NATIONAL
STANDARD
TCVN
9436 : 2012
HIGHWAY
EMBANKMENTS AND CUTTINGS – CONSTRUCTION AND QUALITY CONTROL
Foreword
The TCVN 9436:2012 is compiled by
Institute of Transport Science and Technology, proposed by the Ministry of
Transport, inspected by the Commission for the Standards, Metrology and Quality
of Vietnam, and issued by the Ministry of Science and Technology.
The TCVN 9436:2012 is converted from
"Technical procedures for construction and commissioning of railway and
road embankments and cuttings promulgated by the Minister of Transport on July
22, 1975 under Decision No. 1660 QDKT (hereinafter referred to as “1975
Procedure”).
HIGHWAY EMBANKMENTS AND
CUTTINGS – CONSTRUCTION AND QUALITY CONTROL
1. Scope
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1.2. This Standard can be used as reference in
construction and quality control of embankments and cuttings of special roads,
specialized roads, or rural roads.
2. Referencing document
The following documents are necessary for
application of this document. If a reference document is mentioned together
with its publishing year, only the referenced edition shall prevail. If a
reference document is not mentioned together with its publishing year, the
latest version and all its amendments and revisions (if any) shall prevail:
TCVN 5729:2012 Freeway and Expressway -
Design requirements.
TCVN 4054:2005 Freeway and Expressway -
Design requirements.
TCVN 2737, Load and impact. Design
standards.
TCVN 8864:2011 Standard Test Method for
Measuring Road Pavement Surface Roughness Using a 3.0 m Straight Edge.
22 TCN 332-06*) Procedures for determining
CBR of soil and gravel in laboratory.
22 TCN 346-06*) Procedures for determining
compactness of road embankments, cuttings, and foundation via sand cone test.
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22 TCN 221*) Traffic structures in
earthquake zones. Design standards.
22 TCN 242*) Environmental impact assessment
in project development.
22 TCN 263*) Highway surveying procedures.
22 TCN 211*) Flexible pavement. Design
requirements and indicators.
22 TCN 262*) Procedures for survey and
design of road bed filling on weak ground.
22 TCN 171*) Procedures for structural
geological survey and design of road base stability solutions in areas prone to
erosion, landslide.
ASTM D 4914 – 99 Standard test method for
density of soil and rock in place by the sand replacement. Method in a Test
Pit.
ASTM D 5030 – 04 Standard test method for
density of soil and rock by the water replacement. Method in a Test Pit.
*): Profession standards (TCN) will be
converted to TCVN
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AASHTO M145-91(2004) The classification of
soils and soil-aggregate Mixtures for highway construction purpose.
3. Terms and
definitions
In this Standard, the following definitions are
used:
3.1. Highway embankments and cuttings.
Highway embankments and cuttings constitute
subgrade and are basic elements of highway. Embankments and cuttings include
the entirety of filled and removed sections (where earth or rocks are removed; earth,
rock, or other materials deposited) within design (construction) cross section
of highway with the exception of sections associated to pavement.
Design cross section of embankments and
cuttings is limited by subgrade slopes, surface of road shoulder, boundary of
pavement, and related areas that require additional treatments to improve
strengths and stability of the pavement (earth replacement, drainage,
installation of structures for supporting and protecting embankments and
cuttings, weak earth treatment, corrosion prevention, etc.)
3.2. Normal highway embankments and cuttings.
Refers to a type of embankments and cuttings constructed
by regular earthwork machinery and treated by regular solutions within the
design cross section, including regular drainage and slope protection solutions.
3.3. Special highway embankments and cuttings.
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3.4. Embankment.
Refers a type of subgrade formed by filling earth,
rocks (or other materials) to achieve an elevation higher than natural
elevation. Embankments are limited by fill slopes, fill shoulder, boundary of
pavement structure, and the range to which earth replacement takes place below
the natural terrain (if any).
Embankment under this document consists of 3
types:
3.4.1. Earth fill embankment.
Earth that contains less than 30% of its weight
in rocks, pebbles of 19 mm in dimensions to a maximum of 50 mm. This type of
materials can have its standard compactness determined in laboratories in
accordance with 22 TCN 333-06.
3.4.2. Earth - Rock embankment.
Earth that contains 30% to 70% of its weight in
rocks of 50 mm in dimensions to the maximum dimension under 5.4.
3.4.3. Rock - Fill embankment.
Earth that contains 70% of its weight or more
in rocks of 37,5 mm or higher in dimensions. Construction of rock-fill
embankment is not regulated by this document.
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Refer to a type of road formed by removing
earth and rock below the natural elevation.
3.6. Embankments and cuttings.
Refer to a type of subgrade that consists of
both embankments and cuttings on the same cross section.
3.7. Slope.
Lateral boundary of cuttings or embankments or
embankments and cuttings.
3.8. Subgrade and the upper layer of Subgrade
Refers to section of embankments and cuttings
that is 80 to 100 cm deep from the bottom of the pavement structure. This part
of embankments and cuttings requires high load-bearing capability to work with
pavement in withstanding wheel load. Depth value shall increase for roads
accommodating high number of heavy vehicles.
Sections within subgrade depth are usually
divided into 2 sub-sections:
The top 30 cm sub-section and the bottom of the
pavement (the topmost layer); The remaining sub-section of the subgrade below
(50 to 70 cm).
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4. General requirements
4.1. Embankments and cuttings shall be so built to
satisfy geometry requirements according to design. Tolerance is provided under
Schedule 1.
Schedule: Permissible
tolerance (relative to design) of geometry elements of constructed embankments
and cuttings
Element
Type and class of
road
Inspection method
Class I, II, III
expressway
Class IV, V, VI road
1. Width of pavement surface
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Not lower than design
value
Record a measurement at every 50 m in length.
2. Lateral gradient and super-elevation
gradient (%)
± 0,3
± 0,5
Record a measurement via the use of optical
level at every 50 m in length.
3. Slope gradient (%)
Not higher than
design by
+10 (*)
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+15 (*)
Record a measurement via the use of
appropriate measuring instruments at every 20 m in length.
4. Centerline of the road (mm)
50
100
Record a measurement at every 50 m in length
and at TD (***), TC (****) of curved sections.
5. Elevation on cross section (mm)
+10; -15
(+10; -20) (**)
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(+10; -30) (**)
Record a measurement at every 50 m in length
along the centerline of the road.
6. Roughness of slope measured by the largest
gap of 3 m straight edge
- Slope of embankment (mm)
- Slope of cutting (mm)
30
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50
50
80
- Not applicable to rock slope.
- Place a 3 m straight edge on a slope cross
section and sweep the straight edge to find the largest gap
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7. Ditches not built of rocks or not
reinforced:
- Elevation of the bottom (mm)
+0, -20
+0, -30
Record measurements of two points at every 50
m in length via the use of optical level
- Dimensions of cross section
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Not lower than design
value
Not lower than design
value
Record a measurement
of cross section at every 50 m
- Gradient of ditch slope
Not higher than
design value
Not higher than
design value
Record a measurement at every 50 m.
- Evenness of ditch edges (mm)
+ 50
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Record a measurement
at every 50 m along the edge using a 20 m measuring tape.
8. Constructed ditches
- Compression strength of plaster
Compliant with design
requirements
Compliant with design
requirements
For every mixing
ratio in a construction shift, separate into 2 test samples
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50
100
Record a measurement
at every 50 m via the use of theodolite.
- Dimensions of cross section (mm)
± 30
± 50
Record a measurement
at every 50 m.
- Thickness of constructed layer
Not lower than design
value
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Record a measurement
at every 50 m
- Dimension of foundation buffer layer
Not lower than design
value
Not lower than design
value
Record a measurement
at every 50 m.
- Elevation of the bottom (mm)
± 10
± 15
Record a measurement
at every 50 m.
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+ 50
+ 70
Similar to non-built
ditches.
(*) Applicable to rock embankments and
cuttings up to 30 m in consecutive length;
(**) Applicable to rock embankments and
cuttings.
(***) TD: first marker in curved section.
(****) TC: last marker in curved section.
4.2. The surface of each layer of earth deposited on
embankments and cuttings and the topmost layer of the road after construction
has completed (regardless of embankments or cuttings) must achieve the required
roughness below:
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- In respect of highways of other class, 70% of
gaps measured by a 3 m straight edge must not exceed 15 mm, remaining gaps
measured by a 3 m straight edge must not exceed 20 mm.
NOTE:
- 5% of gaps can exceed the highest gap value
which does not exceed 1,4 the values corresponding to the required roughness;
- Roughness measurement methods and density
shall conform to TCVN 8864:2011.
