CSTR: Part D25 Design – Earthworks for Roads
Edition: November 2014
PART D25
DESIGN – EARTHWORKS FOR ROADS
CONTENTS
1.
2.
3.
4.
5.
6.
1.
General
References
.
.
.
Records
GENERAL
This Part specifies the requirements for the design of earthworks for roads and associated structures. The
requirements of this Part are in addition to those specified in Part R10 "Construction of Earthworks".
2.
REFERENCES
Unless specified otherwise, all design must be undertaken in accordance with the following:
1) DPTI Design Standard: Earthworks for Roads EW100; available from
http://www.dpti.sa.gov.au/standards/roads-all
3.
GENERAL FILL
Unless the Contractor’s design establishes other parameters, at a minimum, General Fill material must comply with
the following:
General Fill – Specified Requirements
Material
Classification
(Refer to CSR
part 210 and 215
for definitions)
Maximum
allowable
Weighted
Plasticity Index
(WPI)
Shrink Swell
Index
Iss (%)
Level of compaction
Range of Placement
Moisture Content
General Fill 1
(GF1)
3000
1.7
95% (Standard)
OMC ± 2%
General Fill 2
(GF2)
unlimited
unlimited
95% (Standard)
OMC ± 2%
4.
DEEMED TO COMPLY DESIGN
Batter Slopes
If Type D Material is not used in the batters, the following slopes are deemed to be a complying earthworks design.
If the Contractor proposes to use Type D Material in the batters or steeper batters, the Contractor must prepare a
design in accordance with DPTI Design Standard: Earthworks for Roads EW100.
Batter Height
Cut and Fill Batters less than 2m high:
Cut and Fill Batters 2-4 m high:
DPTI XXCxxx
Earthworks Batters
Maximum Unsupported Batter
Comment / Conditions
slope
1V:6H
Provide a forgiving road environment for
errant vehicles at low cost.
1V:4H
Do not require barriers, are able to be mown.
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CSTR: Part D25 Design – Earthworks for Roads
Edition: November 2014
Cut and Fill Batters higher than 4m:
1V:3H
Are generally not suitable for landscape
maintenance machinery access and slashing.
Batters to drains within
clear zone
1V:4H
1V:6H if slope is within 6 m of
edge of pavement
1V:3H in constrained locations
Less critical than slopes immediately adjacent
the carriageway due to reduced chance of
vehicle traverses. Drains can be traversed by
vehicles and mown for maintenance purposes
Subgrade
The Contractor is responsible for verifying that any Unsuitable Material below fill or below pavement in cuts is
removed or treated so that the earthworks design complies with the requirements of EW100. At a minimum, 600
mm of existing material must be removed under the pavement “footprint” where embankments are to be
constructed.
5.
SETTLEMENT
Settlement Limitations
Level changes in the finished pavement surface must comply with the following:
(a)
no increase in levels after completion of construction of the pavement;
(b)
maximum decrease in level of the pavement surface of 30 mm over any 12 month period following the
construction of the pavement;
(c)
maximum differential settlement of 30 mm in a longitudinal direction, measured between Settlement
Measurement Points spaced at 50 m, following construction of the pavement until the Date of Final
Completion;
(d)
maximum differential settlement of 12 mm in a longitudinal direction, measured between Settlement
Measurement Points spaced at 20 m, following construction of the pavement until the Date of Final
Completion;
(e)
maximum differential settlement of 15 mm in a transverse direction, when measured between Settlement
Measurement Points on opposite sides of each carriageway following construction of the pavement until
the Date of Final Completion;
Estimated settlement creep (extrapolated on a logarithmic time scale) at any point over this length must not exceed
50 mm over the period of 10 years following the Date of Completion.
6.
ACID SULPHATE SOILS
Potential acid sulphate soils may be present below the proposed route of the project, particularly in the northern
section. In situ soil that is excavated from below the equilibrium groundwater level, or in situ soil below the natural
equilibrium ground level that lies within the draw down zone of a groundwater dewatering system, has the potential
to become actual acid sulphate soil. Potential acid sulphate soil that is excavated or dewatered must be managed in
accordance with the acid sulphate soils component of the Environmental Management Plan for the project and Part
D020 – Design - Environmental.
7.
PERFORMANCE MONITORING
Insert requirements for settlement monitoring etc. eg:
The Contractor must implement a monitoring program that records settlement for the period between completion of
the embankment and expiry of the defects liability period. Settlement must be recorded each fortnight for the first
6 months and monthly thereafter. A total of 4 settlement recording points is required, located 5 m and 15 m from
each bridge abutment.
Settlement must be measured by a Surveyor meeting the requirements of Clause 130.1. Measurements must be
plotted graphically creep (on a logarithmic time scale) and forwarded to the Principal within 1 week. If
calculations of predicted settlement have been prepared, these must also be shown on the plot.
DPTI XXCxxx
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CSTR: Part D25 Design – Earthworks for Roads
Edition: November 2014
If a Settlement Measurement Point is disturbed or lost it must be replaced as close as practicable to the original
point before the next survey. Settlement must be determined by reference to a stable benchmark (eg a deep
benchmark).
8.
RECORDS
The following records must be provided to the Principal:
Drawings
Drawings specified in EW100.
Drawings of any temporary earthworks, including settlement limiting or accelerating methods or dewatering
temporary works.
As constructed drawings.
Reports
Design Report (refer EW100).
Implementation Records
Settlement records (where specified).
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DPTI XXCxxx
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