Section 12 – Earth Works Related to Buildings

QCS 2014
Section 12: Earth Works Related to Buildings
Part
01: General
Page 1
GENERAL ...................................................................................................... 2
1.1
INTRODUCTION ........................................................................................... 2
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.1.6
1.1.7
1.1.8
1.1.9
Scope
References
Ground Investigation
Site Clearance
Preservation of Property Not to be Affected by the Works
Disposal of Historical Artefacts
Special Requirements of Utility Authorities
Control of Ground Water
Record Procedure
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Section 12: Earth Works Related to Buildings
Part
01: General
Page 2
GENERAL
1.1
INTRODUCTION
1.1.1
Scope
1
This Section specifies the requirements for excavation and filling as necessary to facilitate
the construction of the Works. It does not include earthworks associated with trenches for
pipelines or service ducts.
2
The cost of all operations needed for the excavation and disposal work as required and
specified, including temporary and permanent support work, breaking, loading, hauling and
dumping in accordance with the provisions of the Project Documentation shall be included in
the Contractor’s rates.
3
The Contractor shall be deemed to have examined the site and verified for himself the exact
nature and quality of the materials to be excavated. The Contractor shall carry out his own
survey of the existing ground levels and satisfy that the quantities of all excavated and
imported materials are correct.
4
Removal operations shall be conducted with the least interference to the public and shall not
be started until approved by the Engineer.
5
Related Sections and Parts are as follows:
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1
Filling
Section 1
Section 2
Section 6
Section 8
Section 28
General
Building Demolition
Roadworks
Sewerage
Landscaping
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This Section
Part 3
1.1.2
References
1
The following standards are referred to in this Section:
BS 812........................Testing Aggregates
BS 1377 .....................Methods of test for soils for civil engineering purposes
BS 6906 .....................Methods of tests for geotextiles
1.1.3
Ground Investigation
1
The Contractor shall be deemed to have satisfied himself as to the character of the Site and
all the various materials, strata, ground water levels, etc., and of all items liable to affect, or
be encountered in, the excavations and earthworks.
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Section 12: Earth Works Related to Buildings
Part
01: General
Page 3
If a ground investigation is not included in the Project Documentation the Contractor shall
immediately after taking possession of the Site prepare a minimum of two trial pits in
positions to be agreed with the Engineer. Chemical analysis tests are to be carried out on
the materials from each of the pits and the results submitted to the Engineer. Similarly,
chemical analysis tests shall be carried out on any water present in the pits and the results
submitted to the Engineer. Ground investigation tests in accordance with the relevant
provisions of BS 812, BS 1377 and BS 6906 shall be undertaken where geotextiles are to be
used for temporary or permanent protection.
3
The Contractor shall inform the Engineer when the trial pits are ready for inspection and shall
not commence excavation work until approval to proceed has been given. All trial holes and
their subsequent backfilling shall be carried out at the Contractor’s expense and will only be
allowed in positions approved by the Engineer. All trial holes shall be backfilled as soon as
the required information has been obtained and open excavations shall be adequately
protected and cordoned off using temporary lights and barriers or similar method approved
by the Engineer.
4
If a ground investigation is included in the Project Documentation, it is provided solely for the
guidance of the Contractor and no guarantee is given regarding its accuracy, nor is it
guaranteed that similar conditions apply elsewhere on the Site.
1.1.4
Site Clearance
1
Before commencing any excavation or fill, the area shall be cleared of all trees, stumps,
roots, bushes, vegetation, debris, materials or other obstructions.
2
Before removal of any trees or shrubs the Contractor shall obtain written consent from the
Engineer at least two weeks in advance of the planned removal.
3
All bushes, undergrowth, etc. to be removed shall be grubbed up and disposed of in a
manner as agreed with the Engineer. Holes left by stumps or roots shall be filled with
suitable material, compacted to the Engineer’s satisfaction in accordance with Part 3 of this
Section within one week of the work being performed.
4
The Contractor shall at his own expense make good any damage done to other property
during the site clearing. Sweet soil excavated during the course of these works shall be
preserved and protected by the Contractor, until removed by the Employer or until the
expiration of the Contract.