4.3. Type of earth and load-bearing capability of
materials of embankments and cuttings shall satisfy requirements under Article
5. Embankments and cuttings shall meet compactness required under Schedule 2.
Schedule 2: Required
compactness of embankments and cuttings (standard compaction method under 22
TCN 333-06).
Type and parts of
embankments and cuttings
Depth from the bottom
of the pavement (cm)
Compactness K of
embankments and cuttings
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Class I through class
IV road
Class V through class
VI road
Embankments
Where pavement thickness is greater than 60
cm
30
≥ 1,0
≥ 0,98
≥ 0,95
Where pavement thickness is less than 60 cm
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≥ 1,0
≥ 0,98
≥ 0,95
Beneath the
aforementioned depth
The entirety of embankments (in case of fresh
embankments).
≥ 0,98
≥ 0,95
≥ 0,93
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Up to 80
≥ 0,93
≥ 0,90
Up to 100
≥ 0,95
Cuttings and non-embankments, non-cuttings
(natural subgrade (**))
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≥ 1,0
≥ 0,98
≥ 0,95
30 to 80
≥ 0,93
≥ 0,90
30 to 100
≥ 0,95
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(*) This situation applies where low
embankments of subgrade partially incorporate natural soil;
(**) Where natural base does not meet the
required compactness under Schedule 2, rough up the sections where
compactness is not met then compact until requirement is met.
4.4. Compactness requirements for earth-rock
embankments under 7.3.11.
4.5. Drainage system within subgrade vicinity shall
be so constructed to comply with design requirements (in terms of location,
dimensions, materials), construction quality must satisfy requirements under
this document (Schedule 1).
4.6. Solutions must be taken during construction of
embankments and cuttings in order to ensure absolute safety for people,
construction machinery, local inhabitants, and property.
4.7. Necessary actions must be taken during
construction of embankments and cuttings in order to prevent negative impact on
ecosystem, environment, limit dust pollution, noise, and protect existing
vegetation; especially solutions for reasonably handling wastes produced by
construction of embankments and cuttings (including waste soil), do not dump
waste soil and materials or gather fill materials without permission or in a
manner that negatively affects the environment and natural scenery.
4.8. During construction process, regulations of the
law pertaining to protection of cultural heritage and historical relics must be
adhered to. Where relics or heritages are found during construction, the scene
must be preserved and the situation must be reported to competent authorities.
5. Materials of
embankments and cuttings
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- Humus, peat (group A-8 according to AASHTO
M145);
- Humus mixed with organic where organic
components exceed 10,0%, earth mixed with grass, roots, and domestic waste
(AASHTO T267-86);
- Earth mixed with more than 5% soluble salts
(see Appendix D for test method);
- Clay with high expansion above 3% (tests for
determination of expansion compliant with 22 TCN 332-06);
- Group A-7-6 clay (compliant with AASHTO M145)
with group index of 20 or higher;
In absence of other types of earth, solutions
must be taken to improve the aforementioned earth types before using them as
materials for embankments and cuttings such as: eliminating disadvantageous
elements, processing poor soil by adding lime, adding sand, or taking actions
to improve compactness, limiting water permeation, etc. The aforementioned
solutions must be assessed via tests in laboratories, at the scene, and
approved in accordance with project management regulations.
5.2. Granular earth of A-4 and A-5 groups (according
to classification under AASHTO M145) must not be used as materials for parts of
embankments and cuttings that are below inundation level or groundwater table
and must not be used in subgrade of embankments and cuttings.
5.3. Embankment materials must have minimum CBR
(California Bearing Ratio) compliant with Schedule 3.
Schedule 3: Minimum CBR
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Minimum CBR%
Embankments and
cuttings of expressways, class I, class II road
Embankments and
cuttings of class III, class IV road employing high grade A1 surface
Embankments and
cuttings of other roads and not employing high grade A1 surface
Embankments
- Topmost 30 cm
- Section between 30 cm and 80 cm
- Section between 80 cm and 150 cm
- Section from 150 cm
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- Topmost 30 cm
- Section between 30 cm and 100 cm for
expressways, class I, class II, class III roads, and between 30 cm and 80 cm
for other road classes
8
5
4
3
8
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6
4
3
2
6
4
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3
3
2
5
3
NOTE:
CBR is determined in accordance with 22 TCN
332-06 corresponding to compactness requirements under Schedule 2.
5.4. The maximum granular dimensions of pebbles,
gravels, rocks in earth in case of earth-rock embankments is 100 mm in respect
of embankments in subgrade and 150 mm in respect of embankments below subgrade.
Where moderately hard and hard rocks are used as materials for embankments
below subgrade (compression strength above 20 MPa), the maximum granular
dimensions may equal 2/3 the compacted thickness of earth and rock layers
during construction. In respect of soft rocks or highly-weathered rocks
(compression strength at 20 MPa or lower), the maximum granular dimensions may
equal compaction thickness as long as CBR satisfies requirements under Schedule
3.
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5.5.1. Where embankments and cuttings consist of sand,
slopes and peaks of the embankments and cuttings must be covered by blankets in
accordance with requirements under 7.4.4 of TCVN 4054. In this case, blanketing
materials on the slopes must also be compliant with requirements under 5.1,
5.2, 5.3, and 5.4.
5.5.2. If blanketing materials are incorporated and
used as foundation capping layer, the blanketing materials must also be
compliant with requirements under 2.5.2 of 22 TCN 211-06.
5.5.3. Where appropriate blanketing materials are not
available, other alternatives satisfying the aforementioned requirements must
be proposed. Alternative solutions must be applied for approval in accordance
with project management laws.
6. Embankments and
cuttings construction preparation
6.1. Prior to construction of embankments and
cuttings, conduct site survey, research into design dossiers, prepare detail
construction design which prescribes detail earth distribution solutions (where
is removed earth transported to or dumped at; where does deposited earth come
from), determine type of construction machinery and equipment appropriate to
each type and each section of embankments and cuttings, and prescribe solutions
of ensuring quality, protecting the environment and occupational safety.
6.2. Prior to construction of embankments and
cuttings, temporary roads capable of accommodating vehicles and machinery in
all weather conditions must be provided. Temporary roads and vehicle, machinery
operation thereon must not negatively affect operation of existing roads, cause
congestion, loss of safety, or negatively impact other structures, cultivation
and daily activities of local inhabitants of adjacent areas. For the purpose of
construction, improvement, and renovation of existing roads, contractors have
the responsibility to maintain the roads, adopt solutions for maintaining
traffic safety and ensuring regular operation of all other vehicles.
6.3. Prior to construction of embankments and
cuttings, earth and rock experiment basis must be available for the purpose of
controlling construction quality.
6.4. Adequate quantities of vehicles, construction
machinery, and equipment according to requirements and schedule under approved
construction design must be prepared. Adequate quantities of workshops and
forces must be provided for the purpose of preserving, maintaining, repairing
construction vehicles and machinery. Advanced, modern construction vehicles and
machinery are recommended.
6.5. Preparation of construction sites.
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This task must satisfy requirements applicable
to route restoration work under 15.2 through 15.8 corresponding to surveying
stage for preparation of construction drawings under Procedures for highway
surveying 22 TCN 263 - 2000 in both markers to be restored and measurement
accuracy in marker restoration.
6.5.2. In addition to route restoration which serves
further construction work, implement additional geodesic grids with premise and
elevation limitations (drawing grids) specifically by adding markers
(coordinates, elevation) along relevant routes. These markers are usually
positioned every 0,5 km along the route and at major bridges, medium-sized
bridges, tunnels, grade-separated intersections, areas with high embankments or
deep cuttings, and areas with embankment and cutting supporting structures,
etc.
Measurement accuracy and technical indicators
of the drawing grids must match those under requirements for measurement and
drawing at 1/500 scale under Appendices 6.4 and 6.5 of Procedures for highway
surveying 22 TCN 263 - 2000 in construction of embankments and cuttings of
expressways, class I roads, class II roads and requirements for measurement and
drawing at 1/1000 scale for class III roads or lower.
6.5.3. For the purpose of route restoration, clearly
determine scope of site preparation that serves construction of embankments and
cuttings and road structures.
6.5.4. Clearing of embankment and cutting construction
premise.
Prior to construction of embankments and
cuttings, vegetation must be cleared, organic soil must be removed, and
obstacles within construction sites must be removed in a manner that satisfies
specific requirements below:
- All large boulders at cuttings and
embankments below 1,5 m that obstructs construction vehicles and machinery must
be removed. Where volume of the boulder is greater than 1,5 m3, blasting shall
be employed to break the boulders into smaller size to allow vehicles and
machinery to remove them from construction site.
