METHODOLOGY FOR STONE PITCHING /REVETMENT ON SLOPES

                 STONE PITCHING /REVETMENT ON SLOPES

1. Scope:

The work shall consist of covering the slopes of Guide bunds, road embankments with stone, boulders over a layer of granular material called filter.

2. Reference:

   Section 2500 of MoRTH specification & Technical specification of contract.

3. Equipments:

  Tractors, Excavators, water tanker etc…

4. Materials:

~ Pitching: The stone shall be sound, hard, durable and fairly regular in shape. Quarry stone shall be used. The stones subject to marked deterioration by water or weather shall not be accepted. The weight of stone shall be minimum 40Kg. The size of spalls shall be minimum 25mm and suitable to fill the voids in the pitching.

      Filter media: The material for filter shall consist of sand, gravel, stone, coarse sand or approved material. To prevent escape of Embank material through the voids of stone pitching as well as to allow free movement of water without creating any uplift head on pitching, one layer of filter material shall be provided underneath the pitching. The gradation of the filter media shall satisfy the requirements of clause No; 2504.2.2 of MoRTH.

5. Procedure:

5.1 stone pitching:

The banks, side slopes of Embankment shall be trimmed to the required depth as shown in Drawing.

   To maintain uniform slope and profile put up by means of line and pegs at the interval of 3 meter.

   Depressions shall be filled and thoroughly compacted.

        The approved filter granular material shall be laid over prepared base and suitably compacted to the thickness as shown in Drawing.The lowest course of pitching shall be started from the toe wall and built up in courses upwards.

~ The toe wall shall be constructed as per drawing.

~ The stone pitching shall be commence in a trench below the toe of the slope.

           Stone shall be place by hand to the required length and depth confirming to the drawing.

           Stones shall be set normal to the slope, and placed so that the largest dimension is perpendicular to the face of the slope.

          The pattern of laying shall be such that the joints are broken and voids are minimum by packing the spalls wherever is necessary and top surface is as smooth as possible.

5.2_ Procedure for Dry rubble flooring:

The work shall consist of constructing dry rubble flooring at cross drainage works.

    The base of the flooring shall be prepared to the specified levels and slopes and compacted suitably with hand rammers or other means to have an even bedding.

    The thickness of flooring shall be made with one stone only.

    The stones shall then be laid closely on prepared base in            one layer.

 5.3 Procedure for Flexible Apron:

    The flexible apron comprising loose stone boulders shall be provided beyond curtain walls.

    The weight of stone shall not be less than 40 kg.

    The dimensions of apron shall be provided as shown in the drawing.

6. Safety Precautions:

•  All dumpers, tankers shall be provided with reverse horn & light.
•  Wherever required, Flagman shall be provided.
•     The speed of vehicles plying in stretch shall be restricted to 30kmph.
• Leveling staff shall be fiber or Wooden.
• Any labour, if being used in the job for surveying shall be screened and trained.
•  All workmen at work area shall wear PPE^·s and reflective jacket.
• The pitching work shall not disturb the live Traffic.