Embankment|Earthwork embankment|Embankments and Backfill Construction

Embankment and backfill construction includes the construction of all embankments for canals, drains, roads, river, structures and filling in other parts of works with suitable materials obtained from canals, drains, rivers and structure excavation or extracted from borrow areas.

All embankments and backfill construction are constructed to the lines and levels shown on the drawings or as directed by the Engineer. The materials for embankment should not contain any stump, brush, weed, root, clod, and matter that may decay. There should be approved by the specification specialist for the details of his proposed method of obtaining such materials from borrow pits within the borrow area.

Fig1. Road construction on a Embankment pit in the water

Borrow Areas for Backfill construction

The materials used for embankment is obtained from the sources as described in the Bill of Quantities. The Contractor arranges the borrow area showing its location on the drawings and request in writing its approval from the Engineering Department.

Upon approval thereafter, the Contractor pay to the owners of such borrow area, the cost of procurement of the materials from such privately owned areas as directed by the Engineer Engineer, except the cost of furnishing the materials such as excavation of the materials, which should be included in the rates in the Bill of Quantities.

Borrow pits is located in places approved by the Engineer, but is not be within a minimum of two (2) meters from the toe of a completed embankment, spur, guide bank or other works, and are not located on the proposed canal route or other works.

The borrow pits are cleared and grubbed as provided in norms so that the excavated materials in the borrow pits are not contained any stumps, brush, roots, weeds, turf and any matter that goes to decay.

As far as practicable the moisture content of materials is conditioned in the borrow pit before excavation, by irrigation into the borrow pit when moisture introduced or by excavation of drainage or trenches for reducing excessive moisture.

Ductility Test of Bitumen and its Suitability for Road Construction

Upon completion of the construction of all embankments, the Contractor should restore all borrow areas in such a manner that the ground elevation of the restored borrow areas is as same as the neighboring areas, so as not allow rainwater to stagnate on borrow areas to the satisfaction of the owner of the borrow area and the Engineer, or as otherwise directed by the Engineer.

Fig2. cutting and filling for the construction of structure

Except as provided otherwise, no direct payment made for preparatory operation and maintenance of borrow pits including clearing, stripping, excavation operations necessary to properly condition the material and any other works to furnish the embankment materials in the borrow areas. These costs included in the appropriate unit rates for the embankment of which materials are obtained from the borrow areas from distances as specified in the Bill of Quantities.

The embankments for branch and distributary canals are constructed to the lines and grades shown on the drawings or established by the engineer.

Embankments

General

The embankments construction is constructed to the lines and grades shown on the drawings or established by the Engineer.

Embankment Construction

Before the materials for the first layer of the embankment is placed, the foundation for the embankment is prepared as provided for in below section and is moistened or dried and compacted in the manner hereinafter specified for a compacted embankment to be placed hereon.

Fig 3. Embankment protecting the River Bank

The materials are deposited in horizontal layers and the thickness of each horizontal layer after compaction is not more than twenty (20) centimeters in any case. Embankments are not widened with loose material dumped from the top. All lumps and clouds of heavy clay shall be thoroughly broken down by means of proper instruments and moisture control for materials is thoroughly made so as to secure high enough unit weight of embankment. Compaction is not permitted until the moisture content of the soil has been adjusted unless otherwise approved to within + 3% and – 3% from the optimum moisture content.

When the materials have been satisfactorily conditioned, it is compacted by pneumatic tired rollers, sheep foot rollers, tamping rollers, vibration rollers, vibration roller with pad foot, or mechanical tempers upon the Employer’s Representative’s approval. Where mechanical tampers are used to compact soils in confined areas, they are equipped with suitably shaped heads to obtain the required density.

Where placing and spreading operations are carried out by hand methods, which deposits materials directly from excavation by human power with the Engineer’s approval, the materials are thoroughly compacted by mechanical tamper or other approved means after spreading the materials horizontally. The distribution of materials will be homogeneous and free from lenses, pockets, streaks or other discontinuities.

