SECURITY AND SAFENESS VRAMP – CONTRACT PACKAGE RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA EMBANKMENT TABLE OF CONTENTS I CONSTRUCTION OF EMBANKMENT II COMMON EMBANKMENT I CONSTRUCTION OF[.]
VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA EMBANKMENT PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA TABLE OF CONTENTS I CONSTRUCTION OF EMBANKMENT II COMMON EMBANKMENT PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA I CONSTRUCTION OF EMBANKMENT Construction sequences Setting out, staking, site clearing and grubbing Excavating unsuitable soil, drainage ditches Construction of embankment with desity K95, CBR ≥ 5% Construction of embankment with density class, CBR ≥ 8% Site clearance and soil excavation Carry out the setting work and staking of each cross section as the approved construction method statement, mark the locations, limiting the areas to clear trees, cut grasses, excavate roots of trees, remove away debris and then submit the Engineer for approval before conducting the next work Using the measures to ensure effective safety and warnings for the areas of construction and arrange lights at night if necessary Any debris shall be removed or buried in the right places accepted by the Engineer and the Employer within the range of the project and filled up at least 30cm above to create the shape and visible slope The lower architecture of the old works (if no other requirements), which needs to be destroyed up to the natural stream bottom, the other structures outside the range of natural water flow will be excavated to at least 50cm below the natural soil surface Besides the "excavation and relocation of works and obstacles" will comply with all the provisions of the technical instructions Gathering the materials: gathering materials for construction of embankment Entrance to the site: Gathering the material for embankment is expected to complete by road transportation It is expected to supply clay material at the quarries in the surrounding area to ensure requirements under the technical specification that are approved by the Engineer and the Employer Excavation of organic soil and unsuitable soil The excavation of organic soil and unsuitable soil and part of weak soil of the embankment (at the positions, where sliding stability are not guaranteed) shall be conducted immediately after the completion of the site clearance The contractor will use bulldozers and excavators to execute at the soft soil and mud areas During the excavation, the attention is paid to keep excavated ground always dry, well drained, take measures to prevent water flow into the bottom of the excavated ground (diversion of water flow and clearing drainage) Excavator used in combination with labors to level and make slope of the embankment, size of each level shall be followed as design, ensuring good contact between the new and existing embankment PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA All excavated materials will be transported and hauled away by trucks to dumping area or landfill areas, which are permitted by the Employer and the Engineer, the reused material must be gathered at the right place, piled, creating slope for good drainage, and does not affect the surrounding environment After excavating to the bottom elevation of the new roadway embankment, sending request for inspection to the Engineer for his inspection and acceptance of the work, then move to the next work items II COMMON EMBANKMENT Material requirements 1.1 Submittal of materials The Contractor shall submit the construction method statement of the roadway embankment including all construction drawings and complete construction schedule on the use of materials for roadway embankment to the Engineer for approval Contractor shall ensure that all borrow pits have full licenses and approval of competent authority for its operations and exploring Information support for the supply of the material for embankment may include but without limitation to the following information: - The positions of borrow pit, delivery process to the construction site - Expected volume of material will be provided by each borrow pit - Making the safety measures and other environmental management measures and traffic management The Contractor shall submit the Engineer the material testing sample corresponding to each type of material provided for incorporation as material for embankment 1.2 Embankment Embankment shall be constructed of borrow materials, excavated earth or rock or other materials, approved by the Engineer as suitable for use in the permanent work Materials will also be selected preferentially in accordance with Vietnam Standard TCVN 4447-87, TCVN 5747 -93 Rock material shall not be used as backfill around pipes nor in the 30 cm of fill directly beneath subgrade For backfill and fill material used in these locations the maximum stone size shall not exceed 10 cm The particular requirements for Common Embankment: - 1.3 CBR strength: Minimum soaked CBR of 5% in according with 22TCN 322-06 at 95% of modified maximum dry density Sand for Common Embankment If sand for common embankment is specified on the Drawings, such materials shall consist of river or pit-run sand whose properties shall comply with as the following requirements: PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA For Common Embankment - CBR strength: Minimum soaked CBR of 10% in accordance with 22 TCN 332 06 at 95% of modified maximum dry density in accordance with 22 TCN 332 – 06 - Plasticity: Material shall be non-plastic and free from clay lumps - Gradation: Maximum nominal particle size 10mm Material finer than 0.075mm sieve: 25% maximum Construction steps 2.1 Site preparation All unsuitable materials, which can cause damage to the roadway embankment, will be removed from the range of construction prior to commencement of the work Prior to construction of the roadway embankments, all necessary surface drainage, clearing and grubbing in that area shall have been performed in conformity with the Specification Embankment construction shall consist of: - Constructing roadway embankments, including preparation of the area upon which they are to be placed; - The construction of dykes within or adjacent to the roadway, - The placing and compacting of approved material within roadway areas where unsuitable material has been removed; and - The placing and compacting of embankment material in holes, pits, and other depressions within the roadway area In locations indicated on the Drawings the embankment slopes shall be covered with Cohesive Slope Material to prevent erosion Embankments and backfills shall contain no muck, peat, sod, roots or other deleterious matter Rocks, broken concrete or other solid, bulky materials shall not be placed in