Edition: May 2008
Specification: Part S20 Reinforced Soil Structures
PART S20
REINFORCED SOIL STRUCTURES
CONTENTS
1.
2.
3.
4.
5.
6.
7.
8.
General
Design
Materials
Construction
Miscellaneous
Hold Points
Test Procedures
Verification Requirements
1.
GENERAL
This Part specifies the requirements for the supply of materials and the construction of Reinforced Soil Structures. It
also includes design requirements where the Principal has not provided a detailed design of the wall.
Reinforced Soil Structures shall consist of a composite system of compacted select backfill and reinforcing material
with precast concrete wall facing.
Documents referenced in this Part are listed below:
AS 1289
Methods of Testing Soils for Engineering Purposes
AS 1554
Structural Steel Welding Code
AS 3678
Hot Rolled Structural Steel Plates, Floor Plates and Slabs
AS 3679
Hot Rolled Structural Steel Bars and Section
AS 4671
Steel Reinforcing Materials
AS 4680
Hot-dip Galvanized (Zinc) Coatings on Fabricated Ferrous Articles
AS 5100
Bridge Design
2.
DESIGN
2.1
Preliminary Design
The following information shall be included in the Contractor’s Preliminary Design:
(a)
name of proposed proprietary system;
(b)
preliminary drawings describing the proposed reinforced soil block geometry, drainage provision, soil
reinforcement arrangement and wall facing arrangement and surface finish;
(c)
type and source of select fill including particle grading;
(d)
name and qualifications of Proof Engineer; and
(e)
preliminary calculations to demonstrate feasibility of the system.
2.2
Final Design
The following information shall be submitted by the Contractor within 4 weeks of the Date of Acceptance of Tender
and not less than 6 weeks prior to manufacture of facing panels:
(a)
final design calculations, detailed specification and final construction drawings including verification and
certification by the Proof Engineer; and
(b)
sampling and test plan for materials to be incorporated in the works and demonstrating compliance with
required standards, including shear strength and coefficient of friction for select fill.
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Specification: Part S20 Reinforced Soil Structures
The design shall be verified and certified by a Proof Engineer. The Proof Engineer shall be:
(a)
independent of the original designer;
(b)
a Professional Engineer with qualifications admitting to Corporate Membership of the Institution of
Engineers; and
(c)
experienced in this form of design and construction.
Provision of the Final Design Documents and accompanying Proof Engineering Certificate shall constitute a HOLD
POINT.
2.3
Design Requirements
Unless specified otherwise, all design shall be undertaken in accordance with the following documents:
(a)
DPTI "Structural and Geotechnical Section Drafting Guidelines" provided in "Consultant Package" on
CD ROM and AS 1100 "Technical Drawing"
(b)
Australia Standard AS 5100 "Bridge Design"
(c)
Australian Standard AS 1170.2 – Part 2: "Wind Loads"
(d)
Australian Standard AS 4678 – "Earth Retaining Structures"
(e)
Australian Standard AS 2312 – "Guide to the Protection of Structural Steel against Corrosion by the use of
Protective Coatings"
(f)
AS 1428 "Design for Access and Mobility"
(g)
AUSTROADS Guide to Traffic Engineering Practices, Part 13 "Pedestrians and Disabled Road Users"
(h)
AUSTROADS Guide to Traffic Engineering Practices, Part 14 "Bicycles".
Structures shall be designed for a minimum life of 100 years.
The design loadings transferred from bridge abutments to the structures will be specified on the Drawings or in the
Contract Specific Requirements. The live loading from bridge approach roads and the vertical and lateral loads
from the earthwork shall be taken into account in the design.
The structure shall satisfy the stability requirements of the AS 5100 for earth retaining structures.
Allowable bearing pressures and settlements on the founding material under the reinforced soil block are contained
in the Contract Specific Requirements.
Drainage provisions shall be made in the backfill where necessary to intercept or divert groundwater and surface
water to prevent scour or the development of hydrostatic pressure behind facing panels. The design shall incorporate
provisions to prevent saturation of the backfill in the event of a leaking water main. The drawings shall clearly show
all drainage provisions.
