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

Design and Installation of a Permanent Sheet Pile basement for the Manly
Twenty95 Development
Davide CANTALI
Senior Sales Engineer , J Steel Australasia Pty Ltd
Email: dcantali@jsteel.com.au

Taro ITO
Project Manager, J Steel Australasia Pty Ltd
Email: tito@jsteel.com.au

ABSTRACT
Manly Twenty95 project is a luxury 6 story (24 apartment) residential development currently under construction in
Sydney Australia. J Steel Engineering had been constructed the permanent 4 level basement for an integral automatedcarpark storage facility for this development in March 2018 using the ECO600S Silent Piler. Approximately 100m ofsheet pile wall was required for the basement structure. 21m long, 600mm wide hot rolled U piles were installed with
the Super Crush system in dense to very dense sands to support excavation depths of up to 12.5m. The bottom-up
technique with temporary propping was adopted by the builder. This paper identifies and discuss the design andconstruction challenges for the permanent sheet pile basement, including; supporting large vertical column loads on thesheet pile wall, durability aspects for providing a life beyond 50 years, and interfacing with temporary and permanent
lateral supports. In addition, the paper emphasizes interesting aspects related to the installation of the sheet pile system,including use of the Super Crush for installing long sheet piles and problem solving of any other issues that arised
during the works.
Key words: Giken ECO600S, Permanent Sheet Pile Basement, Design, Axial load

1. Outline of the project1.1. Place
The project site is located on the corner of the busy
intersection of Belgrave Street and Sydney Road in Manly,Sydney, NSW Australia – a 5min. walk from the surfbeach and opposite to Manly Oval. Adjacent to the site is
an existing telecommunications exchange and a heritage
listed sandstone church (Fig. 1).

Fig. 1- 563 -Site location

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

1.2. Background and objectives of the project
The project site is a small congested site

Table 1.

2

approximately 1000m in area. Grocon are developing theTop ofsite into 4 levels of 1, 2 & 3 bedroom luxury apartments inunit

addition to some commercial and retail space. To service(RL mthe building, a 4 level automated carpark within aIdealised geotechnical design profile
Cone

MaterialresistanceqcAHD)

Consistency(MPa)permanent basement will be constructed. A maximum

5.50

Sand (Fill)

10

Variable

excavation depth of ~12.5m is required to construct the4.50

Sand

5Loosecarpark.

1.00

Sand

10

Medium Dense-11.70

Sand28Dense

2. Structural type and piling method

Dense

2.1. Site condition
The site is within the busy commercial/residential
precinct of Manly and was formerly used as apark/carpark (Photo 1).
Due to the restricted site space and concerns
regarding noise within the retail area and vibration
damaging heritage listed buildings, suitable retaining wall
systems were carefully considered.

Photo 1.

Site Image

2.2. Ground condition
The site is underlain by Quaternary sediments
comprising medium to fine grained marine sands. In thispartofManly,

thesediments

typically

overlie

Hawkesbury Sandstone at depths of 36 m to 39 m (Table
1 and Fig. 2).
The groundwater table is high, about 4m below
existing ground surface (+5.5m AHD).
A number of CPT’s and sampled boreholes werecompleted on site indicating loose to medium dense sandbecoming dense then very dense.

Fig. 2- 564 -Bore Hole DatatoVeryProceedings of the First International Conference on Press-in Engineering 2018, Kochi

The conventional sheet piles installation method

2.3. Structural type & design
The project required a permanent basement wall forusing a vibration hammer was NOT recommended fora design life of 50 years. The basement would be

the use on this site as there were movement sensitive

constructed bottom up and required a maximum 12.5m

structures adjacent to the excavation. We proposed theexcavation. In the temporary case, the walls would bePress-in Piling method using our ECO600S with thesupported by temporary anchoring and bracing, and by

design described below.

concrete slabs at each of the basement slab levels in thepermanent scenario.