embankment areas where piling is to be placed or driven 2.2 Methods of Construction: Using dump trucks 10T to gather sand to the location of the construction, sand shall be placed into each pile, the distance between the piles shall be calculated carefully so as to ensure sufficient thickness of embankment after compacting and not consume more labor for leveling Checking sand moisture before filling of each layer for the embankment Soil moisture as close to the best moisture as possible (tolerance of uniform moisture content of -3% to +1% of the optimum moisture content for the particular material being laid -Wo) If soil is too wet or too dry, the Contractor will conduct the excavation and dry up or water by water truck mounted shower nozzle respectively PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA The Contractor shall conduct spreading materials in horizontal layers of a thickness suitable to compacting equipment, taking into account the loose coefficients of the material Where embankments are to be widened the slope of the existing embankment shall be prepared by removing all surface vegetation and benched so that the new embankment is keyed into the existing embankment to the satisfaction of the Engineer The widened embankment shall then be built up in horizontal layers to the subgrade level where it shall be covered as soon as practical with subbase so that the widened area can be used by traffic as soon as possible, enabling construction to proceed on the other side of the road if required Embankment material generally shall be transferred directly from the borrow area to the prepared surface in dry weather and spread Stockpiling of embankment material shall generally not be permitted, especially during the wet season Roadway embankment materials shall be placed in horizontal layers not exceeding 20 cm, loose measurement, and shall be compacted as specified, tested for density and accepted by the Engineer, before the next layer is placed Effective spreading equipment shall be used on each lift to obtain uniform thickness prior to compacting As the compaction of each layer progresses, continuous leveling and manipulating will be required to assure uniform density Water shall be added or removed, if necessary, in order to obtain the required density In placing embankment over or against Granular Drainage Blanket or other Porous Drainage material, care shall be taken to avoid intermingling of the two materials In the case of forming vertical chimney drains, a sharply defined interface between the two materials shall be ensured by the use of temporary forms of thin steel sheeting which shall be gradually withdrawn as placing of the Fill and Porous Drainage is carried out Where embankment is to be constructed across low swampy ground that will not support the mass of trucks or other hauling equipment, the lower part of the fill may be constructed, when approved by the Engineer, by dumping successive loads in a uniformly distributed layer of a thickness not greater than necessary to support the hauling equipment while placing subsequent layers Where placing and/or compaction of material under saturated or flooded conditions cannot be avoided, the Contractor shall submit to the Engineer for approval his proposed methods to ensure adequate compaction All rock fills shall be covered with at least 200 mm of well graded material with a maximum particle size of 50 mm capable of filling all the interstices in the top of the rock fill These capping layers shall be constructed to the density requirements for embankment given in this Specification section Dumping and rolling areas shall be kept separate, and no lift shall cover any section until compaction complies with the requirements of this Specification PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA Hauling and leveling equipment shall be routed and distributed over each layer of the fill in such manner as to make use of compaction effort afforded thereby and to minimize rutting and uneven compaction 2.3 Compaction Trials Before commencing the formation of embankments, the Contractor shall submit in writing to the Engineer for approval his proposals for the compaction of each type of fill material to be used in the Works The proposals shall include the relationship between the types of compaction equipment, and the number of passes required and the method of adjusting moisture content The Contractor shall carry out full scale compaction trials on areas not less than 10 m wide and 50 m long as required by the Engineer and using his proposed procedures or such amendments there to as may be found necessary to satisfy the Engineer that all the specified requirements regarding compaction can be consistently achieved Compaction trials with the main types of fill material to be used in the Works shall be completed before work with the corresponding materials will be allowed to commence If during construction of the Works, the character and properties of the fill material change, the Contractor shall carry out further full scale compaction trials and submit the results to the Engineer for approval Throughout the periods when compaction of earthwork is in progress, the Contractor shall adhere to the compaction procedures found from compaction trials for each type of material being compacted, each type of compaction equipment employed and each degree of compaction specified 2.4 Compaction of Embankment Material Unless shown otherwise on the Drawings or otherwise specified, the Contractor shall compact the material placed in all embankment layers more than 500 mm below subgrade level until a uniform density of not less than 95 percent according to 22 TCN 333-06 II-A, is attained at a moisture content approved by the Engineer to be suitable for such density Embankment layers 500 mm or less below subgrade level and materials scarified to designated depth below subgrade in cut section, shall be compacted to a uniform density of not less than 98 percent by sand cone method according to 22 TCN 333-06 II-A at a moisture content within the range of 3% less than optimum moisture content to 1% more than optimum moisture content The optimum moisture content shall be defined as the moisture content at which the maximum dry density is obtained when the soil is compacted The Contractor shall during progress of the Work, make density tests of compacted material in accordance with 22 TCN 333-06 or AASHTO T 191 If the result of any test shows that the density is less than the required density the Contractor shall rectify the work The test shall be made to the full depth of the layer at locations as directed by the Engineer, but which shall not be more than 200 m apart For backfill around structures or in culvert trenches, at least one test per