Construction Methodology of Subgrade Construction

 Construction Methodology of Subgrade Construction

1.       Name of activity:

           Sub Grade Construction

2.       Highway Activities

3.       Description of Activity:

Construction of  Sub Grade Layers with all lifts and leads complete as per  MORT&H technical Specifications clause 305 and as per the direction of Engineer.

          Acceptance Criteria : Min.97% of MDD and as per clause 903.2.2

4.       References:

a)       Ref. to Technical Specification (MORT&H Spec. & Amendments)

a.1)    Clauses: 305,903.2.2

a.2)    Tables:   300-1, 300-2.

b)      Ref. other related works prior to this activity:

b.1)   Emb Top/OGL Approval, Borrow Area Approval, Level Recording.

c)       Ref. to Drawing(s):

c.1)    Nil

d)      IS/IRC Specifications

d.1)   Nil

5.       Scope of Work:

    This work shall consist of  construction of Embankment with the approved material from Roadway, drain excavation and  borrow pits or any other  sources approved by  Employer/Consultant/Engineer.

MANPOWER REQUIREMENT:

1.     Section In charge

2.     Site In charge

3.     Section Engineer

4.     Site Supervisor

MACHINERY REQUIREMENT:

Excavator, Dumper, Motor Grader, Water Tanker and Vibro roller.

  

Setting out will be done prior to work demarking the area of execution.

 sub-grade of 500mm (compacted thickness) shall be constructed in three layers 1st layer 200mm compacted, 2nd layer 150mm compacted and 3rd layer 150mm compacted thickness shall be done if we use static roller and if we use virbatory roller then it may  be constructed in 02 layers of 250mm each. Approved material will be placed on the previously tested approved embankment layer. Calculated quantity of sub-grade material will be placed on the entire bed. 

Sub-grade material will be spread on the entire bed with the help of motor grader. Natural moisture content will be checked. Required quantity of water will be sprinkled uniformly with water tanker on the entire surface of the bed to ensure even mixing of water throughout the bed. (Water amount will be calculated as OMC “–” NMC “+” 1% for evaporation losses.)Final grading will be done carefully as per required slope and level. Moisture content of the material will be checked and recorded in the format (If the moisture is not in the limits, the same will be brought to “–" 2% to “+” 1% range of OMC by adding or drying).Compaction will be done as per clause 305.3.6 with the help of vibratory roller. All the soft areas will be rectified before final rolling. Field dry density of the layer will be conducted and the results are recorded in the format. Successive layers shall not be placed until the layer under construction has been thoroughly compacted to the specified requirements as in Table 300-2 and got approved by the Employer/Consultant/Engineer.. Each compacted layer shall be finished parallel to the final cross-section of the Road. Clods or hard lumps of earth shall be broken to have a maximum size of 50 mm when being placed in the Sub Grade.

Safety and Environmental Activities:

         

a)     Caution Boards will be placed at the beginning and end of working site and also at risky locations.

b)    Signal man will be placed at heavy traffic locations at the time of Execution.

c)     Reflective sign boards will be placed during night near risky locations.

d)    All necessary measures shall be taken to control the disposal of all forms of waste generated by the construction operations and in all associated activities.

e)     All necessary measures and precautions shall be taken to avoid any nuisance or disturbance arising from the execution of the work.

Any other points the contractor likes to mention:

a) The manpower & machinery proposed is indicative only. The requisite qty. of resources may vary based upon site condition.

b) Any modification in execution of activity shall be done with prior information with consultant.