application of ssp-basement.pdf

7/23/2019 Application of SSP-Basement.pdf

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Unauthorized reproduction and distribution prohibited. The information contained in this document is for general information purposed only. No warranty is expressed or implied. Anyonewish to apply this information shall satisfy themselves of its validity relatives to the applicable conditions. All the technical data in this document is liable to change without notice.

Application of Sheet Piling


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Application of Sheet Piling

Waterfront Structures

Power Plant

Basement Construction


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Application of Sheet Piling Basement Construction

Function: To provide effective temporary / permanent retaining wall system

for deep excavationOverview of basement structure:


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Function: To provide effective temporary / permanent retaining wall system for

deep excavationDesign Considerations / Requirements:

1) To consider soi l heaving at base, design sheet piling length to control.

2) To prevent water piping through base during excavation. Thus water permeability cut off by

length of sheet piling.

3) Likely to have adjacent building / structures. Thus need vibration / noise control for

installation by choosing appropriate machine (vibratory & press in).

Impact of dr iving

load dissipating

through ground to

adjacent buildingVibratory Pil ing Machine Press in Silent Piler


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Function: To provide effective temporary / permanent retaining wall system for

deep excavationDesign Considerations / Requirements:

Addit ional surcharge on top of wall as

water retention in tension crack area.

Tight horizontal retaining wall deflection & vertical soil movement control. The following

tolerances typically apply:

Permanent: Horizontal wall deflection < 50mm

Vertical soil movement < 25mm

Temporary: Horizontal wall deflection < 100mm

Water ponding at

tension cracking area

will impose additional

load to retaining wall


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Benefit of permanent basement sheet piling wall (by Top Down Construction

Method): In additional to resist lateral pressure, sheet piles can be designed to takesvertical / axial load to reduce foundation cost significantly.

Save construction time tremendously because the superstructure and

substructure construction can be carried out concurrently at the same time,eliminated the need for temporary support system with struts

No extraction of temporary sheet pi le is required. Immediate watersealing (no lowering of ground water, minimum disturbance to

adjacent building, services, roads, etc)

No addit ional secondary interior wall required.

Max use of space.


Slab to provide anchoringforce for sheet piling

support

Sheet piling to

take vertical loads


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Method Statement Top Down Method


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Method Statement Top Down Method


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Design Considerations / Requirements permanent basement

sheet piling wall (by Top Down Construction Method): Control water seepage through interlocks of sheet piling.

Thus wider sheet piling will has higher water resistance

(less interlocks per length of wall).


Sheet Pile

A

A

B

B

" Headed Studs

4" Long At 12" O/CStaggered Along Face

of Sheet Pile

Section A-A

Durability of sheet piling in embedded soil side & exposed side. Retaining wallservice life is long term, > 50 years to international standards.

Connections details of permanent sheet piling wall to slab / beam can becalculated based on loading from structure.


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Benefit of temporary basement sheet piling wall (by Top Down Construction

Method): Reusable sheet piling material to save construction cost on retaining wall

construction.

Easy handling & fast installation of sheet piling wall.

Ease of construction for complex basement layout.



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Design Considerations / Requirements temporary basement sheet piling wall:

For excavation > 4m, need to consider strutting system / anchoring as intermediatesupport.

Connection details can beprovided by technical assistance

from Oriental Sheet Piling


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Durability Concern

Rate of Corrosion of Steel as per international standards:

Underground soil conditions / embedded in soil

Exposed atmospheric



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Rate of Corrosion of Steel in underground soil condi tions (Arcelor Piling Handbook, 8th

Edit ion, Jan 2005)

-Underground corrosion of steel sheet piles has been studied extensively, concluded that the

underground corrosion of steel piles driven into undisturbed soils is negligible.

-Evaluations of piles extracted from UK sites, ranging from canal and river embankmentsthrough harbours and beaches to a chemical slurry lagoon containing acid liquors (pH 2.8),

also confirm negligible underground corrosion losses.

-A further evaluation in Japan of test piles driven into natural soils at ten locations which

were considered to be corrosive gave a maximum corrosion rate of 0.015mm/side per

year after ten years exposure.-It is concluded that in natural, undisturbed soils steel pile corrosion is very slight, for thepurpose of calculations, a maximum corrosion rate of 0.012mm/side per year can be

used. This losses of steel thickness can be accommodate by choosing slightly higher section

of steel sheet piles in retaining wall design.

Durability Concern



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Rate of Corrosion of Steel in underground soil conditions (Recommendations of theCommittee for Waterfront Structures Harbours and Waterways EAU 1996):

-The anticipated decrease in thickness on both sides of steel sheet piling embedded in

natural soils is negligib le with 0.01mm/year.

-The same corrosion load applies in the case of necessary backfilling immediately behindthe piling when sandy soil is placed in such a way that the troughs of the piling are also

thoroughly embedded.