- Trees and branches, including those encroaching
construction site must be cleared and felled; tree stumps in embankment
sections below 1,5 m in height must be cleanly removed; in other cases, tree
stumps taller than natural elevation by less than 10 cm can be left as is (in
which case tree stumps must be covered in earth then compacted as a part of
embankments and cuttings).
- Other structures or obstacles (including
tombs, wells, stagnating ponds, etc.) in construction site must be relocated or
disposed in accordance with requirements and guidelines of design documents;
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- Dumping or disposal of wastes must comply
with regulations of the law and local regulations and must be done in a way
that does not affect adjacent residential areas and structures. Where waste
dumping sites are located outside of boundary markers of site preparation,
permission granted by local government shall be required.
6.5.5. Drainage of construction site
Drainage solutions for construction sites
(applicable to both surface runoff and groundwater) must be adopted before and
during construction of embankments and cuttings in order to facilitate
construction schedule and quality while preventing water damage to adjacent
residential areas.
- Prioritize construction of groundwater
drainage and treatment structures in design dossiers such as catch water
drains, drainage gutters, groundwater catchment drains, catchment toes that
prevent water from infiltrating the bottom of embankments on slopes, etc.
- If necessary, additional temporary drainage
structures shall be implemented to drain water from construction site and
prevent water from stagnating or infiltrating construction premise and causing
slope erosion.
- During construction process, each layer of
removed or deposited earth must have 2% to 4% in gradient (either lateral or
longitudinal) towards temporary gutters which extract water from construction
sites. Rainwater must not be collected into ponds on layers of embankments and
cuttings where construction is going on.
6.5.6. Determination of characteristic locations of
embankments and cuttings.
- Prior to construction, inspect each design
cross section in order to determine (via markers or posts) characteristic
locations of embankments and cuttings in practice so that shape and dimensions
of constructed embankments and cuttings in practice are compliant with those in
design. These locations consist of posts at the bottom of fill slopes, peak of
cut slopes, boundary of excavation pits, and radius in which excess soil is
dumped.
Markers or posts must be distinguishable and
protected throughout construction process. In respect of class I, class II
expressways, and areas with high embankments, deep cuttings, gap between two
markers shall not be greater than 50 m on a straight line and 10 m on a curve;
tolerance of markers may equal measurement accuracy level under 6.5.2.
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6.6. Tests for evaluating soil along the route and
fill materials collected from mines.
Requirements for this task are to evaluate
whether soil or materials of embankments, cuttings in practice along the route
are compliant with regulations under Article 5 then lead to appropriate
actions.
6.6.1. For all cutting sections where earth is removed
then deposited at embankments and mines where earth is removed the deposited,
sampling shall be conducted to examine parameters such as natural humidity, liquid
limit, plasticity limit, standard compactness, load-bearing capability, and expansion
via CBR tests. Where earth types mentioned under 5.1 and 5.2 are present,
examine for organic contents, soluble salt contents, and conduct tests to
determine name of soil group according to AASHTO M-145. Minimum sampling
density shall be 2 positions for each soil type of each section.
Where each section of embankment or soil mine
consists of multiple layers of soil with different types or different origin,
sampling and tests shall be conducted for each of those types.
6.6.2. In respect of soil at the bottom of embankments
and in subgrade of cuttings where design elevation has been reached, conduct
sampling and tests for parameters under 6.6.1. Minimum sampling density shall
be 2 positions for each km or 2 positions for each section of embankments or
cuttings with different soil types.
6.6.3. In all cases under 6.6.1 and 6.6.2, each
parameter is evaluated by mean value of 3 test samples.
6.7. Test construction phase.
6.7.1. Prior to regular construction, test
construction of a section of at least 100 m in length shall be conducted if:
- Earth embankments for expressways, class I
roads, class II roads, and class III roads;
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- Embankments or cuttings where new techniques,
technology, or materials are adopted;
- Sand embankments with blankets;
- Special embankments and cuttings (on weak
soils, in areas prone to landslide, on hard rock cuttings, on soft embankments,
etc.).
6.7.2. Test contents and requirements.
Test results must verify the following information:
+ Accurate components and indicators of
embankment and cutting construction materials.
+ Primary specifications of compaction
technology to be achieved during mass construction: Compaction sequence;
Combination and configurations of necessary
compactor machinery;
Material thickness prior to compaction;
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+ Quality control criteria and methods during
construction, especially for earth-rock embankments where guidelines under
Appendix C must be adhered to.
+ Construction technology and solutions (if
needed, adjustments to construction arrangement and schedule can be made).
7. Construction of
embankments
7.1. Collection of embankment earth (materials).
7.1.1. In addition to compliance with environmental
and natural scenery protection requirements under 4.7, production of embankment
materials shall be properly incorporated in local land planning and embankment
and cutting drainage planning (excavating earth from irrigation structures,
drainage structures for use as embankment materials); minimize expropriation of
paddy land; utilize barren, weathered earth; refrain from excavating earth
below groundwater level; commence excavation in a manner that does not affect
slope stability and embankment and cutting stability.
7.1.2. Excavation pits must not be located on either
side of expressways and on either end of bridges.
7.1.3. Prior to collection of embankment materials,
inspection for material characteristics must be conducted in accordance with
6.6 in order to determine whether the materials comply with requirements under
Article 5.
7.2. Processing of natural surface prior to
embankment construction.
7.2.1. Where lateral gradient of natural surface is
lower than 20%, organic earth layer must be removed after which the natural
surface is rolled to reach compactness K = 0,9 (for expressways, class I roads,
class II roads) or K = 0,85 (for other road classes) before embankment
materials are overlain on top.
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7.2.3. Solutions shall be taken to prevent water from
infiltrating the boundary between natural surface and the bottom of embankments
on hills.
7.2.4. Earth embankments must not be built directly on
top of natural surface that have at least 50% lateral gradient.
Where embankments are built on natural surface
with at least 50% lateral gradient with downhill supporting structures
(supporting walls of all kinds), handling of natural surface inside supporting
structures shall also be required to comply with 7.2.2 regardless of embankment
materials.
7.2.5. Where natural surface contains holes or
depressions, these cavities must be thoroughly emptied then filled by
appropriate materials under Article 5; embankments shall be laid in layers then
rolled to meet compactness requirements under 7.2.1.
7.2.6. Organic earth must be completely excavated then
removed and solutions must be taken to thoroughly drain water before
constructing embankments over paddy fields.
7.2.7. Approved solutions for treating natural surface
before construction of embankments shall be required for cases below:
- High embankments, rock embankments,
embankments of lightweight materials;
- Embankments that cross rivers, lakes or
encroach rivers, lakes, inundated areas;
- Embankments that cross areas with high
groundwater table or exposed groundwater veins;
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- Natural surface that has lateral gradient
above 50%;
- Natural surface at sections of special
embankments under 1.2 and Article 3;
- Embankment expansion in road upgrade and
renovation (solutions including treatment for natural surface and slopes of old
embankments in order to ensure adequate connection between old embankments and
renovated embankments and prevent the renovated embankments from sinking).
7.3. Laying and compacting.
7.3.1. Earth, rocks, or mix of earth and rocks of
different characteristics shall be laid in separate layers or road sections and
must not be mixed up with one another. Embankments shall be built from areas
with low elevation to areas with high elevation. Each horizontal layer must
consist of the same material type throughout its width; total length after compaction
of material layer of the same type should not be lower than 30 cm or at least
10 cm for the topmost layer.
Where soil with good permeability and soil with
poor permeability are used, soil with poor permeability must be laid first then
compacted to achieve 2% to 4% lateral gradient then topped by soil with good
permeability.
Soil with low CBR must be laid below that with
high CBR in a manner compliant with requirements in Schedule 3.
7.3.2. In case of earth and rock mix, solutions shall
be taken to evenly distribute rocks of 10 cm to 15 cm in dimension in each
layer.
7.3.3. Thickness of each layer before compaction
depends on compactor machinery and is determined via test construction in
accordance with 6.7.1 and 6.7.2.
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7.3.4. Prior to compaction, laid earth must have the optimal
humidity Wo corresponding to standard compaction results. Humidity tolerance is
± 2% relative to Wo. Where soil humidity is greater or lower than
the optimal humidity by 2%, dry the soil or water and stir up the soil
respectively; where embankments consist of sand, refrain from excessive
watering to prevent water from seeping into finished layers. Dry soil must not
be mixed with extremely moist soil.
7.3.5. Embankment construction machinery shall be
selected on the basis of embankment materials, construction characteristics
(large scale, small scale), terrain, embankment height, transportation
distance, schedule, and economic aspects (see Appendix A).