1.1.5
Preservation of Property Not to be Affected by the Works
1
Attention is directed to the Contractor’s obligations with regards to damage, particularly with
regard to protection of property, plants and landscape and to responsibility for damage
claims.
2
The form of protection to vegetation within the Site shall be as agreed with the Engineer.
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Section 12: Earth Works Related to Buildings
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01: General
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1.1.6
Disposal of Historical Artefacts
1
Where specified, certain materials arising from site clearance and excavation work are to
remain the property of the Owner. All fossils, antiquities and other objects of interest or value
which may be found or uncovered on the Site shall remain or become the property of the
Owner. Upon discovery of such an object the Contractor shall forthwith:
(a)
use his best endeavours not to disturb or damage the object
(b)
cease work which would endanger the object or prevent or impede its removal
(c)
inform the Engineer of the discovery and precise location of the object.
The Engineer will issue an instruction on the procedure to be adopted which may include
conditions to permit the examination, excavation or removal of the object by a third party.
1.1.7
Special Requirements of Utility Authorities
1
Prior to commencing excavation work, the Contractor shall ascertain from the responsible
Utility Authorities whether any mains or services need to be diverted or cut-off in accordance
with the procedure described in Part 19 of Section 1.
1.1.8
Control of Ground Water
1
Prior to the commencement of construction at any particular location, the Contractor shall
install and maintain a system of standpipes and other devices to monitor ground water levels
in any area, which in the opinion of the Engineer, is likely to be affected by the dewatering.
The number, location and depth of all standpipes shall be to the satisfaction of the Engineer.
2
The Contractor shall check ground water levels weekly or when instructed by the Engineer.
The results of such checks shall be submitted to the Engineer in a written report within 24
hours of the level being taken. The format of the report shall be as agreed with the Engineer.
3
In the case of uncontrolled flow of water into any excavation, the Engineer reserves the right
to order the Contractor to take immediate action to control the inflow of water. Such actions
and remedial works shall be to the Engineer’s approval.
1.1.9
Record Procedure
1
If the Engineer requires foundation or formation level depths to be varied from those shown
on the drawings it shall be the responsibility of the Contractor to ensure that proper records
of the actual excavated levels are kept.
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Section 12: Earth Works Related to Buildings
Part
02: Excavation
Page 1
2
EXCAVATION ................................................................................................ 2
2.1
GENERAL ...................................................................................................... 2
2.1.1
2.1.2
Scope
References
2.2
EXCAVATION FOR STRUCTURES .............................................................. 2
2.2.1
2.2.2
2.2.3
2.2.4
2.2.5
2.2.6
2.2.7
2.2.8
Excavation Support
Removal of Water
Approvals
Inspection
Unsound Materials
Over-Excavation
Finishing to Excavation
Storage of Excavated Material
2.3
MATERIALS .................................................................................................. 4
2.3.1
2.3.2
2.3.3
2.3.4
Excavated Material
Common Excavation
Rock Excavation
Blasting
2.4
DISPOSAL OF SURPLUS MATERIAL .......................................................... 5
2.4.1
General
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Section 12: Earth Works Related to Buildings
Part
02: Excavation
Page 2
2
EXCAVATION
2.1
GENERAL
2.1.1
Scope
1
This Section specifies the requirements for the excavation for structures, culverts, headwalls,
catch basins, manholes, inlets, retaining walls and the like. The work includes all necessary
clearing and grubbing and the disposal of all material resulting from such excavation. The
work also includes the provision, and subsequent removal, of all necessary bailing, drainage,
pumping, sheeting, strutting, coffer dam construction and crib construction.
2
Rates for excavation shall include for excavation in any material. Excavation in any material
shall include common excavation, side shoring, support systems, excavation in artificial hard
material and shall be inclusive of all encountered impediments, including roots, boulders etc.
Blasting will not be permitted without the written approval of the Engineer.
3
Related Sections and Parts are as follows:
Section 1
Section 6
General
Roadworks
References
1
The following standards are referred to in this Part;
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2.1.2
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BS 1377 .....................Method of test for soils for civil engineering purposes
2.2
EXCAVATION FOR STRUCTURES
2.2.1
Excavation Support
1
Prior to Commencing any structural excavation work which is 1.5 m or greater in depth, the
Contractor shall design an excavation support system.
