pre-augering, the steel sheet pile was
successfully installed by simultaneous augering.

Section 2
4.1.1. Summary of the site
The A465 is recognised in the Welsh Governments
National Transport Plan as a strategically important route.
The scheme extends for 8.1km from Brynmawr in the Westto Gilwern in the East, and includes the construction of 14
major structures, over 12.5km of various types of retaining
walls as well as excavation of over 1.2 million m3 ofearthworks. All this was done through on a narrow rockgorge with a river on one side while maintaining current
traffic flows on the existing route.
The main purpose of the site where two ECO700S in
Super crush mode was to widen the existing roads fromthree to four lanes. Constructing the road retaining wall,

Photo 1.

Narrow working spaceapproximately 717 no. 9.5-12.0m long single PU32 piles
had to be installed into mudstone or sandstone in doublelines from October 2016 to April 2017.
4.1.2. Site condition
Photo 1 shows the narrow working space between
the existing road and the valley. The working width isapproximately 7.0 meters which was the minimal size forthe crawler crane operation. Then, one of the double lines
was on a slope (Photo 2). If the conventional piling
method based on the crawler and drill unit had beenutilized, temporary work (i.e. platform, reclamation)
would have been essential to set the rig on the installationline.
4.1.3. Issues and solutions

Photo 2. Piling on slope

The main issue was to install steel sheet piles into
hard rock mass. Fig. 10-a, 10-b show bore hole logs at thissite. According to the soil investigation report, the upper
made ground included boulders, and it was written that thevalue of unconfined compressive strength (Hereafter,
UCS) of lower mudstone/siltstone is 60.7Mpa, and the
UCS of the lowest Sandstone is 92.9Mpa, meaning
extremely hard ground conditions. 685mm diameter preauger heads were first utilized in the UK, solving this issue.
This type of auger head was developed for rock mass. The
situation of discharging the crushed rocks from thewindow of the casing was shown in Photo 3. Some rocks
crushed by pre-augering may be seen. From this photo, thePhoto 3.

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Arising from the window of casingProceedings of the First International Conference on Press-in Engineering 2018, Kochi

the tunnel. The piling duration was approximately 5months from July to November 2016, using two units forthe pressing-in machines.
4.2.2. Site condition
First of all, this site is located near Tower Bridge incentral London, so the noise and vibration generated bypiling works were to be minimized as much as possible,
due to the city’s strict regulations. Further, the groundconsisted of stiff clay with occasional cobbles whose
converted max SPT N-value is 125 (Fig. 11). In addition,
since the Thames is a tidal river, the projecting length
above the riverbed is approximately 9meters at low tidewhilst the operation is on water at high tide. Solving all
the above requirement, the Press-in Method was adopted

Fig. 10-a Bore hole logs of A465 Heads of the Valleys Road

(Photo 4).

section 2

Fig. 10-b Bore hole logs of A465 Heads of the Valleys Road

Fig. 11

Bore hole log of Chambers wharf

section 2

Note that two service cranes per unit were utilized:
4.2. Case study 2: Thames Tideway tunnel -east-

one on land to feed a double Z pile to the pressing machine

4.2.1. Summary of the Site
The Thames Tideway Tunnel is an under-whilst the other one on a pontoon to support the Pile auger,
due to the installation of 22.6m long double Z piles.

construction 25 km tunnel running mostly under the tidal
section of the Thames through central London, which will
provide capture, storage and conveyance of almost all the

4.2.3. Issues and Solutions
In this project, the construction duration including

combined raw sewage and rainwater discharges thatthe piling work had to be minimized as much as possible.

currently overflow into the river.

Hence, the following measures were adopted.

At Chambers wharf, which is one of the site of this・Installation of double Z piles

huge project, two units of Super crush SCZ676WMG were・

Piling by two units

utilized to install 321 no. 17.7-22.6m long double AZ36-

・

700N piles to build twin sheet pile cofferdams for the

Use of the auger head with zooming blades
From the view of the pile installation, one of theconstruction of the shaft being utilized as a relay station ofadvantages of double Z piles, the productivity is literally- 546 -

Proceedings of the First International Conference on Press-in Engineering 2018, Kochi“double” that of the installation of single piles. Then, as

5.1. Pile drivability

double Z piles in two rows, inner and outer, could be

Fig. 13-a shows the typical augering areas of 600mm

installed separately (Fig. 12), the duration of the pilingwidth single U piles, whilst Fig. 13-b shows the ones ofwork was dramatically shortened. Note that it might have

1,400mm width double Z piles. It may be seen that thetaken 20 months if one pressing-in machine (instead of

580mm diameter augering areas of U piles covers thetwo) for single piles (instead of double) had been utilized.

whole section. On the other hand, 980mm diameter

Also, another way to improve productivity is toaugering areas of the double Z piles don’t cover the wholeutilize the auger head with zooming blades. As described

section. Since their pile drivability is logically improvedin 3.2., an auger head replacement shall be requiredby the reduction of their toe resistance, single U piles

between the pre-augering and simultaneous augering.