Schedule B.1 under Appendix B can be used as
reference for selection of compactor machinery. Heavy-duty vibratory roller of
15 tonne or higher is recommended to compact earth and rock mix layers.
7.3.6. Regardless of compactor machinery, the
following regulations must be adhered to:
- Embankments and cuttings must be evenly
compacted across their width over each work section from lower sections to
higher sections, from the sides of the road towards the centerline of the road for
straight sections, from inner curve to outer curve.
- Subsequent roller tracks must overlap by 15
cm to 20 cm; subsequent compactor marks must overlap at least 1/3 the width of
compactor marks.
7.3.7. Treating transition between construction
sections of embankments
Deposit soil to form a 30o slope
between construction sections of embankments or form transition steps between
embankment sections where step dimensions comply with 7.2.2.
Transition sections must be compacted where
construction of subsequent embankment section is commenced. Where steps are
built, each surface must be thoroughly compacted before further layers are
built on top of it.
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7.3.9. While depositing, adequate drainage compliant
with 6.5.5 must be assured.
7.3.10. Inspect quality of deposited layers during
construction
- Each layer of compacted soil must be examined
for compactness at at least 2 positions in 1000 m2 or less if the
layer does not make up 1000 m2; examination density can be increased
if necessary, compactness at positions close to slopes must be prioritized for
examination.
- Examination results must satisfy minimum
compactness K under Schedule 2 depending on position of examination. If
examination results do not satisfy minimum compactness K, either continue to
compact or excavate and compact again until examination results satisfy minimum
compactness K.
- Where examination method involves sand cones
or water bags, form a test pit that reaches to the bottom of the compacted
layer. Where examination method involves soil sample rings, the rings must be
inserted into the ground at the main depth, at the center of compacted layer. Where
examination method involves equipment that operates on physical mechanism, the
equipment must be operated and measurement sensor must be installed in
accordance with manufacturer’s written instructions attached to the equipment.
7.3.11. Inspection of compacted earth-rock mix during
construction
+ Where pebbles, rocks in earth are soft and
very soft with compression strength of 20 MPa or lower, inspection of compacted
earth quality shall be conducted in a similar manner to compacted earth under
7.3.10.
+ Where pebbles, rocks in earth are moderately
hard and very hard with compression strength greater than 20 MPa, inspection of
compacted earth quality shall be conducted as follows:
- Physical inspection (and written records) of
specifications of compaction technology must be conducting during construction
of each layer for thickness of deposited layer, humidity, order, number of
roller drives, compaction speed through a point by each equipment in machine
group; regular reminder must be issued so that compaction of each layer must be
compliant with tests for each type of earth-rock mix with known origin and
particle compositions. Failure to adhere to any element of approved compaction
technology during tests shall require the test to be restarted.
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∆H = Htr - Hs;
(1)
In respect of each cross section, ∆H must be
calculated for 5 to 10 points (depending on width of compacted layer) in order
to determine average ∆H of all measurement points representative to each cross
section. Throughout construction section, measure a cross section for every 20
m in length. Average ∆H of each cross section in a section must be greater than
or equal to the value of ∆H determined via tests; where average ∆H is lower
than the aforementioned ∆H value, further compaction is required until average
∆H is greater than or equal to the aforementioned ∆H value.
- In respect of important structures or in case
of suspicions relating to compaction quality, supervising consultant may
request re-examination of dry volume after construction of earth-rock mix layer
and compare with maximum dry volume attained corresponding to compaction
technology during previous site tests, where actual value is lower than test value,
additional compaction solutions must be adopted to achieve test values.
In this case, sampling and tests for
determination of dry volume and humidity at the scene shall comply with ASTM
D5030-04 (applicable to earth-rock mix where maximum particle dimensions are
greater than 125 mm) or ASTM D 4914-99 (applicable to earth-rock mix where Dmax
= 75 mm to 125 mm). Test positions and number of test positions shall be
designated by consultants and shall not be greater than 1 position for every 50
m of construction section.
Methods for establishing the aforementioned
criteria for compaction quality control via site test are provided for under
Appendix C.
+ In respect of earth-rock mix layers, in
addition to examination of compaction quality, visual inspection of the
following is also required:
- Compacted earth-rock layers must be
completely intact and without cracks (due to dislodged large rocks);
- Large rocks on surface layer are not easily
dislodged.
7.3.12. During construction of embankments, where
concerns pertaining to embankment materials are present via visual examination,
it is possible to collect sample to test for parameters under 6.6.1 and remove
materials that do not comply with requirements under Article 5.
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7.4.1. In order to guarantee compaction quality near
slopes, deposited width of each layer of embankments should be wider than
design width of either side by 15 cm to 20 cm.
7.4.2. Prior to slope reinforcement according to
design, shape of slopes (gradient and roughness) must be finished, slope
surface must be compacted again by compactor machinery at a rate of 3
times/point to 4 times/point where each point overlaps one another by at least
20 cm.
7.4.3. Inspect slope finishing quality at a cross
section every 20 m in length. Where gradient and roughness of slopes do not
satisfy requirements under Schedule 1, the slopes must be repaired in order to
satisfy requirements before reinforcement solutions are implemented.
In respect of earth-rock embankments, large
rocks must not be dislodged from embankment slopes (via visual inspection).
7.4.4. Where embankment slope is covered by a layer of
organic earth, this blanket layer must also be laid then compacted laterally
from the bottom of the slope to the top together with embankment layers on the
inner slope.
During construction, this blanket layer must
also undergo quality inspection similar to one applicable to embankment layers
of inner curve (see 7.3.10). Completion of slope shapes and quality inspection
of finishing quality during construction are required in the same manner
applicable to other earth embankment slopes.
7.4.5. Supporting structures for slope surfaces should
be constructed as soon as possible and in accordance with design dossiers and
quality control requirements during construction process.
7.5. Construction of sand embankments with blanketing
layers on both sides of slopes and at the peaks.
7.5.1. Blanketing materials shall conform to 5.5.
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7.5.3. Blanketing layers at the top of embankments
must be laid and compacted separately.
7.5.4. Solutions must be so taken during embankment
construction to prevent rainwater from infiltrating, collecting in sand
embankment. Temporary drainage groove or drainage buffer layers in form of
geotextile or drainage layer at the bottom of embankments shall be implemented
to drain water collected in sand embankments.
7.5.5. Requirements pertaining to quality and quality
inspection of embankment blanket construction shall be similar to those
applicable to embankment construction (7.3.10). Requirements pertaining to
quality and quality inspection of blanketed slope construction shall also
conform to 7.4.1, 7.4.2, and 7.4.3.
7.6. Construction of sections adjoining artificial
structures (bridge, culverts, walls, etc.).
7.6.1. Transition between bridge abutments or culverts
sides and adjacent embankments must at least be compliant with Figure 1; in
case of walls and other structures, transition embankment sections shall
conform to design drawings.
a. Bridge approaches
L=H+(3÷5)m where H
refers to height of embankment
b. Culvert sides (D: culvert clearance)
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Figure 1: Dimensions of
transition section
Materials with good drainage property and low
compressibility such as earth mixed with pebbles, sand mixed with chippings,
moderate-size and rough-size sand. Soil with poor drainage capability and fine
sand must not be used. Where other materials are not available, the
aforementioned materials must be reinforced by inorganic binders (at least 5%
cement or 10% lime). Weathered rocks and mix of different materials must not be
used as embankment materials. Fly ash, light materials, foamed concrete can be
used as long as research results are submitted and tests are conducted prior to
mass construction.
7.6.2. Prior to construction of subsequent transition
sections, waterproofing layers of abutments, walls, etc. and layers preventing
water extraction from sewers in the same vertical and horizontal drainage
system behind the structures according to design. The aforementioned concealed
work items must undergo commissioning and deemed satisfactory before embankment
construction is commenced.
7.6.3. In any case, construction of transition
embankments requires each layer to be laid then compacted from the bottom to
the top where thickness of a compacted layer should range from 10 cm to 20 cm
(even when heavy-duty roller is used). Where small compactor tools are used,
thickness of a compacted layer should be just below 10 cm.
Required compactness in transition embankment
sections must reach ≥ 0,98 for expressways, class I roads, and class II roads
and ≥ 0,95 for other road classes and must be greater than or equal to the
required compactness applicable to different elements of embankments and
cuttings under Schedule 2.
All sections must be adequately compacted,
including those adjoining structures’ sides. In respect of sections adjoining
structures’ sides, heavy-duty plate compactors capable of exerting a force
greater than 100 KN shall be employed or construction radius behind abutments
shall be extended to accommodate heavy-duty rammers; in respect of expressways
with large embankment or cutting width, heavy-duty rollers can be employed to
compact sections along the edge of abutments.
