This article describes how to calculate earthwork excavation for foundations in all types of soils, including murram, hard murram, soft rock (without blasting), hard rock (without blasting), and rock (with blasting).

List of IS Code for earthwork excavation

The Bureau of Asia Standards Code listed below will apply. In all cases, the most recent revision of the codes must be used for earthwork.

• IS - 4081 is the safety code for blasting and related drilling operations.

• IS - 1200 Building Work Measurement Method

• IS - 3764 is the excavation work safety code.

• IS - 3385 IS - 2720 Part II Code of Practice for Measuring Civil Engineering Works Moisture content determination

• Light compaction is used to determine the moisture content-dry density relationship.

• The sand replacement method determines the dry density of soils in place.

• The core cutter method is used to determine the dry density of soils in place.

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Drawings for earth work excavation for the foundation

Drawings for earthwork excavation for foundations should include all necessary drawings showing the areas to be excavated, filled, priority sequence, and so on. The Engineer on the job site must strictly adhere to such drawings.

What are the processes of excavation in the Construction Industry?

1. Before beginning excavation, the client/contractor/builder must obtain valid soil royalty from the relevant government department.

2. Before excavation, the client/contractor/builder must survey the site and establish proper lines and levels for various works such as earthwork in excavation for leveling, basement, foundations, plinth filling, roads, drains, cable trenches, pipelines, and so on. This survey shall be conducted by taking accurate cross-sections of the area perpendicular to establish reference/grid lines at 5 m intervals or closer as determined by the site Engineer based on the ground profile. These must be checked by the Engineer and properly recorded.

3. Fences, trees, plants, logs, slumps, bushes, vegetation, rubbish slush, etc., and other objectionable matter must be removed from the excavated/filled area. If any tree roots or stumps are discovered during excavation, they must also be removed. The removed material must be burned or disposed of. Before filling with earth, the area must be cleared of all loose/soft patches and topsoil containing deleterious matter/materials.

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Different ways of earthwork excavation for the foundation

Earth Work in Excavation Manually for depth up to 1.5m from Existing GL:

a) Classification: Any earthwork will be classified under the following categories.

i) All kinds of soils: These shall include all kinds containing kankar, sand, silt, murum and/or shingle, gravel, clay, loam peat, ash, shale, etc., which can generally be excavated by spade, pick-ax, shovel, and JCB which is not classified under a soft and decomposed rock, and hard rock defined below. This shall also include embedded rock boulders not bigger than 1metre in any dimension and not more than 200 mm in any of the other two dimensions.

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ii) Soft rock includes rock, boulders, slag, chalk, slate, hard mica schist, laterite, and other materials that must be excavated with or without blasting and can be excavated with a JCB, porcelain with a bucket, ripper, chisel, picks, hammer, crowbars, wedges, and other materials. Excavation on the macadam and tarred roads and pavements is also required. This includes rock boulders no larger than 1 meter in any dimension and no larger than 500 mm in any other two dimensions. This item will also include measurements for dismantled masonry.

iii) Hard rock is defined as rock that cannot be easily excavated with pick-axes, hammers, crowbars, JCBs, and wedges and must be heated where blasting is prohibited or blasted. For measurement, they must be stacked separately.

Important Points

This includes any rock, cement concrete, or RCC whose excavation cannot be done with mechanical/hydraulic excavators and where blasting has been used.

The decision of the site in charge as to whether or not a particular rock requires blasting shall be final and binding. Before stacking, any secondary blasting or breaking of blasted boulders must be done on-site.

After blasting, blasted rock that can be lifted by hand, along with spalls, should be stacked at the site.

b) The earthwork in the excavation shall be completed in accordance with the drawings of the architect and structural consultant, up to the required depths, levels, and alignments in all types of soils. The depth of the foundation will be determined by the Engineer. The Site Engineer should do the lining work.

Any roots or trees encountered during the excavation must be cut and smeared with coal tar. Excavated earth must be stacked at least 3 meters away from the trenches to avoid damaging the sides of the excavated trenches. The excavated trenches' sides must be vertical and straight, and the bottom must be uniformly leveled, watered, consolidated, and ready for termite treatment.

c) If the excavation is deeper than 2 m in firm soil, the sides of the trenches must be increased by 50 cm on either side to maintain a slope of 0.25 to 1. In loose, soft, or slushy soil, the width of the step should be increased, the sides sloped, or shoring and strutting performed.

d)Excavation for drain work should have the required slope, shape, and gradient on the sides and bottoms. The cuts must be made from top to bottom. Undermining or undercutting is not permitted under any circumstances. The finished surface must be neatly leveled and compacted. The earth from the cutting shall be used directly for filling the plinth or the grounds.

e) While the foundation work is being done, the foundation trenches must be free of water and muck.

Safety measures during excavation work of the foundation

1. The Engineer must take adequate precautions to ensure that the excavation for the building foundation does not jeopardize the stability and safety of the adjacent structure.

2. To avoid negligence during construction operations, engineers should take precautions for the safety of people, property, or neighbor's property.

3. Excavated materials must be used as backfill to the extent possible. Clods, salts, sulfates, organics, and other foreign materials must be avoided as infill material. All large earth particles must be broken or removed. Where the excavated material is mostly rock, the boulders must be broken into pieces no larger than 150 mm and mixed with properly graded fine murum material.

4. Once the foundation work has been accepted and measured, the spaces around the foundations, structures, pits, trenches, and so on must be cleared of all debris and filled with earth in 15 cm to 20 cm layers, with each layer being watered, rammed, and properly consolidated before the next one is laid. Every layer must be properly consolidated.

How to calculate earthwork excavation for the foundation

In general, the measurement mode for earthwork in excavation includes backfilling: To estimate earthwork excavation for a foundation. We must determine the volume of the foundation.

For Example- Length of Foundation = 4 meter

Depth of the Foundation = 2 Meter

Then Value of earthwork excavation for the foundation= is 4x3x2=24 Cubic Meter.

These measure earthwork in excavation, foundation, basement, raft, pits, trenches, underground, septic tank, soak wall, and other applications.

Note:- This includes the cost of earthwork for the excavation Lead for deposition/disposal of excavated material, as specified in the other work item. This should be paid in addition.