A PU22 pile section, supplied as 600mm wide U
piles, was determined as the preferred section to support

The initial Geotechnical report provided by theclient suggested for the retaining wall system either of;

the earth and water pressures in the temporary andpermanent case (Fig. 3).

1) A secant pile wall comprising interlocking
Continuous Flight Auger (CFA) piles or CFA piles with
jet grouted columns between the piles.
2) Soil mixed wall systems constructed using
specialised equipment to either blend cement with thein-situ soils to create a soil-cement mix.

Fig. 3 PU22 pile properties- 565 -

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

As per the client design requirement the walls also

permanent columns supporting the superstructure above.

had to support permanent surcharge load from theThe maximum factored column loads of up toadjacent pedestrian footpaths and roadways (up to2141kN were supported on 2, 3 or 4 U piles. Fig. 520kPa) as well as temporary construction load from theshows column loading. Also the sheet pile/wall wasplant, equipment and materials (up to 50kPa).

required to provide cut-off to limit groundwater flow into

Fig. 4 section view shows a typical design

the excavation.

arrangement for the permanent case.
In addition to supporting earth and water pressures,the walls were required to support axial load fromFig. 4 PU22 pile properties- 566 -Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

Fig. 5Column Loadings

jetting operation, and a possible disturbance to nearby

2.4. Durability
In accordance with the Australian Standard AS2159,
the site was classified as non-aggressive to steel piling. A

ground/ structure by high pressure jetting, J Steelproposed the press-in with augering with ECO 600S.

corrosion allowance of 0.025mm/yr was allowed on thefront and back faces of the wall, reducing thickness by

3. Press-in piling

1.25mm per side over 50 years (2.5mm overall). In

3.1. Layout

addition, on the inside within the basement excavation,

The layout of the sheet piles can be seen in Fig. 6.

the sheet piles will be painted and maintained for a 25

The sheet pile length varies depending on the excavation

year life.

depth.

The appropriate reductions in section modulus andmoment of inertia were determined and applied in thedesign calculation to confirm satisfactory structural
performance at end of life.
2.5. Piling method
The geotechnical report stipulated to conduct further
testing to determine the appropriate disposal options ofground water as it detected hydrocarbons within thesamples collected from the monitoring well.
Initially the press-in with water jetting was planned.
However, considering the counter measure against
possibly contaminated groundwater collected from the- 567 -Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

3.3.2. Site personnel
The site personnel to execute the works are listed
below;

Fig. 6-

T. Ito – Engineer (J Steel)-T. Ueta – Operation of ECO 600S (Giken)-

M. Machida – Leading hand (Giken)-

K. Fukumori – Offsider (Giken)-

C. Carde – Supervisor (Keller)-

L. Copley – Welder (Keller)-

R. Coombes – Offsider (Keller)-

80 Ton Crane Operator (Keller/ WGC)

-30 Ton Crane Operator (Keller/ WGC)

Layout of Sheet Piles

3.2. Productivity
We used 1 no. x press-in machine (ECO 600S) for

3.4. Encountered difficulties

entire project. The outline of our program on the site is

3.4.1. Delay of existing sub-station removal
We mobilised resources on 13/12/2017 based on thedescribed in Table 2;Sub-station located within the site would be removed in aTable 2.

week time. However this did not happen until 27/2/2018.