should be considered to be superior to double Z piles,

However, it is not necessary if using the auger head withparticularly into hard rocks and buried obstructions. Notezooming blades. Usually, it takes approximately 20that stiff and very stiff ground condition should be nominutes per pile to change auger heads, which could be

problem for double Z piles based on the case studies such

cut from the piling work.

as the Thames Tideway tunnel.
5.2. Horizontal response of wall
While installing double Z piles, most augering takes
place on the in-pan side, meaning that the ground
disturbance on the out-pan side, which is also the passive
side, of double Z piles could actually be minimized.
Piling Direction

226
290

226
290

CL

580

CL

Photo 4. Press-in operation on water580

approx. 70

Max. Augering Area ƒÓ
580 mm dia

600

approx. 70

Max. Augering Area ƒÓ
580 mm dia

600
Piling Direction

Fig. 13-a 580mm dia. augering area for single U piles

CL
CL

The 2nd unit

499

249.5 249.5

The 1 unit

Max. Augering Area ƒÓ
950 mm dia
As the simultaneously Augering Area

Max. Augering
Area ƒÓ
9Z50piles
mm diawith Double
As the simultaneously Augering Area
with Double Z piles

249.5 249.5

1400

499

1400

st

approx. 100 mm
approx. 100 mm

Piling Direction

Piling Direction

Fig. 13-b 980mm dia. augering area for double Z piles
Fig. 12

Two units working

Note: The augering area is shown by a blue dashed line
in each drawing.

5. Comparison of installation of single U piles anddouble Z piles
Below, the pros and cons of the installation of bothThen, according to the Euro code 3 part 5 in BSI

single U and double Z piles in the Press-in operation

British Standards (2007) : piling , reduction factorsfor βassisted with augering will be summarized.

shall be applied to U piles due to the possible lack of shear- 547 -

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

siltstones with 92.9Mpa in UCS.

force transmission at the interlocks (Table 3). The valuesof β of single and uncrimped piles in the table is 0.40 to2.

Double Z piles installed by the Press-in assisted with

0.80 subject to the number of structural support levels andaugering should be more effective to wall stiffness

ground conditions, which means the wall stiffness may be

due to the augering on passive side and reduction
factor β specified in Euro code 3 part 5.

reduced by half. In contrast, no reduction is required in
sectional properties of Z piles because interlocks are

3.

The workability of the operation to install single U

located at the far edge of the wall, which means that thepiles should be better as its construction plant isshear force does not occur in the interlocks.

relatively small. It means single U piles can be more
applicable to narrow working conditions.

Table 3.

Reduction factors for U shaped sheet piles

Since the Press-in Method assisted with augering wasdeveloped in 1997 in Japan, this piling technique has
spread all over the world. I hope this paper will be usefulfor someone wishing to understand its characteristics.
7. Acknowledgements
Based on the above mentioned two reasons, the wall

The authors are grateful to Mr Simon King and Mr

constructed of double Z piles should show stiffer response

Andy King of Ivor King (Civil Engineering Contractors)

than that of single U piles.

Ltd and Mr Robert Law of AGD Equipment Limited forthe collaboration with GIKEN Europe B.V in the UK and5.3. Workability in narrow space
Essentially, construction plants become larger andchecking materials used to write this paper.

sections of steel sheet piles become bigger due to theReferences
International Press-in Association. 2016. Press inlength and weight of steel sheet piles. For instance, one
50ton crawler crane should be enough to lift one 12.0m
long single PU32 piles whose weight is 1.37tons, whilst

retaining structures: a handbook.
GIKEN LTD. 2018. Hard Ground Press-in Method Silent

one 100ton crawler crane should be necessary to lift one
22.6m double AZ36-700N pile whose weight is 5.36tons.

Piler ECO400S Techniqueal Brochure.
GIKEN LTD. 2016. Silent Piler Silent Piler ECO700S/

Thus, as described in table 1 and 2, the pressing-in

1400S Brochure.

machine for single U piles is bigger and heavier than the

GIKEN LTD. 2008. Silent Piling Piling Technologes 2008.

one for double Z piles.

Constructing Excellence in Wales. 2017. Design stage

From this point of view, single U piles should becase study A465 Heads of the Valleys Section 2

preferable in narrow spaces where conventional pile

Gilwern to Brynmawr:

drivers could not be set.

http://www.cewales.org.uk/files/2114/9812/2528/A4
65_Heads_of_the_Valleys_Section_2_Gilwern_to_
Brynmawr_Design_Stage.pdf.

6. Concluding remarks
This report introduces Press-in assisted with augering

Tideway. 2018. The Web site of the Thames Tideway

based on two types of steel sheet piles and two case studies
in the UK. Also, the characteristics of the installation of

Tunnel: https://www.tideway.london/.
ArcelorMittal. 2016. Piling Handbook 9th edition. ISBN

single U and double Z piles are described. Based on them,
the following conclusions can be drawn:
1.

978-99959-0-194-3.
BSI British Standards. 2007. UK National Annex to

The Press-in operation with augering can be

Eurocode 3: Design of steel structures – Part 5: Piling.

applicable for stiff to hard ground conditions.

NA to BS EN 1993-5:2007.

Particularly, the augering of single U piles should be
more effective in hard ground conditions such as- 548 -