2
Details of the excavation support system shall be submitted to the Engineer for review and
approval at least one week before any excavation work commences. Details of the
excavation support system shall be complete with, but not limited to, the following:
(a)
drawings of the structural support members showing materials, sizes and spacing,
(b)
calculations showing the maximum theoretical deflection of the support member.
3
The system is to be designed so that no members extend through surfaces exposed in the
finished construction, and no shoring or bracing is placed under permanent structures.
4
The Contractor shall submit to the engineer calculations of lateral earth pressure for the full
excavation depths, surcharge loads of any description, equipment loads, forces at various
stages of support during excavation, the maximum design loads to be carried by various
members of the support system and strut pre-load forces.
5
If the structure support system proposed includes tieback anchors, the Contractor’s
submitted details shall include drawings that show the profile of the soil in which each anchor
is to be installed.
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Section 12: Earth Works Related to Buildings
Part
02: Excavation
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Tieback anchors that project beyond the vertical limits of the Site boundary on to adjoining
property shall only be permitted if permission to do so is given by the owner of the property
in writing. Copies of such written permission shall be submitted to the along with excavation
support system proposals.
2.2.2
Removal of Water
1
At locations where the excavation extends below the groundwater table, a dewatering
system is to be provided which will lower ambient groundwater levels. The resulting
groundwater level shall be at a depth which is sufficiently below the excavation level so as to
allow the safe and proper execution of the work. The resulting foundation level shall be a
stable, dry sub-grade which is suitable for the execution of subsequent operations.
2
The Contractor is to design the dewatering methods and settling basins so that no critical
amounts of soil, sand or silt are removed during either the dewatering operations.
3
Complete working drawings showing the type of dewatering and groundwater control system
proposed shall be submitted to the Engineer for his review. The Contractor’s submittal shall
include drawings that show the arrangement, location and depths of the proposed
dewatering system. A complete description of the equipment and materials to be used and
the procedures to be followed to be given, together with details of required standby
equipment and standby power supply. The Contractor shall also indicate his proposed
location(s) for the discharge of extracted groundwater.
4
The dewatering system design should also include the details of measures required to
prevent damage due to settlement of roads, pavements, utilities, sewers, buildings and other
structures outside the excavation but within the area affected by the dewatering.
2.2.3
Approvals
1
The designs of the structure excavation support system and the dewatering systems
specified above is to be prepared by and signed by a qualified engineer experienced in this
type of design work. Approval of the designs and shop drawings will not relieve the
Contractor of the adequacy and performance of these temporary works.
2.2.4
Inspection
1
In addition to the provisions of Part 13 of Section 1, the Contractor shall also undertake the
following described in the following Clauses unless otherwise instructed by the Engineer.
2
Following a detailed inspection of all adjacent structures, the Contractor shall prepare a
report on the pre-construction condition of all structures that may be affected during
construction of the Works. The report will include photographs, drawings and sketches with
levels and dimensions fully illustrating the structure's condition. In particular, it shall note any
existing damage or structural inadequacy. Deficiencies and damage are to be suitably
marked on the structure in a way that it is not permanently defaced.
3
Three (3) copies of the Report shall be submitted for the approval of the Engineer. Once
approved, five (5) additional copies shall be supplied to the Engineer.
4
The Contractor shall carry out a survey of levels of undisturbed ground before commencing
any excavations.
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Section 12: Earth Works Related to Buildings
Part
02: Excavation
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When the excavation has been carried down to formation level the Contractor shall advise
the Engineer’s Representative that the excavation is ready for inspection and the Engineer’s
Representative shall, without reasonable delay, inspect the excavation unless he considers it
unnecessary.
2.2.5
Unsound Materials
1
Any loose, improperly compacted, soft or other unsuitable material which is encountered
below or adjacent to structural foundation levels shall be completely removed, backfilled with
a suitable material and compacted to 95% of the maximum dry density as determined by BS
1377 Part 4. Backfilling shall be done in layers with an unconsolidated thickness not
exceeding 200 mm up to the foundation level. The limits of such work shall be as directed by
the Engineer. Alternatively, the Engineer may instruct that removed material be replaced with
Class C25 concrete.