Sections where rollers or plate compactors
cannot be used, manually operated rammers shall be used.
Compaction quality inspection shall be
conducted for each layer in a manner compliant with 7.3.10.
7.6.4. Embankment construction of transition sections
and abutment sections shall take place simultaneously. Construction of
embankments in subgrade vicinity shall also be commenced at the same time as
that of the subgrade of adjacent transition.
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8. Construction of
cuttings
8.1. Excavation.
8.1.1. Excavation must be conducted in order, from the
top to the bottom, and in a manner that prevents wave-cut notches.
8.1.2. Solutions must be taken to ensure that slopes
where excavation work is ongoing are always stable. Caution must be taken when
excavation approaches slopes and design elevation in order to prevent excessive
excavation. Where soil is prone to erosion by rainwater, a layer of less than
20 cm in thickness should be reserved which will be removed in finishing
process (or just before construction of subgrade and pavement) to expose slopes
and design elevation.
8.1.3. Where actual terrain and geology conditions are
different from those in design during construction, changes pertaining to slope
gradient, slope stability solutions, position and dimensions of catch water
drain on slops must be promptly proposed. Proposed changes must be submitted
for approval in accordance with project management laws.
8.1.4. Where exposed groundwater layer or stream is
found during excavation, construction process must be suspended temporarily and
solutions must be proposed then submitted for approval. In the meantime, solutions
for temporarily draining water, directing groundwater away from construction
area, digging trenches to lower ground water and for preventing groundwater
from permeating or overflowing must be implemented.
8.1.5. Where design elevation is reached, collect soil
sample in subgrade vicinity for tests for parameters under 6.6.2 and 6.6.3 in
order to determine whether or not soil in the subgrade needs replacement.
8.1.6. Depending on terrain, topography conditions,
cross section of cuttings, transportation length, and transportation direction
of excavated soil, appropriate construction machinery and construction
solutions shall be selected. Construction machinery should be selected on the
basis of safe operating range and economic value (see schedule A-1 Appendix A).
The cutting section can be excavated simultaneously in each layer from the top
to the bottom of the entire section or individually in each part or over the
entire cross section. Selected construction solutions must include adequate
drainage conditions during excavation process in accordance with 6.5.5 and
facilitate operation of vehicles and machinery.
8.2. Construction of slopes of cuttings.
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8.2.2. Loose rocks on slopes must be immediately
removed.
8.2.3. Geometry and roughness of slopes must be
promptly examined in accordance with 8.2.1 and before reinforcement solutions
are adopted in accordance with requirements under Schedule 1. Cutting slopes
shall be inspected for finishing quality at a cross section every 20 m in
length.
8.2.4. Construction of supporting structures of
cutting slopes shall be commenced as soon as possible (including catch water
drains) and in a manner compliant with design dossiers and technical
instructions.
8.3. Waste soil dumping
8.3.1. Areas where waste soil is expected to be dumped
must be examined before construction to ensure that soil dumping does not
negatively affect scenery, the environment, or violate local land use planning
under 4.7.
Waste soil must not be dumped in cultivation
land, into rivers or streams that obstruct current or erode banks, slopes and
must not cause pollution.
8.3.2. Soil dumping must not be done in a way that
negatively affects stability of embankments and cuttings; soil must not be
dumped on slopes of embankments, natural slopes below cuttings in areas with
poor geological conditions, or areas with groundwater veins. Waste soil must
not be piled upon on road shoulder and on top of cuttings.
8.3.3. Waste soil dumping shall conform to regulations
below:
- Soil should be consolidated in designated
areas in order to prevent unauthorized dumping;
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8.4. Construction of drain gutters.
8.4.1. Centerline of drains must be determined from
the centerline of the road and identified by markers. Markers for boundary of
side drains are recommended.
8.4.2. Side drains should be smaller than design
dimensions initially. Side drains shall only be excavated to reach design
dimensions after finishing the embankments and cuttings (sweeping, curing the
surface, and leveling the shoulder). Drains must not encroach embankments and
cuttings or slopes thereof.
8.4.3. Soil excavated from side drains must not be
dumped on road shoulders. Soil excavated from catch water drains can be used to
form a berm at the toe of slope which must be carefully compacted to form a
slope gradient of 1:1,5 where the top surface is inclined towards catch water
drains with 2% to 4% gradient. Edge of berm slope must be at least 5 m away
from the top of cutting slope.
8.4.4. Gradient of catch water drains in all sections
should be less than 5%, if this gradient is greater than 3%, catch water drains
must be reinforced; water in catch water drains must not be directed to side
drains or collecting traps or sewer grates but must be directed towards upstream
that is at least 30 m away from sewer grates via sloped drains or stepped
drains.
8.4.5. Gutters and sloped drains, stepped drains must
be built out of stones; plaster must not be greater than 40 mm in thickness and
must consist of full mortar.
8.4.6. Sloped drains and stepped drains of cement
concrete should be divided into segments of 2,5 m to 5 m in length while those
of stones should be divided into segments of 5 m to 10 m for construction
purposes and gaps between segments must be sealed by waterproofing materials.
8.4.7. Side berms of side drains must be parallel to
centerline of the road. Side berms of all drains on straight sections must be
straight; on curved sections must be gradually curved, must not be corrugated
or changing direction unexpectedly; especially for sections that joining other
drainage structures, drain direction and edges must be connected smoothly.
8.4.8. Before and after reinforcing drains according
to design, geometry elements must be examined. Construction quality and
tolerance must be inspected in accordance with Schedule 1.
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9.1. Construction of half-embankments and
half-cuttings
9.1.1. Construction of cuttings shall only be
commenced after handling natural base below embankments in accordance with 7.2.
Excavated soil that satisfies requirements for embankment materials under
Article 5 can be used as embankment materials, laid then compacted in
individual layers from bottom to the top.
9.1.2. Construction of embankment and cutting sections
shall also be required to adhere to Article 7 and Article 8.
9.1.3. Solutions for ensuring equal load distribution
in subgrade of embankments and cuttings must be taken. If necessary, soil in
subgrade of cuttings must be replaced in order to stay in line with that in
subgrade of embankments.
9.2. Construction of renovated, upgraded, expanded
road base
9.2.1. Rely on design drawings to clear old kerbs and
shoulders, equipment, signaling devices, and protection devices on expanded
sides of road base; in respect of built drains, built blocks must be
demolished, old materials must be scraped, new soil is then laid and compacted
to required compactness.
Where old side drains are to be filled up,
temporary drains must be built to drain water without affecting traffic on
existing roads.
9.2.2. Prior to construction, temporary structures
must be built to prevent water from entering excavation or embankment
construction areas.
9.2.3. Treatment for expanded embankments shall
conform to design dossiers and regulations under 7.2.
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9.2.5. The bottommost layer of expanded section should
utilize a buffer layer of 30 cm in thickness consisting of gravels, sand, or
chippings. Where expanded embankments is inundated or has poor geological
conditions, actions must be taken in accordance with design.
9.2.6. Expanded embankment materials should be
identical to materials of old embankments or materials with low
compressibility.
9.2.7. Construction of expanded embankment sections
shall conform to Article 8.
9.2.8. Where road is in use during renovation,
upgrade, and expansion, control and limiting solutions must be taken to ensure
coherent, safe traffic and facilitate construction work. Solutions must be
taken to prevent loose soil on roads in use and limiting duration in which
vehicles operate on newly built road base during rain seasons.
9.2.9. Where existing pavement must be lowered or
raised, regulations below must be adhered to:
- Thickness of soil layer in-between old
pavement and new pavement must not be lower than 50 cm.
- Excavated materials of old pavement can be
used as embankment materials where appropriate as long as design consultant
approves.
10. Construction of
slope protection and reinforcement work items
10.1. General provisions
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10.1.2. Prior to construction, design must be
cross-checked against topography, geology, hydrography conditions so that
timely changes to reinforcement and protection solutions can be proposed if
necessary.
10.2. Planting trees and vegetation to prevent slope
erosion
10.2.1. Cultivar and type appropriate to local weather
and conditions shall be selected. Trees and vegetation must be tended to until
maturity (watering, fertilizer, etc.). Water for trees and vegetation must not
include grease, oil, acidic or basic substances.
10.2.2. Where grass is planted by sowing, till the
soil, spread seed evenly, and take actions to prevent seeds from being carried
away by rainwater where seed quantities are approximately 200 g for every 100 m2.
Where grass is planted via patches, thickness of lower patch shall be 5 cm to
10 cm while thickness of grass patch shall be 20 cm to 30 cm. Prior to
placement of grass patches, slopes must be scraped by 3 cm to 5 cm deep at
which point patches are secured to the slopes via bamboo nails of 15 cm to 20
cm in length.