For straight walls, the design shall provide for a 1 in 40 slope on the vertical wall face.
If the design is to cater for future extensions (refer to the Contract Specific Requirements or the drawings), the
design shall allow for both initial and future configurations. For walls which are to be extended in height, initially
placed reinforcement and facing panels shall be designed to resist the future height wall and any surcharge without
adjustment (except for removal of non-standard capping panels). For walls that are to be extended laterally, the
extension shall be able to be constructed without disturbing reinforcing straps that are to remain in place.
2.4
Format of Design and Documentation
The design model shall be in a plane coordinate system based on the station coordinates of the original terrain model
as supplied by the Principal. The Design and Documentation shall be supplied in the following formats:
(a)
Electronic copy of drawings in pdf, dwg and dwf format, with a file name in accordance with the protocol
supplied by the Principal;
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(b)
Specification: Part S20 Reinforced Soil Structures
All Drawings shall be drawn in modelspace and presented in view ports in paperspace;
Drawings shall comply with the DPTI: Road Design Standards and Guidelines, available from the following internet
site: http://www.dpti.sa.gov.au/standards.
Any reference to Design Software in the Contract shall be a reference to the version current at the time of Tender.
The Contractor shall advise the Principal which existing DPTI drawings are superseded and which are to be
amended as a result of the new design and modify the drawings accordingly. The Contractor shall complete a form,
provided by the Principal, that tracks the checking and approval status of each drawing.
2.5
Design Records
The Contractor shall provide following records:
Drawings
A complete set of drawings in the formats described in Clause 2.4 “Format of Design and Documentation”.
The drawings shall be to a level of detail such that no further production of drawings will be required to assist
construction. Any reference to any standards or ancillary drawing on any sheet shall have the reference to its
sheet number.
Reports
The final design report shall include:
2.6
(a)
A full set of design calculations, incorporating calculations and determinations for all elements, appropriate
sketches and details; and
(b)
Design summary.
As Constructed Drawings
Whenever work is constructed that is at variance with the drawings, the Contractor shall modify the final drawings to
show what was actually constructed. Within 3 working days of the varied work commencing, the Contractor shall
provide notification of the extent of varied work and the date by which the drawings showing what was actually
constructed will be submitted. Within 6 weeks of the Date of Practical Completion, the Contractor shall provide any
outstanding copies of drawings showing what was actually constructed.
3.
MATERIALS
3.1
Wall Facings
Wall facing panels shall be of incremental height, precast reinforced concrete, manufactured in accordance with
Division CC "Concrete". The minimum concrete grade shall be S32. Steel reinforcement shall be a minimum of
450 mm2 per metre in each of two directions at right angles to each other and located at mid-depth of the panel
thickness. Wall facing panels shall be positively interconnected to prevent relative displacement normal to the wall
face.
3.2
Joint Fillers
Joint fillers between wall facing panels shall be composed of durable inert material resistant to attack from the soil
material and the atmosphere.
Joint fillers shall be provided to allow for joint rotation without spalling of concrete edges and to prevent loss of
fines from the backfill material and staining of the panel faces.
3.3
Soil Reinforcing
Reinforcing strips or grids and their connections, which are attached to the wall facing panels and embedded in the
fill, shall be fabricated from approved reinforcing products.
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Specification: Part S20 Reinforced Soil Structures
Such products shall be demonstrated by the supplier as being sufficiently strong, stiff, stable and durable to satisfy
the performance and design requirements of major reinforced soil structures and this Specification with a minimum
of 10 years data from laboratory and site applications in representative conditions.
Steel reinforcing shall comply with AS 3679, with a minimum base metal thickness of 5 mm and hot dip galvanized
after fabrication in accordance with AS 4680 with a minimum average coating thickness equivalent to 600 grams per
square metre.
Steel mesh shall comply with AS 4671 and hot dip galvanized after fabrication with zinc to AS 4680 with a
minimum average coating thickness equivalent to 600 grams per square metre.