2.2.6
Over-Excavation
1
Any over excavation is to be backfilled with Class C25 concrete at the Contractors expense.
2.2.7
Finishing to Excavation
1
All rock or other hard foundation material is to be cleaned of all loose material. All seams or
crevices are to be cleaned and grouted. All loose and disintegrated rock and thin strata is to
be removed.
2
When the structure is to rest on material other than rock, excavation to final grade should not
be made until just before the structure is to be placed/constructed and special care is to be
taken not to disturb the excavated surface. The surface required shall be rolled and
compacted to 95% of the maximum dry density.
2.2.8
Storage of Excavated Material
1
Excavated material is not to be stored or deposited in such a way as to endanger structures
or cause an obstruction of any kind.
2.3
MATERIALS
2.3.1
Excavated Material
1
All excavated material will be the property of the Owner and no material shall be removed,
transported and disposed of without the prior written approval of the Engineer.
2.3.2
Common Excavation
1
Common excavation consists of the excavation and satisfactory disposal of all soils, certain
strata and rock boulders less than one (1) cubic metre in volume. Strata which are altered
and weathered and are in place, but which are not firm enough, or in the opinion of the
Engineer are not rigid enough to have all the characteristics of rock excavation is to be
classified as common excavation.
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2.3.3
Rock Excavation
1
Rock excavation consists of the excavation and satisfactory disposal of all unaltered and
unweathered firm and rigid igneous, metamorphic and sedimentary solid rock that in the
opinion of the Engineer can only be excavated by the use of pneumatic hammers or other
such similar apparatus.
2.3.4
Blasting
1
Blasting will not be permitted without prior approval. (Refer to Section 6: Roadworks).
2.4
DISPOSAL OF SURPLUS MATERIAL
2.4.1
General
1
All materials arising from site clearance or excavation which are surplus, suitable or
unsuitable for use in the Works will become the property of the Owner and will not be
disposed of by the Contractor either off the Site to an approved tip without written approval
from the Engineer. If directed, or otherwise agreed by the Engineer, the Contractor may
dispose of surplus material on the Site in an approved manner as directed by the Engineer.
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Section 12: Earth Works Related to Buildings
Part
03: Filling
Page 1
3
FILLING ......................................................................................................... 2
3.1
GENERAL ...................................................................................................... 2
3.1.1
3.1.2
Scope
References
3.2
EARTHWORKS MATERIALS ........................................................................ 2
3.2.1
3.2.2
3.2.3
3.2.4
Top Soil
Suitable Material
Unsuitable Material
Utilisation of Excavation Materials
3.3
MAIN PLANT FOR EARTHWORKS CONSTRUCTION ................................ 3
3.3.1
General
3.4
BACKFILLING ............................................................................................... 3
3.4.1
General
3.5
COMPACTING IMPORTED OR SELECTED EXCAVATED FILL
MATERIAL ..................................................................................................... 4
3.5.1
3.5.2
General
Water
3.6
FILL BELOW GROUND SLABS .................................................................... 5
3.6.1
General
3.7
FILLING ......................................................................................................... 5
3.7.1
Concrete Blinding
2
2
2
2
3
3
3
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Section 12: Earth Works Related to Buildings
Part
03: Filling
3
FILLING
3.1
GENERAL
3.1.1
Scope
1
This Part specifies materials for filling purposes.
2
Related parts and Section are as follows:
Page 2
This Section
Part 2
Section 6
Excavation
Roadworks
3.1.2
References
1
The following Standards are referred to in this Part:
BS 812........................Testing Aggregates
BS 1377......................Methods of test for soil for civil engineering purposes
EARTHWORKS MATERIALS
3.2.1
Top Soil
1
Top soil is to be fertile, friable soil obtained from well drained arable land and to be free
draining, non-toxic and capable of sustaining healthy plant growth.