-Highly aggressive soils should be kept away from the surface of the sheet piling as far as

possible. Such soils include among others humus soil and carbonaceous soils, for example

waste washings.-Similarly, contaminated surface water and leachate should be avoided on the backside of

the sheet piling which promote the growth of bacteria aggressive to steel.

Durability Concern



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The effective life of steel sheet piles unpainted or unprotected, prEN 1993-5: 2002, Design of Steelstructure Part 5: Piling, Table 4.1 Losses of thickness (mm) due to corrosion for piles and sheet pilesin soils, with or without groundwater.

The reduction of thickness of steel can be considered in design by choosing slightly higher steel section

as per the anticipated site conditions.

5.754.503.252.000.50Non-compacted and aggressive fills (ashes, slag,)

2.201.701.200.700.18Non-compacted and non-aggressive fills (clay,schist, sand, silt,)

3.252.501.751.000.20Aggressive natural soils (swamp, marsh, peat,)

3.002.251.500.750.15Polluted natural soils and industrial grounds

1.200.900.600.300.00Undisturbed natural soils (sand, silt, clay, schist,)

100 yrs75 yrs50 yrs25 yrs5 yrsRequired design working life

Durability Concern



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Rate of Corrosion of Steel in atmospheric conditions (Arcelor Piling Handbook, 8th

Edit ion, Jan 2005)

-In such cases bare steel will corrode in the atmosphere at a rate which depends upon

the site environment. In order of increasing corrosivity, this can be broadly classified as

rural, urban or industrial. Similarly, piling at coastal sites may be subject to a marineatmospheric environment.

-prEN 1993-5: 2002, Design of Steel Structures Part 5: Piling, indicates that the

atmospheric corrosion of steel averages approximately 0.01mm / side per yearand

this value can be used for most atmospheric environments.

-However, higher corrosion rates may be experienced in close proximity to the sea orwhen pollution produces very aggressive mirolimates.

Durability Concern



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Rate of Corrosion of Steel in atmospheric conditions (Recommendations of the

Committee for Waterfront Structures Harbours and Waterways EAU 1996):

-Atmospheric corrosion, i.e. corrosion above the splashing water zone is generallylow.

-In case of water structures, it is practically negligible with a corrosion speed ofaprox. 0.01mm / year.

Durability Concern



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Methods of increasing the effective life of a structure can considered the below:

Use of a heavier section

Use of a high yield steel at mild steel stress levels

Applying a protective coating. As per Recommendations of the Committee for

Waterfront Structures Harbours and Waterways EAU 1996, according to availableexperience, coatings can delay the start of corrosion by more than 20 years.

Suggested coating system (Arcelor Piling Handbook, Jan 2005).

Sand blasting to a standard degree of purity of SA 2.5,

Zinc epoxy primer,

Re-coatable epoxy intermediate coating

Aliphatic polyurethane topcoat

Nominal dry film thickness of the system 240 um.

Durability Concern



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Impervious Steel Sheet Pile Wall

Table 2.2, BS 8102: 1990, The protection of structures against water from the ground.

Totally dry environmentArchives and storages requiring controlledenvironment

4

Dry environmentVentilated residential & working areas

including offices, restaurants etc.; leisurecentres

3

No water penetration but moisturevapour tolerable

Workshops & plant rooms requiring drierenvironment; retail storage areas

2

Some seepage and damp patches

tolerable

Car parking; plant rooms (excluding electrical

equipment); workshops

1

Performance LevelBasement UsageBasement

grade



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Unauthorized reproduction and distribution prohibited. The information contained in this document is for general information purposed only. No warranty is expressed or implied. Anyone

wish to apply this information shall satisfy themselves of its validity relatives to the applicable conditions. All the technical data in this document is liable to change without notice.

Design consideration of water seeping through interlock (joints)of sheet pi le walls:

-Basic Darcys Law applied where v = K * i where v is filtration

rate, K is coefficient of permeability and i is hydraulic gradient.

-For joints of sheet piles wall,q(z) = * p(z) / , where

q(z): the discharge per unit of the joint length at level z, (m3/s/m)

p(z): the pressure drop at level z, (kPa)

: the inverse joint resistance, (m/s)

: unit weight of water (kN/m3)

Refer brochure for more details and examples calculations




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Unauthorized reproduction and distribution prohibited. The information contained in this document is for general information purposed only. No warranty is expressed or implied. Anyone

wish to apply this information shall satisfy themselves of its validity relatives to the applicable conditions. All the technical data in this document is liable to change without notice.

Method of sealing steel sheet pile wall: Bituminous product (hot applied) for applications where average performance ( =

6 x 10-8 m/s) is required in respect of watertightness

Water swelling product (cold applied) for high performance applications ( = 6 x10-8 m/s).



Non-structural welding of sheet pile interlocks. It is

possible to create a seal by applying a simple fillet

weld across the joint as illustrated.

1. Filling the free interlock 2. Filling the threaded interlocks

considering the hydrostatic pressure side

application of ssp-basement.pdf

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