In normal circumstances, the dry density of the soil in the compacted material is not less than ninety (90) percent of the maximum dry density as determined by Standard Proctor Compaction Test for the material being compacted with a probability of the maximum ten (10) percent failure except as otherwise directed Engineer Department. In no case, however, the degree of compaction be less than 80 percent. The minimum number of samples for testing is as specified in testing method thereof.

Embankment slopes after trimming work are compacted by mechanical tamper or approved means. The trimmed materials are spread on the outer slopes of the embankment unless otherwise specified or directed by the Engineer. Compaction to a specified density for the spoil bank is not called for this disposed of material, but materials to be disposed of are evenly spread over the slope to the satisfaction of the Engineering Department.

Measurement and Payment:

Measurement for payment of embankments is made of the materials in place to the prescribed lines, grades, and dimensions shown on the drawing or as directed by the Engineer. The extra filling to the embankment is not measured for payment.

In the event that the compaction of any stretch of the embankment is less than the required degree in normal circumstances but more than the minimum mentioned above, payment for the stretch of the embankment made after deducting an amount as demonstrated below:

M = Required Degree of Compaction in normal circumstances

N = Actual Degree of Compaction Achieved

R = Unit rate of Filling in Embankments which is taken as the higher of the unit rates quoted by the Contractor in the Bill of Quantity or the unit rate of the project in its rate analysis accompanying the Cost Estimate.

Unit Rate of Deduction to be Applied (D) = (1 – N/M) x R

Amount of Deduction = D x Measured Quantity

Embankment for Command Area Development Works

The embankment for Command Area Development works is classified into embankment Type A and B depending upon the source of materials and the haul distance as specified in specification hereof and in the Bill of Quantities. The embankment for Command Area Development works constructed to the lines and grades shown on the Drawings or established by the Engineering Department.

Embankment Construction

Before the materials for the first layer of the embankment is placed, the foundation for embankment is prepared as provided and is moistened or dried and compacted in the manner hereinafter specified for compacted embankment to be placed hereon.

Fig4. embankment,borrow meaning, road construction in water

The materials deposited in horizontal layers and the thickness of each horizontal layer after compaction is not be more than twenty (20) centimetres in any case. Embankments should not widened with loose material dumped from the top. All lumps and clods of heavy clay is thoroughly broken down by means of proper instruments and moisture control for materials is thoroughly made so as to secure high enough unit weight of embankment.

Compaction is not permitted until the moisture content of the soil has been adjusted unless otherwise approved to within + 3% and – 3% from the optimum moisture content.

When the materials have been satisfactorily conditioned, they are compacted by tamping rollers, vibration roller, vibration roller with pad foot, mechanical tampers or hand tampers upon the Engineer’s approval.

Where mechanical tampers are used to compact soils in confined areas, they are equipped with suitably shaped heads to obtain the required density. Where hand tampers are used, the tamper shall be of iron or concrete of weight not less than 15 kg with a gravity fall of a minimum of 30 centimeters.

Where placing and spreading operations is carried out by hand methods, which deposits materials directly from excavation by human power with the Engineering Department’s approval, the materials are thoroughly compacted by mechanical tamper, hand tamper or other approved means after spreading the material horizontally. The distribution of materials is homogeneous and free from lenses, pockets, streaks or other discontinuities.

In normal circumstances, the dry density of the soil in the compacted material is less than eighty-eight (88) percent of the maximum dry density as determined by Standard Proctor Compaction Test for materials beings compacted with a probability of the maximum ten (10) percent failure except as otherwise directed by the Engineer. In no case, the degree of compaction is less than 80 percent.

Embankment slopes after trimming work are compacted by mechanical tamper, hand tamper or approved means. The trimmed materials are disposed of on the outer slopes of the embankment unless otherwise specified or directed by the Engineering Department.

Compaction to a specified density for the spoil bank is not called for this disposed of material, but materials to be disposed of are evenly spread over the slope to the satisfaction of the Client.

M = Required Degree of Compaction in normal circumstances

N = Actual Degree of Compaction Achieved

R = Unit rate of filling in Embankment which is taken higher of the unit rates quoted by the Contractor in the Bill of Quantity or the unit rate of the project in its rate analysis accompanying the Cost Estimate.