3.2.2
Suitable Material
1
Suitable material for earthworks shall be approved soil with a liquid limit not exceeding 35%
and a plasticity index not exceeding 10%. The material passing the 0.075 mm sieve shall not
exceed 20% and the organic matter content shall not exceed 2% (as determined by BS 1377
– Part 3).
2
Where excavated rock is to be used as fill material elsewhere on the site, the Contractor is
responsible for ensuring that the excavated rock meets the requirement of the Specification
for fill material.
3
The Contractor is responsible for mixing the excavated rock with suitable fill material
imported and/or excavated from within the site should it be necessary in order to produce a
suitable fill material that complies with the requirements of the Specification and he should
allow in his rates and programme for carrying out the work.
4
Sweet soil and any excavated materials which are considered re-usable by the Engineer,
shall be preserved and protected by the Contractor, until they are removed by the Owner or
until the expiration of the Contract.
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3.2
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No excavated suitable material is to be removed from the Site without the Engineer’s written
permission. Should the Contractor be permitted to remove suitable material from the site to
suit his operational requirements, then he is to make good any consequent deficit or filling
arising therefrom at his own expense.
3.2.3
Unsuitable Material
1
Unsuitable materials include:
rock particle exceeding 75mm in size
(b)
organic material (as defined in BS 1377 Part 3) containing greater than 2% stumps
and other perishable material
(c)
material susceptible to spontaneous combustion
(d)
soils of a liquid limit exceeding 35% and/or a plasticity index exceeding 10%.
(e)
material containing more than 5% of water soluble salts by weight of dry soil
(individually, water soluble chloride exceeding 1% or water soluble sulphate exceeding
1.5%) or more than 10% of acid-soluble salts (individually, acid soluble chloride
exceeding 2% or acid soluble sulphate exceeding 3.0%) as determined by BS 1377:
part 3
(f)
any other material which the Engineer may deem to be unsuitable for earthworks
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(a)
Utilisation of Excavation Materials
1
All excavated material determined as suitable by the Engineer, is to be utilised as backfill.
The surplus material shall be disposed of as specified in Part 2 of this Section.
3.3
MAIN PLANT FOR EARTHWORKS CONSTRUCTION
3.3.1
General
1
The Contractor is to employ only plant which is suited to the soils to be handled. He should
not at any time use plant which damages or reduces the natural strength of the soil either in
its in-situ state or during handling and placing or in its final compacted state. Unsuitable or
faulty plant shall be removed from the work site and borrow pits at the order of the Engineer.
3.4
BACKFILLING
3.4.1
General
1
Excavation is only be backfilled after the permanent works therein have been approved and
after the removal of any building debris or deleterious material from the excavations.
2
Selected excavated material will normally be used or backfilling in the manner described in
Clause 3.5 of this Part. Where the excavated material is not considered suitable, selected
material form an approved source is to be used.
3
The backfill will be brought to a suitable level above grade to provide for anticipated
settlement and unless indicated otherwise, is to be sloped away from the structure.
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Section 12: Earth Works Related to Buildings
Part
03: Filling
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The bottom of all excavations are to be probed and any poor bearing area shall be reported
to the Engineer who will direct remedial work. Soft spots and other unsound materials are to
dealt with as specified in Part 2 of this Section.
5
In circumstances where backfill has to be deposited below standing water, only rock, as
specified in Section 6, Roadworks, is to be used.
3.5
COMPACTING IMPORTED OR SELECTED EXCAVATED FILL MATERIAL
3.5.1
General
1
Fill to be compacted by a suitable plate type vibrator, pedestrian operated vibrator roller,
small tandem roller or other approved compaction plant.
2
The material is to be placed in layers within the effective range of compaction of the plant
provided that the maximum loose (uncompacted) thickness of each layer dose not exceed
200 mm.
3
The material is to be watered and mixed as necessary to ensure that prior to compaction the
moisture content of the whole layer is ± 3% of the optimum moisture content. Compaction of
each layer is to continue until a density of a least 95% of the maximum dry density has been
achieved.
4
The dry density/moisture content relationship will be determined by the heavy compaction
test (4.5% rammer method) of BS 1377.
