Construction Methodology of Rockfill Embankment

SCOPE

The work covers embankment constructed with pieces of rock and shall be in accordance with the lines, graded, and cross-section as shown in drawings or as directed by the Engineer. There shall be a minimum of 500mm thick earthen cushion of suitable materials excluding subgrade over the rockfill embankment.

MACHINERY

1. Excavator 
2. Dumper
3. Dozer
4. Motor Grader
5. Vibratory roller
6. Water tanker with sprinkler
7. Survey kit
   1. Auto level
   2. Measuring tape etc.

MANPOWER

1. Sr. Engineer
2. Jr. Engineer
3. Supervisors
4. Labour

MATERIAL

Rock Pieces

The rockfill shall consist of hard, durable, and inert material preferably maximum size not exceeding 300m and per cent finer than 125mm not exceeding 10%.

METHODOLOGY

Setting out

After the site has been cleared as per clause 201, and Clearing and Grubbing, the work will be set out true to lines, grades, slopes, curves, and sections.

Transporting of Material

The approved material shall be transported by means of dumpers and dumped in the form of heaps as per 305.2.2.2 of MORT&H specification.

PROCEDURE

1. The toe line and centerline are marked, and pegs will be driven.
2. The material shall be tipped, spread, and levelled in layers extending to the full width of the embankment by a suitable dozer.
3. Fragments of rock shall then be spread on the top of the layer to the required extent and layer compacted by a minimum of 5 passes of a vibratory roller having static weight 8-10 tonnes.
4. The gradation of the rock material shall be 300mm to 125mm and below 125mm should not exceed 10%. In other areas where there is a possibility of seepage of water, the maximum size of the rock material is 300mm to 125mm.
5. To protect the water seepage from overland flow, the edges, last 2 to 3m wide strips will be constructed with ordinary soils.
6. The compacted thickness of each layer shall not exceed 500mm.
7. After compaction of each layer, the surface voids shall be filled with broken fragments.
8. The top layer of rockfill, on which normal earth fill will rest, shall be thoroughly blinded with suitable granular material to seal its surface.
9. It shall be executed after prior approval.

Traffic Safety

Traffic safety shall be taken care of as per the safety plan where earthwork activities are in progress.  All the vehicles will have red flags and reflective bands on the rear. Flagmen will be deployed where the crossing of the existing road is unsafe.

Surface Finish and Quality control of work

The top layer of rockfill, on which normal earth fill/ Crusher dust will rest, shall be thoroughly blinded with suitable granular material to seal its surface.

Also Read: Introduction to Earned Value Management