Unit Rate of Deduction to be Applied (D) = (1 –N/M) x R

Amount of Deduction = D x Measured Quantity

Measurement and Payment for Backfill construction

Measurement for payment of embankment for Command Area Development Works is made of the material in place to the prescribed lines, grades and dimensions shown on the drawing or as directed by the Engineering Department. The extra filling to the embankment is not be measured for payment. Payment for embankments is made at the unit rate per cubic meter of the measured quantity, which unit rate include all cost of excavation, transportation of the excavated materials from the excavation sites or from the temporary stockpile including re-handling, if required, to place of final use, and the costs of placing materials in layers, furnishing water, moistening or drying the materials and compacting the materials as provided in this Section and trimming and compacting the slopes, including all cost of labour, materials and construction equipment.

Embankments for Service Roads

The embankments for service roads constructed to the lines and grades shown on the drawings or established by the engineer.

Embankment and Backfill Construction

Before the materials for the first layer of the embankment is placed, the foundation for embankment is prepared and shall be moistened or dried and compacted in the manner hereinafter specified for the compacted embankment to be placed thereon.

The materials are deposited in horizontal layers and the thickness of each horizontal layer after compaction is more than twenty (20) centimeters in any case. Embankments are not widened with loose material dumped from the top. All lumps and clouds of heavy clay are thoroughly broken down by means of proper instruments and moisture control for materials are thoroughly made so as to secure high enough unit weight of embankment. Compaction should not be permitted until the moisture content of the soil has been adjusted unless otherwise approved to within + 3% and – 3% from the optimum moisture content.

When the materials have been satisfactorily conditioned, they could be compacted by pneumatic tired rollers, sheep foot rollers, tamping rollers vibration rollers, vibration roller with pad foot, or mechanical tampers upon the Engineering Department approval. Where mechanical tampers are used to compact soils in confined areas, they are equipped with suitably shaped heads to obtain the required density.

Where placing and spreading operations are carried out by hand methods, which deposits materials directly from excavation by human power with the Engineer’s approval, the materials are thoroughly compacted by mechanical tamper or other approved means after spreading the material horizontally. The distribution of materials should homogeneous and free from lenses, pockets, streaks or other discontinuities.

The dry density of the soil in the compacted material is not less than ninety-five (95) percent of the maximum dry density as determined by Standard Proctor Compaction Test for the material being compacted with a probability of the maximum ten (10) percent failure except as otherwise directed by the Engineer.

Embankment slopes after trimming work are compacted by mechanical tamper or approved means. The trimmed materials are disposed of on the outer slopes of the embankment unless otherwise specified or directed by the Engineer. Compaction to a specified density for the spoil bank is not called for this disposed of material, but materials to be disposed of are evenly spread over the slope to the satisfaction of the Employer’s Representative.

Measurement and Payment

Measurement for payment of embankments for service roads is made of the materials in place to the prescribed lines, grades and dimensions shown on the drawing or as directed by the Engineer. The extra filling to the embankment is not measured for payment.

Payment for embankments is made at the unit rate per cubic meter of the measured quantity, which unit rate include all cost of excavation, transportation of the excavated materials from the excavation sites or from the temporary stockpile including re-handling, if required, to place of final use, and the costs of placing materials in layers, furnishing water, moistening or drying the materials and compacting the materials as provided in this section and trimming and compacting the slopes, including all costs of labour, materials and construction equipment.

Embankment/Backfill Around Structures

Backfill/Embankments around structures are placed to the lines shown on the Drawings, as prescribed in this paragraph, or as directed by the Engineer. The type of material used for backfill, the amount thereof, and the manner of depositing the material are subject to approval. So far as practicable, backfill material is obtained from material already moved. If the material is not available from this source or from adjacent excavations, additional material shall be obtained from approved sources.

Fig6. Around the structure the embankment and cutting are done

Backfill around or on sides of the following structures or portions of structures, is compacted to slopes shown on the drawings from the top of the concrete walls, provided that where the structure is located in the compacted embankment, the backfill is compacted to the elevation prescribed for the adjacent compacted embankment.