5
All fill material used in earthworks shall be compacted as per related Specification by plant
approved by the Engineer for that purpose. If required by the Engineer the Contractor shall
carry out compaction trials on the material supplemented by laboratory testing to determine
the correct plant and number of passes required to achieve the specified requirements.
6
Potable water shall be used for compaction of all fill material within the area of excavation.
7
The Contractor shall carry out moisture content determinations at frequent intervals or when
there is a change in the material on the soils undergoing compaction so as to ensure that the
moisture content of the soil is within the optimum range for the field compaction determined
from compaction trials.
8
All adjustment of moisture content shall be carried out in such a way that the specified
moisture content remains uniform through out compaction.
9
No completed fill layer shall be covered by the next layer until it has been tested, inspected
and approved by the Engineer.
10
The finished surface of earthworks for paved surfaces (other than public roads) shall be
shaped and rolled and then tested for accuracy so that maximum local irregularities in the
finished profiles lie within the tolerance of  20mm for formation, as well as  10mm and 
5mm respectively for longitudinal and transverse profiles of finished surfaces, when tested by
a straight edge or level instrument. The frequency of local irregularities shall be at the
discretion of the Engineer.
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03: Filling
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Where fill material is to be deposited in areas where the existing ground is sloping, the
Contractor shall excavate benches so that fill material is deposited onto a horizontal surface.
The levels of the benching terraces shall match the layers of the fill material that are
deposited in the adjacent areas.
3.5.2
Water
1
The water to be mixed with the soil / fill materials to achieve the desired moisture content in
the filling / earthworks operations shall be potable.
3.6
FILL BELOW GROUND SLABS
3.6.1
General
1
The installation of cable ducts for service entries and service pipework is to be completed
before placing of the fill to receive the ground slab.
2
The compacted fill or hardcore is to be shaped and trimmed to the required levels and
dimensions and blinded with sand.
3.7
FILLING
3.7.1
Concrete Blinding
1
Immediately on completion of excavations for concrete structures a blinding layer of concrete
Grade OPC 25 not less than 75mm thick shall be placed to prevent deterioration of the
formation and to provide a clean working surface for the structure.
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Section 12: Earth Works Related to Buildings
Part
04: Utility Trenches
Page 1
4
UTILITY TRENCHES ..................................................................................... 2
4.1
GENERAL ...................................................................................................... 2
4.1.1
4.1.2
4.1.3
4.1.4
Scope
References
Excavation of Utility Trenches
Backfilling of Utility Trenches
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04: Utility Trenches
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4
UTILITY TRENCHES
4.1
GENERAL
4.1.1
Scope
1
This Part specifies the requirement for utility trenches. It does not include trenchworks for
pipelines and service ducts.
2
Related Sections and Parts are as follows:
This Section
Part 2
Filling
Part 3
Excavation
4.1.2
References
1
The following standards are referred to in this Part:
BS 1377
Methods of tests for soils for civil engineering purposes.
Excavation of Utility Trenches
1
The trench to be excavated with the width and to the depth shown on the drawings or as
indicated by the Engineer.
2
The sides of pits and trenches are to be vertical and adequately supported at all times.
Excavation may if considered necessary be battered with a safe slope, but only with the
Engineer’s written permission.
3
Care is to be taken to excavate to the depths indicated. Where rock is encountered, the rock
is to be excavated 150 mm lower than the required depth. Such depth in rock is to be
backfilled with approved fill material and compacted as specified and/or as directed by the
Engineer.
4
Excavated material will, if found unsuitable as defined in Part 3 of this Section, be disposed
of to an approved tip and replaced with suitable material. All surplus material to be disposed
of in accordance with Part 2 of this Section.
4.1.4
Backfilling of Utility Trenches
1
After the utilities have been laid, the trench refilling is to commence with approved fill in
compacted layers not exceeding 150 mm unconsolidated thickness. Each layer shall be well
compacted by hand with iron rammers weighing not less than 5 kg, until the trench has been
filled to a height of 300 mm above the top of the utility.