Synthetic material shall comply with a British Board of Agreement Certificate and demonstrated by testing in a
NATA accredited laboratory to satisfy the performance and design requirements of this Specification.
3.4
Connections
Materials connecting the wall facing panels with the reinforcing elements shall be electrolytically compatible to
ensure that corrosion will not be promoted through the use of dissimilar metals. All materials forming connections
shall be adequately protected for the in-situ conditions, consistent with the protection provided for adjacent
components and for the defined structure life.
3.5
Handling Transportation and Storage
Handling transportation and storage of prefabricated structure components shall not cause any damage or
deterioration. Synthetic reinforcement elements susceptible to UV degradation and chemical attack shall be
protected.
3.6
Backfill
Select backfill shall comply with the requirements of the designer and have a particle size distribution, shear strength
and co-efficient of friction value to ensure the design parameters are achieved.
If the backfill is in contact with galvanized steel components, it shall comply with the properties specified in
Clause 8 "Verification Requirements". Pulverised fuel ash (PFA) shall not be used as select backfill.
4.
CONSTRUCTION
4.1
Levelling Pads
Levelling pads shall be cast from Grade N20 concrete to the lines levels and dimensions shown on the drawings,
within the following tolerances:
Plan dimension
- 5 mm
Thickness
-10 mm
Reduced level of top surface of footing
- 5 mm to + 5 mm
Maximum variation of top surface from a 3 m straight edge
5 mm.
The pads shall be cured for a minimum of 24 hours before placement of wall panels.
4.2
Panel Erection
Panels shall only be handled and lift by the means of the lifting device or other method specified by the designer.
Each wall facing panel shall be supported immediately after erection and until the abutting fill material has been
placed and compacted. Panels shall be erected without disturbance, damage or distortion of reinforcing strips or
panels.
The Contractor shall set out an offset line in front of and parallel to each Reinforced Earth wall levelling pad. On
completion of each row of panels and before commencing the next row, the Contractor shall submit details of the
final position of the top and bottom of each panel.
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4.3
Specification: Part S20 Reinforced Soil Structures
Placement of Filling
Fill shall be dumped on to the reinforcing strips so that the toe of the fill pile is approximately 1.5 m from the panels.
The material shall be pushed parallel to the panels and spread toward the panels and toward the free end of the strips.
Fill placement shall follow the erection of each run of panels. At each reinforcing strip level, fill shall be compacted
before placing and bolting strips. Reinforcing strips shall be placed as shown on the Drawings.
At the end of each days operations, the Contractor shall shape the top of fill so as to direct run off of rainwater away
from the wall face.
4.4
Compaction of Filling
Fill shall be placed in layers of between 100 mm and 200 mm compacted thickness and the properties comply with
those specified in Clause 8 "Verification Requirements". The location of tests shall be selected by the Contractor for
each lot on a stratified random basis.
The minimum frequency of compaction testing shall be the greater of:
(a)
6 tests per 500 mm thickness of fill placed, and
(b)
6 tests per 50 cubic metres.
Heavy earthmoving and compaction equipment (in excess of 2 t Gross Vehicle Mass) shall be kept at least 1.5 m
away from the back of the wall. Tracked machines or vehicles shall not be operated on top of reinforcing elements
until the elements are covered by at least 150 mm of fill material. Sheepsfoot rollers shall not be used for
compaction of fill material.
4.5
Tolerances
The finished wall shall comply with the tolerances in Table 4.5.
TABLE 4.5
PROPERTY
ACCEPTANCE LIMITS
Departure from plan position shown on the Drawings at base of wall
<  15 mm
Relative displacement of adjoining smooth panel faces measured normal to
face of wall
<  15 mm
Local deviation of the wall face measured at any location with a 3 m straight
edge
< 15 mm
Overall vertical tolerance of the exposed wall face
< 5 mm per metre of wall height
Reduced levels on the wall
<  20 mm
Variation in exposed gap width between panels
< 5 mm per metre length.
The Contractor shall provide a Survey Certificate; vide Part CH30 "Survey”, demonstrating that the wall complies
with the tolerances specified by this Part.
5.