Regulators and check structures
Escape channel and bridge over it.
Open transitions at the ends of all structures.
Cut and cover conduits
Cross drainage works

To avoid interference with the construction of abutments, walls or return walls, the Contractor, at points to be determined by the Engineer, suspend work on embankments forming approaches to such structures, until such time as the construction of the latter is sufficiently advanced to permit the completion of approaches without the risk of interference or damage to the works.

Unless directed otherwise, the filling around structures is carried out independent of the work on the main embankment. The fill material is not placed against any abutment or wing wall unless permission has been given by the Employer’s Representative, but in any case not until the concrete or masonry has been in position for 14 days. The embankment is brought up simultaneously in equal layers on each side of the structure to avoid displacement and unequal pressure. The sequence of work in this regard is approved by the Employer’s Representative.

All material used for backfilling should not an organic soil or highly plastic clay having plasticity index and liquid limit more than 20 and 40 respectively when tested according to IS: 2720. The fill material is deposited in horizontal layers not exceeding 20 centimeters in loose thickness and compacted thoroughly.

Where the provision of any filter medium is specified behind the abutment, the same is laid in layers simultaneously with the laying of fill material.

Where it may be impracticable to use power rollers or other heavy equipment, the compaction is carried out by mechanical tampers or other methods approved by the Engineer. Care should be taken to see that the compaction plant does not hit or come too close to any structural member so as to cause any damage to them or excessive pressure against the structure.

In placing and compacting backfill or embankments adjoining concrete pipes or small structures, sufficient material is carefully placed and compacted in layers equally along the sides of the pipes or structures in order to firmly establish line and grade before placing and compacting the adjoining embankment. The Contractor should responsible for any damage to structures caused by his operation in placing or compacting embankments or backfill material adjoining to structures, and shall repair damage to the full satisfaction of the Engineer. Construction traffic is not using the prepared surface of the embankment without the prior permission of the Engineer. Any damage arising out of such use is, however, be made good by the Contractor at his own expense.

Measurements and Payment

Earth embankment and backfill construction are measured by taking cross sections at intervals in the original position before the work starts and after its completion and computing the volumes of earthwork in cubic meters by the method of average end areas.

Filter gravel behind abutments is measured and paid for as separate item of work, in position in cubic meters.

The Contract unit rates for the items of embankment and backfill construction are include the following:

Setting out;
Compacting original ground;
Scarifying or cutting continuous horizontal benches 0.3 m wide on side slopes of existing embankment or slopes as applicable;
Compaction to specification requirements;
Shaping and dressing top and slopes of the embankment and backfill including rounding off corners;
Working on narrow widths off embankment;
Restricted working of the embankment;
Restricted working at sites of structures;
Excavation in all soils from designated borrow areas and transporting the materials to embankment site within all lifts and loads not exceeding 50 m unless otherwise provided for in the Contract, and
All labor, materials tools, equipment and incidentals necessary to complete the work to the Specification.

Penetration Test of Bitumen – Procedure, Apparatus and Uses for Road Construction

Field Embankment Test

The field embankment tests are made in such a manner as to obtain the optimal passage number of compaction equipment in relation to the thickness of layer after spread to attain the highest dry density of the embankment after compaction, and to obtain the allowable moisture content range of the materials.

No separate payment is made for the field embankment tests. All costs of furnishing materials, labor, construction equipment and executing the field embankment test included in the unit rates for applicable embankment and backfill construction items in the Bill of Quantities.

The Contractor carry out the control tests on fill materials as required in the Specification as and when required by the Employer’s Representative. Tests required are:

Specific Gravity Test
Moisture Content Test
Grain Size Analysis
Liquid limit
Plastic Limit
Compaction Test
Field Density Test

As an approximate average, a compaction, specific gravity test, grain size analysis, and plastic index will be required per 4,000 cubic meters of filling materials.

The Contractor provide the necessary equipment, labour and transport equipment for carrying out the sampling and testing in the Project Laboratory. The soil samples is stored and tested at the Project Laboratory under the supervision of the Engineer.