2
The remainder of the trench is then to be refilled in compacted layers not exceeding 250 mm
unconsolidated thickness. Each layer being well compacted, with power rammers, vibrating
plate compactors or other mechanical means of a type to be approved until the ground is
thoroughly consolidated up to the required level for surface reinstatement. Each layer is to be
compacted to 95% of its maximum dry density as determined by BS 1377.
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Section 12: Earth Works Related to Buildings
Part
04: Utility Trenches
Page 3
3
Trenches are not to be backfilled until all required tests are performed on the utilities and until
the Engineer has verified that the utilities have been installed in accordance with the Project
Documentation.
4
Where cover to utilities is less than 400 mm, or where ordered by the Engineer, protection in
the form of precast concrete tiles is to be provided according to an approved drawing or as
ordered by the Engineer.
5
PVC warning tape shall be laid above the utility or the concrete tiles, after partial backfilling
and approximately 300 mm below finished ground level.
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Section 12: Earth Works Related to Buildings
Part
05: Installation of Protective Membranes
Page 1
5
INSTALLATION OF PROTECTIVE MEMBRANES ....................................... 2
5.1
GENERAL ...................................................................................................... 2
5.1.1
5.1.2
5.1.3
Scope
References
General Requirements
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QCS 2014
Section 12: Earth Works Related to Buildings
Part
05: Installation of Protective Membranes
Page 2
5
INSTALLATION OF PROTECTIVE MEMBRANES
5.1
GENERAL
5.1.1
Scope
1
This Part specifies geotextile fabric systems used for temporary or long term stabilisation of
earthworks during construction.
2
Related Sections and Parts are as follows:
Section 5
Concrete
Section 6
Roadworks
5.1.2
References
1
The following standards are referred to in this part:
BS 6906......................Methods of test for Geotextiles
General Requirements
1
In areas where the Engineer deems the use of geotextile fabric necessary, the Contractor is
to furnish and place geotextile fabric as specified and as directed by the Engineer.
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5.1.3
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The geotextile fabric furnished by the Contractor is to be of an approved grade suitable for
placement over fine sand. The geotextile fabric shall be a woven or non-woven fabric
consisting only of long chain polymeric filaments or yarns formed into a stable network such
that the filaments or yarns retain their relative position to each other. The fabric is to be
stabilised against ultra violet light, inert to commonly uncounted chemicals and chemical
properties of the in-situ soil and water, and it should conform to the following minimum
requirements:
Weight
135 g/m
2
2
2
Thickness under load (2 kN/m )
0.7 mm
Tensile Strength (200 mm width) ASTM D1682
1.6 kN
Puncture Resilience (DIN 54307)
1.5 kN
Permeability
50 litres/m /s
2
The surface to receive the geotextile fabric is to be prepared to a relatively smooth condition
free of obtrusions, depressions, and debris. The geotextile fabric should not be laid in a
stretched condition. In the event that the width of the proposed area for fabric requires more
than one panel width of fabric, the panels are to be overlapped a minimum 15 percent of the
panel width. Longitudinal joints in the fabric are to have an overlap of 500 mm. To prevent
slippage of the overlapping fabric, the areas of overlap are to be stabilised as approved by
the Engineer with pins, anchor blocks, or aggregate piles. In the event that construction
machinery is used to place the fabric, the working platform for the machinery should be the
soil and not the previously laid fabric.
QCS 2014
Section 12: Earth Works Related to Buildings
Part
05: Installation of Protective Membranes
Page 3
3
Prior to placement of the granular material (stabilising crushed material) the Contractor is to
spread a layer of sand over the geotextile fabric as directed by the Engineer. The aggregate
material should not be dumped directly on the fabric. Haulage trucks are not to be driven on
the fabric. The aggregate is to be spread by a wheeled front-end loader. The blade or bucket
is to be kept sufficiently high so that the aggregate is not being pulled over the fabric, but
being dropped at a minimum height to the satisfaction of the Engineer.
4
Fabric damaged or displaced before or during installation or during placement of overlaying
aggregate material is to be replaced of repaired to the satisfaction of the Engineer at the
Contractor’s expense.
5
Where pipes or other elements pass through the geotextile fabric, the openings around such
are to be made watertight by methods as approved by the Engineer.
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END OF PART