Patches can be so arranged to stay parallel to
edges of the road, gap between centerlines of patches shall be approximately
1,5 times the width of the patches. Patches can also be arranged into squares
that are at a 45o angle from the edge of the roads where each square
is 1,2 m x 1,2 m in dimensions and gap between centers of the squares shall be
1,4 m.
10.2.3. Planting and care for trees, vegetation, and
grass planting that utilizes special techniques (spraying seed mechanically,
planting in geotextile cages, etc. or spraying seedlings on patches on slopes)
shall conform to design instructions.
10.2.4. Trees and grass shall be planted from the
bottom to the top of slopes; trees on cutting slopes should be at least 1 m
taller than the top of the slopes.
10.2.5. Inspect tree and grass quality
- Wilted trees and and grass must not exceed
10% total area and patches of wilted trees and grass must not be larger than 1
m2;
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- Inspection shall be conducted after 6 months
from the date on which the trees and grass are planted; where the
aforementioned requirements are not met, additional planting is required;
- Trees and grass planted in concrete frames or
rock blocks that reinforce slopes shall also be inspected in accordance with
the aforementioned criteria.
10.3. Construction of protected layers in form of
rock arrangement or constructed on cast cement blocks
10.3.1. Hard rocks with compression strength greater
than 40 MPa (in case of cement concrete, compression strength greater than 20
MPa) must be used; rocks that are undergoing weathering process must be
avoided. Structures of protective layers (toes of slopes, buffer layers, etc.)
must be compliant with design.
10.3.2. Protective layers that have been installed
manually shall require foundation to be built with plaster, especially
protective layers of slopes of cuttings with side drains at the slope toes.
10.3.3. Gaps of manually placed rocks must be in
alternating order and tightly sealed by chippings.
10.3.4. Plaster intensity shall be compliant with
design requirements.
10.3.5. Placement of construction stones or cement
concrete slabs must be concluded before plaster is set and must be maintained
(by watering) as soon as the plaster is set.
Gaps filled by plaster must be alternating in
order and full mortar.
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10.3.7. Laid stone or concrete must leave room for expansion
joints and depression that are 10 m to 15 m between them and gap of joints is
20 mm to 30 mm. Drains shall be provided in accordance with design drawings.
10.3.8. In respect of slope sections prone to
inundation, toes of protective layers must be placed at a minimum depth 1 m
below the elevation at which erosion takes place. Where foundation excavation
reveals poor geological conditions or geological conditions differing from
those in design drawings, solutions must be proposed.
Following foundation construction and
commissioning, embankments must be rebuilt using materials according to design
requirements.
10.3.9. Construction quality inspection
- Laid or built surfaces must be even. All
joints must not contain gaps and must be alternating in order, tightly packed,
and full mortar. All individual rocks must make contact with slopes and must
not be stacked on top of each other;
- Method for examination and quality of
manually laid rock layer shall conform Schedule 4; method for examination and
quality of cement concrete layer shall conform to Schedule 5.
Schedule 4: Method for
examination and quality standard of manually laid layer
Details of test
Tolerance relative to
design
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Thickness of protective layer
± 50 mm
Inspect 4 random positions in 100 m2
Elevation of surface of protective layer
± 30 mm
Insect 5 random points over a stretch of 20 m
using an optical level
Roughness of protective layer
50 mm (gap when
measured by 2 m straight edge)
Inspect 5 positions every 20 m
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Details of test
Tolerance relative to
design
Examination method
Mortar intensity
Not lower than design value
Collect 2 sample groups per construction
shift for test
Elevation
Top part
± 20 mm
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Bottom part
- 20 mm
Dimensions on cross section of protective
layer
± 30 mm
Measures 5 random points every 20 m in length
Roughness of protective layer
30 mm (gap when measured by 2 m straight
edge)
Measure 5 random points using a 2 m straight
edge over a stretch of 20 m
10.4. Construction of slope protection by rock piling
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10.4.2. Gradient of rock slopes must be less steep that
natural resting gradient of wet rock. Thickness of protective layer shall not
be lower than twofold the largest rock size.
10.4.3. Construction should take place during dry
seasons. Rocks of smaller sizes should be laid in-between rocks of larger
sizes.
10.4.4. Construction quality inspection:
- Rock size and type shall conform to design.
- Location and area where rocks are laid shall
conform to design (with tolerance of -20 cm relative to design), top elevation
for rock laying must not be lower than design, gradient of rock pile must not
be steeper than design value.
10.5. Construction of walls and other supporting
structures.
Construction of these structures require
compliance with technical guidelines under design dossiers (including
examination methods and indicators for construction quality inspection).
11. Safety and
environmental protection in construction of embankments and cuttings
11.1. General provisions
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11.1.2. Occupational safety measures must be based on
applicable legislative documents on health protection, fire safety, and
epidemic prevention. Solutions for minimizing negative environmental impact
must be based on environmental impact assessment report compliant with
applicable legislative documents for relevant construction stages of projects; especially
surveying of subsurface pipes, electric cables, and optic cables in construction
vicinity.
11.1.3. Coherent and visible warning signs must be
installed to inform construction personnel, local inhabitants, and people in
the area.
11.2. Construction safety measures.
11.2.1. Lighting shall be required if construction
takes place at night. Where common electrical network is used, regulations of
electricity sector must be adhered to.
11.2.2. During construction of temporary roads and
temporary bridges, installation of warning signs or assignment of traffic
coordinators shall be required.
11.2.3. Construction personnel must have undergone
training pertaining to occupational safety rules relevant to their tasks and
must wear PPE upon entering construction sites. Personnel working with
machinery must avoid working within range of active machinery.
11.2.4. Separation distance must be maintained between
simultaneously active construction machinery. Machinery must not be positioned
near ditches, holes, edges of slopes, and areas with unstable foundation.
11.2.5. Machinery shall only be allowed to excavate at
a distance away from artificial structures that is sufficient to maintain
structural safety. Where machinery excavates near these structures, warning
signs must be erected.
11.2.6. Excavation of foundation or drainage gutters
must employ solutions for maintaining stability (either via slopes or
supporting beams, etc.) depending on topography, hydrography conditions and
excavation depth. Where bottom section of slope toes or natural slope topes are
excavated, excavation shall be carried out in individual sections where a
section is excavated and foundation is laid or a section is excavated for
placement of trenches and drainpipes then filled before other work on other
section is commenced. Where deep excavation is conducted, warning signs and
protective barriers must be installed and conditions of excavation shores must
be monitored for timely actions; soil excavated for foundation construction
must be dumped in a way that does not affect excavation shore stability.
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11.2.8. Conveyor equipment of all types or hoisting
equipment for transportation of rocks shall be used, operated by professional
personnel, shall not be overloaded, and shall not be used for human
transportation.
During rock transportation, working personnel must
not be standing or sitting below hoisting equipment.
11.2.9. During construction of slope protective layers,
all personnel shall be prohibited from walking on newly built slope surfaces;
rocks, materials, and equipment must not be rolled down from heights.
11.2.10. Where plaster sprayers or gas
compressors are used, pressure gauge must be regularly monitored so that
de-energization is performed promptly in case of irregular increase or decrease
in pressure.
11.2.11. Where construction of embankments and
cuttings require blasting, blasting design and blasting passport shall be
required (placement of explosives on contour maps, type of explosives,
detonation methods, detonation time, safety distance for involved personnel,
constructions, and residential areas, other instructions pertaining to response
to possible scenarios during blasting). Blasting shall be required to be
compliant with regulations below:
- Professional personnel must undergo training.
Involved personnel must be assigned with specific tasks and responsibilities.
- Warning and instructions shall be provided
for construction sites and adjacent residential areas, areas with foot traffic
shall be required to be stationed by assigned personnel and protective
barriers.
- Prior to detonation, specialized personnel
shall be required to inspect construction of detonation network.
- Personnel engaged in work related to
preservation, transportation, installation, and detonation must not wear
clothes that can create static.
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- Blast holes must not be placed in line with
walkways, electrical paths, and adjacent structures. Explosives must not be
planted at unexploded blast holes.
- Upon detonation, count the number of
explosion relative to the number of planted blast holes. In case of duds,
instructions under blasting passport must be adhered to.
- Blasting shall not be conducted during
nighttime; work process must be temporarily suspended and involved personnel
must exit work area in the rain or lightning storm.
- Planted mines must be detonated in the same
working shift.
- Following detonation, caution must be taken in
clearing debris. Where dud mines or rocks in a position where they can roll
downhill are detected, timely report and warning installation shall be
required.