complete layer of backfill placed PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA shall be carried out In embankments, at least one test shall be performed in every 500 cubic meters of material placed The maximum dry density shall be adjusted in accordance with TCVN 4202-95 At least one group of three in-situ density tests shall be carried out for each 1000 m3 of each layer of compacted fill Tests shall be made to the full depth of the layer For backfill around structures or in culvert trenches, at least one test per complete layer of backfill placed shall be carried out Using the static steel-wheel rollers with suitable compaction load until the sand layer reaching the density K95: - Preliminary rolling: using static steel rollers 8-12T, rolling speed from to 1.5 km/ h - After 3-4 passes of rolling, conduct the filling compensation to the roadway to the specified elevation, horizontal slopes, and the cross falls - Compaction: using vibratory steel wheel rollers 25T, rolling speed from to 2.5 km/h The compaction must be conducted in accordance with compaction scheme, which has been modified through the trial compaction, compaction must be from edge of roadside to the centre line gradually, when compacting the slope, it must be conducted from bottom to top, each compacting trail must be overlapped: by the direction parallel to the centre line with the width to overlap from 25cm to 50cm, in the direction perpendicular to the centre line of the embankment, the width must be from 50cm to 100cm, and to override one third of the previous trail During the construction process, the attention is always paid to the humidity of material so that materials consistently achieved optimal moisture while compaction, if the material is too wet, it must be dried up and then conducting compaction, if material is too dry, using water trucks to water to create the moisture (notes: watering by showering nozzle to form uniform moisture) At the locations, where the machine can not enter, spreading manually and compacting by vibrating tampers on each layer, compacted thickness of each layer shall be 15cm thick The filled material is watered more water on the filled area and shall be conducted only after the uniform moisture throughout the thickness of the sprayed soil has reached Absolutely not to compact immediately after watering If the embankment occurs rubber phenomenon, then only rubber filled material must be excavated out completely and re-compacted bottom of roadbed Attention is paid to the issue of the embankment drainage, leveling to create the cross falls on both sides to ensure drainage The surface of each layer must be evenly filled, flat and the horizontal slope is always appropriate to ensure good drainage If necessary the Contractor shall use jute bags of sand and arrange of the drains at the foot of slopes to prevent erosion damage to the embankment PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA The Contractor shall take measures to ensure that the construction of the roadway embankment was finished, and the heavy vehicles are not allowed passing through to avoid the damage to embankment When construction of the embankment at the concentration of living population, the Contractor shall use the construction equipment how to mitigate harmful effect to the people (creating vibration power when using Vibrating Rollers) Upon completion of the work must have inspection records on the geometric dimensions, density, flatness and other requirements Each layer shall be compacted as specified, tested for density and accepted by the Engineer, before the next layer is placed 2.5 The attention of embankment construction Compaction Equipment Compaction equipment shall be capable of obtaining compaction requirements without detrimentally affecting the compacted material The equipment shall be a modern, efficient compacting unit approved by the Engineer The compacting units may be of any type, provided they are capable of compacting each lift of material as specified Protection of Earthworks During Construction During the construction of the roadway, the embankment shall have sufficient camber to provide drainage from the road of any rainfall and the earthworks shall be maintained in such condition that it will be well drained at all times Side ditches or gutters shall be so constructed as to avoid damage to embankments by erosion Protection of Structures If embankment can be deposited on one side only of abutments, wing walls, piers or culvert headwalls, care shall be taken that the area immediately adjacent to the structure is not compacted to the extent that it will cause overturning of, or excessive pressure against the structure When embankment is to be placed on both sides of a concrete wall or box type structure, operations shall be so conducted that the embankment is always at approximately the same elevation on both sides of the structure Rounding of Slopes Except in solid rock, the tops and bottoms of all slopes, including the slopes of drainage ditches, shall be rounded as indicated on the Drawings Adjustments in slopes shall be made to avoid injury to standing trees or marring of weathered rock, or to harmonize with existing landscape features, and the transition to such adjusted slopes shall be gradual At intersection of cuts and fills, slopes shall be adjusted and wrapped to flow into each other or into the natural ground surfaces without noticeable break Finishing Slopes All earth slopes shall be left with roughened surfaces but shall be reasonably uniform, without any noticeable break, and in reasonably close conformity with the Drawings PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA or other surfaces indicated on the Drawings, or as directed by the Engineer, with no variations therefrom readily discernible as viewed from the road Inspection and acceptance Testing frequencies Testing frequencies shall be accordance with the Specifications Dimensional Tolerances: The flatness of the compacted subgrade shall be checked every 50m both laterally and transversely at the center of the widened portions using a 3m metal straightedge The finished levels and grades for top of subgrade after compaction shall be as specified hereunder - Permitted variation from designed surface level ± 20mm - Permitted variation from designed cross section width ±50mm - Permitted surface irregularity from meter straightedge 10mm - Permitted variation from designed cross-fall ± 0.5% - Permitted variation from designed gadient ±0.2% All exposed finished fill surfaces shall be sufficiently smooth and uniform, and have sufficient slope, to ensure the free runoff of surface water Finished embankment slope surfaces shall not vary from the specified profile line by more than 100 mm PHUONG THANH TRANCONSIN 10