Filling work in trenches shall be carried out in layers of thickness not exceeding

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JKSSB JE (Civil) Official Paper (Held On: 19 Nov, 2023)

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Answer 1

Explanation:

As per standard engineering practices and IS 1200 guidelines (Methods of Measurement of Building and Civil Engineering Works), filling in trenches must be done in layers not exceeding 200 mm thickness.
Each layer should be compacted properly before placing the next to ensure uniform strength and avoid settlement.
This applies to backfilling with soil, sand, or granular material.

Additional Information

Backfilling is done to restore the excavated area after laying pipes, cables, or foundations in trenches.
It ensures stability, prevents settlement, and supports the installed structure.
As per IS 1200 and CPWD specifications, the material should be filled in layers not exceeding 200 mm, each layer being properly compacted before the next is placed.
Backfill may consist of excavated soil, selected granular soil, sand, or engineered fill, depending on the type of utility in the trench and required compaction.
Each layer must achieve the required dry density, often checked using Proctor Test results.
Poor compaction may lead to uneven settlement, pavement cracking, or failure of underground utilities.