11.3. Environmental protection.
11.3.1. Prevention of soil and water pollution and soil
erosion:
- Use period of land used for construction must
be limited or shortened.
- Soil, sand, rock must not be gathered without
permission in accordance with 4.7 and from areas where current causes land
erosion.
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- Wastes, domestic wastes shall be disposed of
and buried at locations permitted by local authorities during construction,
especially waste mixed with grease and oil.
11.3.2. Prevention of emission and noise pollution.
- Solutions for limiting noises and vibration
caused by construction process must be adopted.
- Working personnel must be outfitted with
noise-cancelling equipment.
- Solutions for limiting dust and emission of
construction vehicles and machinery and during transportation of soil and
materials shall be adopted, especially solutions for limiting loose soil during
transportation.
- Consolidation yards for soil and materials
shall be located downwind from residential areas.
11.3.3. Ecosystem protection.
- Solutions for protecting rare plants must be
implemented prior to construction.
- Non-permitted tree felling and game hunting
shall be prohibited during construction.
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- Construction of embankments and cuttings that
cut through forests or areas with dense trees must accompanied by wildfire
prevention and forest protection solutions as per the law.
11.3.4. Protection of cultural heritage
Regulations under 4.8 must be adhered to.
12. Inspecting and
commissioning.
12.1. Inspection before construction.
12.1.1. Prior to construction, all details under
Article 6 must be examined; unsatisfactory details must be fulfilled before
construction commences.
12.1.2. Inspection of accuracy of route direction must
be prioritized following restoration (6.5.1 and 6.5.2), accuracy of
characteristic points of embankments and cuttings under 6.5.6. Inspection shall
be carried out using regular measuring instruments at all cross sections in
detail construction drawings.
12.1.3. Inspection of soil and construction materials
of embankments and cuttings shall conform to 6.6
12.2. Inspection during construction.
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+ Inspection of collection of filling soil and
conformity of filling materials in accordance with 7.1, including embankment
sections adjacent to artificial structures in case of sand surface with
blanketing layers and in case of earth-rock fill embankments. Embankment
materials are usually examined at the source in accordance with 7.1.3. However,
where suspicions are raised following laying and compacting, re-examination can
be conducted on the basis of 7.3.12, in this case, samples and inspection
parameters can be increased if necessary.
+ Inspect treatment quality of natural surface
before building embankment in accordance with 7.2.
- Examine the excavation of organic layer
extensively.
- Examine step formation (7.2.2 and 7.3.7):
Randomly examine step dimensions at suspicious areas and, if necessary, make
steps and compact step surfaces again.
- Examine compactness of natural surface
(7.2.1), compactness of steps, and compactness of compensatory layer under
7.2.5.
- Examine in accordance with technical
guidelines under design dossiers for cases under 7.2.7.
+ Examine embankment quality in accordance with
7.3.10 for earth embankment and in accordance with 7.3.11 for earth-rock mix
embankment. As embankment quality inspection is usually only conducted during
construction and for each layer of embankment, all inspection record of each
layer must be incorporated in commissioning dossiers.
+ Examine quality of embankment slop in
accordance with 7.4.
12.2.2. Inspection of cutting quality.
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- Examine quality of cutting slope in
accordance with 8.2.
- Examine soil dumping in accordance with 8.3.
12.2.3. Examine gutter construction quality and gutter
reinforcement quality in accordance with 8.4.8 combined with visual inspection
and measurement using straight edge in accordance with 8.4.4, 8.4.5, and 8.4.6.
12.2.4. Examine reinforcement quality of slopes which
is usually compliant with 10.2, 10.3.1, and 10.4.4.
12.2.5. During construction, regularly examine
construction safety and limit negative environmental impact caused by
construction process on the basis of Article 11.
12.3. Examine and conduct commissioning of completion
of embankments and cuttings.
12.3.1. Following completion of a section of
embankments and cuttings and prior to commissioning of the section, restore
position of all routes and primary elevation markers to facilitate measurement,
commissioning, and further construction work. Route restoration shall conform
to 6.5.1 where restored points on straight sections can be increased to 50 m.
12.3.2. Prior to commissioning, contractors must:
- Inspect quality of construction work items at
their discretion in accordance with 12.2 in order to rectify defects. Where
compensating filling is required, thickness of compensating layer must be at
least 10 cm (where required thickness is lower than 10 cm, till the layer below
until compensating layer is 10 cm in thickness). Compensating section must be
properly connected to existing section. Conduct visual inspection to verify
whether transition of completed sections is smoothly, even, and not broken.
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- Clear construction site in accordance with
Article 4, 11.3.1 and waste soil piles in accordance with 8.3.1.
12.3.3. Inspection that serves commissioning of a
section of embankments and cuttings shall be conducted as follows:
- Examine dossiers filed during construction.
- Examine geometry elements in accordance with
Schedule 1
- Examine quality of trees and grass planted on
slopes in accordance with 10.2.5 and protective layers laid manually or built
with mortar in accordance with 10.3.9.
Where examination results indicate
unsatisfactory details, request contractors to revise and repair until such
details are satisfactory then file commissioning dossiers.
12.3.4. Where quality of embankment materials or
quality of compaction or quality of concealed work items is suspected,
commissioning may repeat other examination that has been conducted during
construction in accordance with 12.2 as long as project developers or other
competent authorities approve.
12.4. Examination and commissioning of special
structures.
In respect of structures or work items of
embankments and cuttings that are not regulated by this document, inspection
and commissioning in all steps must conform to technical guidelines under
design dossiers.
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APPENDIX
A
(Reference)
SELECTION
OF CONSTRUCTION MACHINERY FOR EXCAVATING AND FILLING EARTH
Schedule A.1: Scope of
use of primary machinery
Type of machine
Scope of use
Preparation
Excavation and
filling
Other tasks
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- Making temporary road.
- Felling tree, clearing stump.
- Clearing grass, removing organic layer.
- Leveling or making ramp.
- Filling lake, canal, trench.
- Making step on slope.
- Excavating and transporting earth below 120
m.
- Excavating and filling earth to a height
below 3,5 m.
- Preliminarily leveling and compacting laid
soil (*)
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- Towing immobile machinery and vehicle.
Excavator of all kinds
- Forming temporary road (reversed-bucket
excavator).
- Excavating and filling earth within from 5
m to 10 m (or loading onto transport vehicle).
- Digging trench.
- Excavating underwater (rope shovel).
- Dredging mud.
Wheel loader
- Clearing grass.
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- Excavating and relocating soil (over
appropriate distance from 100 m to 1000 m depending on bucket volume).
- Laying then compacting soil.
- Preliminarily compacting after excavating.
Self-propelled grader
- Clearing grass.
- Removing organic soil.
- Forming step.
- Collecting soil from pit to form step below
75 cm in height.
- Excavating cutting below 60 cm in depth.
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- Digging drain gutter.
- Leveling, creating camber gradient.
Cultivator
- Tilling old surface.
- Felling tree, clearing stump, clearing
small tree.
- Tilling hard soil in advance to facilitate
operation of other excavators.
(*) This usage does not extensively utilize
machine capacity and is such not economical
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(Reference)
SELECTION
OF COMPACTOR MACHINERY FOR EMBANKMENTS AND CUTTINGS
B I. Depending on type of soil, it is possible
to consult combination of compactor machinery for construction of highway
embankments and cuttings under Schedule B.1 below:
Schedule B.1: Selection
of compactor machinery dependent on compacted materials
Type of compacted
materials
Type of compactor machinery
Fine grain soil
Sandy soil
Gravel soil
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Scope of use
Smooth two-drum roller: 6 tonne to 8 tonne
+
+
+
+
Use drum roller to create preliminary
evenness
Smooth three-drum roller: 12 tonne to 18
tonne
+
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+
-
Use regularly
Tyred roller: 25 tonne to 50 tonne
+
+
+
+
Use regularly
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+
-
o
o
Use for sand mixed with clay, dust
Vibratory drum roller
-
+
+
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Use regularly
Vibratory padfoot drum roller
+
+
+
+
Use commonly for fine grain soil with high
humidity
Hand-guided vibratory drum roller
-
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+
o
Use in narrow sections
Impact compactor
-
+
+
-
Use in narrow sections; heavy-duty impact
compactor ≥ 800 kg is reserved for coarse soil
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+
+
+
-
Use in narrow section
Bulldozer, wheel loader
+
+
+
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Use to level and compact roughly
NOTE:
1. Symbols in each field are interpreted as
follows:
+ practical; - not practical but usable; o:
impractical
2. Name of soil type corresponds to
classification under TCVN 5729:2012
3. Where sheepfoot drum roller, vibratory
drum roller, vibratory padfoot drum roller is used, smooth drum roller must
also be used in conjunction
B II. Thickness of laid soil layer before
compaction corresponding to type of roller (for reference)
- Sheepfoot drum roller of 6 tonne to 8 tonne:
≤ 30 cm
- Impact compactor of 10 tonne to 12 tonne: ≤
40 cm
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- Smooth drum roller of 8 tonne to 12 tonne: 20
cm to 25 cm
- Smooth drum roller of 12 tonne to 15 tonne:
25 cm to 30 cm
- Tyred roller of 12 tonne to 20 tonne: 20 cm
to 30 cm
- Tyred roller of 40 tonne to 50 tonne: 50 cm
to 60 cm
- Hand-guided impact compactor: 20 cm
- Manual impact compactor: ≤ 20 cm
APPENDIX
C
(Regulations)
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C I. Principles.
