Embankment Construction Methodology | Highway Earthwork Guide
Embankment Construction Methodology with Quality Control | MoRTH Clause 305 Embankment Construction Methodology with Quality Control – MoRTH Clause 305 Scope of Work The work shall consist of construction of embankment with approved and specified materials obtained from approved borrow areas or suitable material obtained from roadway excavation and drain excavation and in accordance with clause 305 of MORTH specifications. Reference Standards MoRTH Specifications – Section 305 (5th Revision) IRC SP: 84 IS 2720 Series – Soil Testing Approved Project Drawings Manpower & Responsibilities Manpower & Responsibilities Construction Manager Engineer / Supervisor Land Surveyor Material Engineer Safety Supervisor Helpers Construction Manager He shall be overall responsible for the activity including: Planning and organizing resources required for execution in consultation with the Project Manager. Implementation of safety requirements during the work including utility services protection. Ensuring all relevant tests are conducted as per specification. Maintaining all QA/QC records as per contract requirements. Coordinating with the consultant engineer for obtaining necessary approvals for completed activities. Engineer / Supervisor Responsibilities include: Deployment of required resources at site as per planning. Execution of work as per approved drawings. Maintaining quality control as per specifications. Implementation of safety regulations at site. Obtaining approvals for completed works from consultant/authority. Land Surveyor Responsibilities include: Establishing reference points for alignment and levels. Ensuring correct setting out of works. Checking and recording levels of completed work. Coordinating with consultant staff for final approval of finished works. Material Engineer Responsibilities include: Implementation of quality procedures as per approved plan. Ensuring all materials meet specification requirements. Conducting required laboratory and field tests as per standards. Maintaining complete material testing records and reports. Safety Supervisor Responsibilities include: Ensuring safe execution of all site activities. Implementation of project safety plan and guidelines. Monitoring compliance of safety measures at site. Setting Out After completion of site clearance, the limits of embankment shall be marked by fixing pegs on both sides at regular intervals. The chainage boards and working bench mark shall be set outside the limits of construction areas. Material Selection & Borrow Area Testing Selection of Material and Borrow Areas Material The material used in embankment shall be soil, moorum, gravel, reclaimed material from pavement, fly ash, pond ash, a mixture of these or any other material approved by the AE. It shall be free of logs, stumps, roots, rubbish and any other material likely to deteriorate or affect the stability of the embankment. The material for embankment shall be obtained from the approved source with preference to the material becoming available from nearby roadway excavation or any other excavation under the contract. The material requirements shall be in accordance with Clause 305.2 of MORTH specifications. These materials shall be free from logs, stumps, roots, rubbish or any other ingredients likely to affect the stability of the embankment. The material that has LL less than 55%, PI less than 25%, and Free Swell Index less than 50% shall be used for embankment construction. The material which is having lab MDD 15.2 minimum as per IS: 2720 Part-8 shall be used in embankment filling. The sample from the borrow area shall be brought to the laboratory and tested for the above requirements. Clods and hard humps of earth will be broken to a maximum size of 75 mm for embankment. If the moisture content (NMC) is less than OMC, the water shall be added by sprinkling considering evaporation losses, so that at the time of compaction it is in the range of 1% above to 2% below the optimum moisture content. If NMC is more than OMC, the material can be allowed to dry by exposure to the sun. EMBANKMENT/STRUCTURE BACK FILLS The following type of material shall be considered un-suitable. Material from swamps, marshes and bogs. Peat, log, stump and perishable material. Soil classified as OL, OI, OH or Pt. in accordance with IS: 1498. Material susceptible to spontaneous combustion. Material in frozen condition. Clay having LL exceeding 70 and PI exceeding 45 for Embankment. Clay having LL exceeding 50 and PI exceeding 25 for Subgrade. Material with salts resulting in leaching in the embankment. Soils having free swelling index more than 50% shall not be used as filled material. Soil having acceptedbelow free swelling index (non-expensive soils) shall be used up to 500 mm below sub-grade/embankment top. Fill material having soluble Sulfate content exceeding 1.9 gm. of Sulfate per liter (As per BS: 1377 test 10) not to be deposited with 500 mm in contact with concrete structure or cement bound materials forming part of permanent work. Fill material having total Sulfate content exceeding 0.5% by mass. (Tested as per BS: 1377 test 9) shall not be deposited with 500 mm of metallic item forming part of Permanent Work. The maximum size of coarse material in earth mixture shall not exceed 75 mm for embankment fill and 50 mm for sub grade fill. Soil material shall satisfy density requirement as given in BELOW Density Requirements for Embankment & Subgrade Material Sl. No Type of Work Maximum Laboratory dry unit weight when tested as per IS: 2720 (Part 8) 1 Embankments up to 3.0 m high not subjected to extensive flooding. Not less than 15.2 KN/cum or 1.55 gm /cc. 2 Embankment exceeding 3.0 m ht. or Embankment of any height subject to long period of inundation. Not less than 16.0 KN/cum 1.631 gm/cc. or 1.6 gm/cc 3 Sub grade and earthen shoulder / backfill Not less than 17.5 KN/cum or 1.784 gm/cc Note: Materials used shall satisfy design CBR i.e. soaked CBR shall not be less than 12% and 10% as per design locations for Heavy weight fill material. This below is not applicable for light weight fill material. Compaction Requirement The Embankment /sub grade material shall be compacted in one or more layer as per contract. The compacted field density shall meet minimum density requirement as given in BELOW Compaction Requirements for Embankment & Sub grade Sl. No Type of work/material Relative Compaction % of max. Laboratories dry density as
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