Outline of Site ProgramThis delay had resulted in significant low productivity
and increase of work load. We were also forced to reduce
our storage area and increased congestions on the site.
The originally planned foot print was as per below Fig. 7.
This was changed drastically due to the existence of theSub-station. Cranes were needed to increase theircapacity to enable to reach longer distance. Sheet piles
were needed to store on top of the existing Telecom
Noticeably, the actual working (piling) day was 34

Building.

out of 60 business days we stayed on the site. The causesof the stand down of our resources will be explained in thenext section.
The maximum length of sheet pile installed within aday was 9 Sheets x 21.0m = 189 m which was recorded on
17-January 2018.
3.3. Resources
3.3.1. Major plant and equipment
The major equipment use on site are listed below;-

1 no. Press-in ECO 600S - Giken/ JSteel-

1 no. 80 ton Crawler Crane - Keller/ WGC-

1 no. 30 ton Crawler Crane - Keller/ WGC-

1 no. 250 cfm Air Compressor - Keller/ Coates-

1 no. 5 ton Excavator - Keller/ Coates

sequence of our piling works. Closing the sheet pile wall

-1 no. Welding Machine – Keller

as a “box” (clutched) required a careful planning.

-1 no. Oxy Cut set – Keller

Closing at a 90 degree corner is a normal practice as it

Fig. 7 Planned Foot Print

The existence of Sub-station also affected theprovides greater flexibility to absorb material and- 568 -Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

construction tolerance. However due to the existence ofexisting cables close to the site boundary had beensub-station we needed to re-plan the piling sequence andidentified and protected.

compromised to close the wall at 45 degree (Number 6 at
Fig. 7), which eventually took us for a few days to close
because of the the limited flexibility compare to a 90
degree corner and the deviation of the wall was morethan what we anticipated.
Moving the Piler from one place to another took
about half a day. The 27m casing auger was required tobe removed and dismantled. Associated plant andequipment need to be re-organised.
Initially we anticipated only twice for moving thePiler. But after we changed the sequence we had to move
5 time which increased 3 movements from the originalplan.
Fig. 8 Piling Platform Level

3.4.2. Piling platform level issue
1m deep x 2m wide trench was to be excavated

3.4.3. Tolerance of sheet pile material

along the perimeter line before we commence the piling

The Fig. 9 shows the comparison between the actual

works. However the client found an existing high voltage

distance and the design distance of sheet pile walls. Ascables along the boundary line and could not create thecan be seen approximately 270mm was lengthened duetrench (Fig. 8).

to extra 5-6mm width of each sheet pile.

The failure to excavate over the boundary resulted
in extending piles for 1m and slower productivity while

Fig. 9These extra lengths were absorbed at the corner
which had greater flexibility.

Tolerance of Sheet Pile Material- 569 -Proceedings of the First International Conference on Press-in Engineering 2018, Kochi

3.4.4. Ground Movement due to Pre-Drilling
As can be seen in the Photo 2 and 3, we observedsome crack and subsidence were caused, possibly by ouraugering works along the perimeter.
The client used plywood and fence posts andexcavated the site about 1m before we commence ourworks (refer to Photo 1).
Patched repair of path was done by the client andfortunately no serious damaged been observed.

Fig. 10
Photo 2.

Contractual Formation

Pedestrian Path 1

4. Concluding remarks
This paper described the outline of the project
including how we carried out the design for the basement
as well as the construction works. We particularly spent a
space for problems we encountered on site which wewould like to share with other members for future use.
5. Acknowledgements
This project would not have been possible without
full support from Giken's personnel from the tender stage
to the completion of the site works. We would like toPhoto 3.

extend our sincere appreciation to all of Giken team.

Pedestrian Path 2

3.4.5. Execution team on site
Fig. 10 shows the contractual formation of theReferences
Australian Standard 2159. 2009. Piling - Design andproject. Although we had engaged with a well-known
specialist contractor, Keller, they had no experience inInstallation, Council of Standards Australia.
DouglasPartners

PtyLtd.

2016.

Geotechnicalpress-in operation. Therefore, we had 3 members from

Investigation, Proposed Residential Development,

Giken including an experienced operator during the85028.00.R.001.Rev1.

course of the project to ensure we provide the best

J Steel. 2017. Design Report – Sheet Pile Wall,performance.

JE-7003-DR-04.
Arcelor Mittal. 2017. Arcelor Mittal Sheet Piling.
Catalogue.

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