In this Standard, quality inspection of
compaction of earth-rock mix primarily relies on maximum dry mass per unit
volume (compactness) Smax that can be achieved via practically
available combination of compaction machinery and technology adopted on a
section of test construction. This means the value of Smax
determined onsite according to the above will be used instead of standard compactness
derived from laboratory compaction tests. On-site compactness Smax will vary
depending on origin, particulate components of earth-rock mix, combination of
compactor machinery, laid thickness, humidity, compaction capacity (number of
operations of compactor), and drum roller speed. On the basis of correlation
between Smax and variables above at the end of test construction, parameters
distinct to selected compaction technology and another indirect parameter which
is reduction to compacted thickness ΔH shall be introduced to control
compaction process and conduct compaction quality inspection and commissioning
in accordance with 7.3.11.
C II. Determination of standard onsite
compactness Smax.
Procedures:
1. Choose appropriate and practically available
impact compactor: In addition to light drum roller, medium drum roller, and
finish drum roller, primary drum roller should be vibratory roller of 15 tonne
or higher in weight (or the heaviest possible vibratory roller).
2. Lay materials for test and arrange section for
test construction.
a. Composition and origin of earth-rock mix
must be identical to those for mass fill.
b. Materials laid for testing should be laid
with at least 2 different thickness values.
- A thickness value corresponding to the
minimum thickness of 1,65 to 1,8 times the maximum grain size Dmax
in embankment materials (so that compacted thickness is around 1,5Dmax).
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- Each thickness value shall be so arranged to
have at least 3 humidity values which range from 0,95 Wo to 1,05 Wo
where Wo is the best humidity of embankment materials after eliminating
particle larger than 19 mm (standard compaction test using large compactor in
laboratory compliant with 22 TCN 333-06).
- Laying of materials shall be compliant with
7.3.2. As a result, each section of test construction shall consist of at least
6 smaller sections.
NOTE: Arrangement of test section may consist
of multiple shorter sections (decided entirely by consultant) depending on
practical conditions (allowing for more variations of thickness and humidity).
3. Design grading layout plan, grading procedures
and speed.
a. Rely on 7.3 to develop design, including
preliminary grading, primary grading, and finish grading.
b. The speed at which primary grade is limited
to under 4 km/h.
c. Laying and compacting guidelines shall be
devised for test construction (requirements must be described in details).
4. Conduct test construction and sampling.
a. Lay and compact in accordance with drafted
technical guidelines.
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c. Following preliminary grading and before
primary grading, measure elevation of compacted layer; following primary grading
of 6 times/position and 8 times/position and 10 times/position ,etc., measure
surface elevation at the same position to determine reduction in thickness ΔH
in accordance with 7.3.11 and determine average ΔH of inspected cross section.
5. Choose standard on-site compactness Smax.
On the basis of test results, draw graphs
depicting changes to dry mass per unit volume relative to number of roller
operations and humidity corresponding to each thickness of test layers in order
to indicate a gradual increase of compactness corresponding to the increase in
number of roller operation so as to determine the most advantageous compacting technology.
However, the highest dry mass per unit volume in the entire result group is
selected as standard o-site compactness Smax. This value is the
highest compactness achievable in practical conditions by practically available
machine group and most appropriate compaction technology.
6. Determine other inspection parameters.
a. Specifications of corresponding compaction
technology will be determined via Smax: laid thickness prior to
compaction, humidity during compaction, number of roller operation, and the
speed at which grading is commenced (especially primary grading). At the same
time, determine reduction to thickness ΔH corresponding to each cross section
which are parameters for controlling and inspecting compaction quality of each
layer.
b. It is possible to derive at different
compaction technology parameters as long as all Smax values are
approximately equal (such as the case where a thinner layer is graded less
frequently will result in Smax that is roughly equal to the case
where a thicker layer is graded more frequently, or compaction effectiveness
can be higher in appropriate humidity). In this case, a more economical
compaction technology can be selected for mass construction.
All Smax values are considered
approximately equal if they deviate from one another by no more than 0,02 Smax.
c. Where equipment and correlations are
sufficiently reliable, examine whether CBR of compacted earth-rock mix layer
meets Smax via on-site tests such as measuring on-site CBR in order
to extrapolate corresponding CBR. Where CBR measurement satisfies Schedule 3,
selection of Smax as standard compactness will have a better basis.
7. Draft technology procedures for compacting
earth-rock mix for official application in mass construction. The procedures
must include parameters of applied compaction technology, criteria for close
control during construction and quality inspection parameters following
compaction of each layer.
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During initial application in mass
construction, examination must be conducted for adequacy and conformity of
compaction procedures by carrying out tests for determining dry mass per unit
volume by ASTM above after compacting a layer according to the procedure and
compare attained results with Smax determined via test construction.
Where the deviation among the values is greater than 0,02 Smax, look
into causes and make necessary adjustment to the procedures.
APPENDIX
D
(Regulations)
TEST
METHOD FOR DETERMINING TOTAL SOLUBLE SALT CONTENT IN SOIL.
D.1. Principles
D.1.1. When distilling filtered solution
(prepared in accordance with D.1.2), all soluble salts will crystallize then be
dried at 100 oC - 105 oC and weighed in order to
determine total soluble salt contents in soil.
D.1.2. Preparing filtered solution
1. Measure 200 g of soil (soil that has been
grounded and passed through a sieve of 1 mm clearance, cleared of tree roots
and organic matters, dried at 105 oC then let cool in room
temperature) and place in a 500 ml glass bottle with small opening.
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D.2. Test equipment and chemicals
D.2.1. Test equipment
1. 50 ml beaker
2. 50 ml pipette
3. Desiccator
4. Drying oven
5. Scale with ± 0,0002 g accuracy
D.2.2 Chemicals
10% H2O2 solution and
distilled water. Distilled water must be pure and not containing Cl-,
Ca+, Fe+++, Mg++.
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D.3.1. Add 50 ml (or 25 ml) or filtered
solution (under D.1.2) to the beaker (with known mass). Place the beaker on the
double boiler and turn on the double boiler until the beaker content is dry. Where
the residue is yellow or black in color, this means the soil contains soluble
organic matter. In which case, add drops of 10% H2O2 to
moist the soil sample evenly before drying it again. Where residue is white,
stop adding H2O2.
D.3.2. Place beaker into drying oven and dry at
100 oC - 105 oC for 1 to 2 hours and let cool at room
temperature in desiccator then weigh sample.
Then continue to dry at 100 oC - 105
oC for 0,5 h, let cool, and weigh until sample mass no longer
changes.
D.4. Calculation of total soluble contents in
soil A via formula (2)
g/100g of dry soil (2)
Where:
G0: mass of empty beaker (g);
G1: mass of beaker and dried residue
(g);
G: mass of original soil sample (g);
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V1: volume of filtered solution for
test (ml);
K: dry factor of soil determined by (3).
(3)
Where:
W (%) means humidity of cool soil sample in
room temperature (humidity of dry soil). This humidity is determined from soil
sample before it is added to glass bottle under Point 1 of D.1.2.
TABLE OF CONTENTS
Foreword
1. Scope
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3. Terms and definitions
4. General requirements
5. Materials of embankments and cuttings
6. Embankments and cuttings construction
preparation
7. Construction of embankments
8. Construction of cuttings
9. Construction of half-embankments,
half-cuttings and renovated, upgraded, expanded embankments and cuttings
10. Construction of slope protection and
reinforcement work items
11. Safety and environmental protection in
construction of embankments and cuttings
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Appendix A - (Reference) - Selection of earth
excavating and filling machinery
Appendix B - (Reference) - Selection of
compactor machinery
Appendix C - (Regulation) - Methods for
establishing compaction quality control parameters for earth-rock mix layer via
test construction section
Appendix D - (Regulation) - Test method for
determining total soluble salt content in soil