MISCELLANEOUS
5.1
Spoon Drains
Spoon drains shall be provided at the top of the walls to collect drainage from adjacent batter slopes and shall
discharge to collection pits with outlets to the drainage system.
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5.2
Specification: Part S20 Reinforced Soil Structures
Safety Fences
Vertical drops greater than 1.0 m created by construction of the wall shall be protected by safety fences along the top
of the wall. The fence shall be 1.2 m high with a top and bottom rail of galvanized steel tube and faced with steel
chain mesh unless otherwise specified on the Drawings.
6.
HOLD POINTS
The following is a summary of Hold Points referenced in this Part:
CLAUSE
REF.
2.2
7.
RESPONSE
TIME
HOLD POINT
Provision of Final Design
10 Working Days
TEST PROCEDURES
The Contractor shall use the following test procedures (refer http://www.dpti.sa.gov.au/contractor_documents) to
verify conformance with the Specification:
TEST
TEST PROCEDURE
Site Selection by Stratified Random Technique
TP 061
Dry Density Ratio
TP 320
Ph, Resistivity, SO4 Content
AS 1289
8.
VERIFICATION REQUIREMENTS
The Contractor shall supply written verification that the following requirements have been complied with and supply
the verification with the lot package. Refer to Clause 2 "Design" for verification documentation if design is included
in this Contract.
CLAUSE
REF.
SUBJECT
PROPERTY
TEST
PROCEDURE
TEST
FREQUENCY
ACCEPTANCE
LIMITS
3.1
Concrete
properties
Refer
Division CC
Refer Division CC
Refer
Division CC
Refer Division CC
3.3
Steel Soil
Reinforcing
Refer AS 3679
or AS 4671
Refer AS 3679 or
AS 4671
Refer AS 3679
or AS 4671
Refer AS 3679 or
AS 4671
3.3
Synthetic
Soil
Reinforcing
Refer British
Board of
Agreement
Certificate
Refer British Board
of Agreement
Certificate
Refer British
Board of
Agreement
Certificate
Refer British Board of
Agreement Certificate
3.6
Select
backfill
Gradings and
Soil Constants
Refer Part R10 or
S10
Refer Part R10
or S10
Refer Part R10 or S10
Shear Strength
& Coefficient of
Friction
As specified by
designer
As specified by
designer
As specified by
designer
pH
AS 1289.4.3.1
1 test per 400
cubic metres
between 5 - 10
3.6
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backfill in
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CLAUSE
REF.
SUBJECT
contact with
steel when
structure is
not subject
to inundation
3.6
4
Specification: Part S20 Reinforced Soil Structures
PROPERTY
Resistivity
TEST
PROCEDURE
AS 1289.4.4.1
TEST
FREQUENCY
ACCEPTANCE
LIMITS
1 test per 400
cubic metres
> 5 000 (ohm.cm).
If in range 1 000 to
5 000, it will be
accepted if SO4 is
satisfactory
SO4 content
(only required if
resistivity in
range 1 000 to
5 000)
AS 1289.4.2.1
1 test per 400
cubic metres
< 1 000 (mg/kg)
Select
backfill in
contact with
steel when
structure is
subject to
inundation
pH
AS 1289.4.3.1
1 test per 400
cubic metres
between 5 – 10
Resistivity
AS 1289.4.4.1
1 test per 400
cubic metres
> 3 000 (ohm.cm).
SO4 content
AS 1289.4.2.1
1 test per 500
cubic metres
< 500 (mg/kg)
Wall
Construction
Backfill
Compaction
TP 320
Refer Clause 5.4
Not less than 95%.
Position of
Levelling Pads
Survey Certificate in
accordance with
Part CH30 "Survey"
Refer Part CH30
Refer Clause 5.1
"Levelling Pads"
Panel Position at
completion of
each row
Survey Certificate in
accordance with
Part CH30 "Survey"
Refer Part CH30
Refer Table 5.5
Panel Position at
completion of
wall
Survey Certificate in
accordance with
Part CH30 "Survey"
Refer Part CH30
Refer Table 5.5
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