Some useful tips for footing excavation measurements

In this informative construction video tutorial, you will learn how to make calculation for earthwork excavation on the basis of elementary thumb rules. Besides, you will also learn how to make cross examination at the time of estimation.

This video is very useful for building engineer or civil site engineer.

Normally, earthwork is necessary for all the civil engineering projects roads, railways, earth dams, canal bunds, buildings etc.

This earthwork may range from either excavation or earth filling or sometimes both will reach out to as per the required shape and level.

Fundamentally, the volume of earthwork is measured from length, breadth and depth of excavation or filling.

The following items are included in earthwork :- Excavation, Backfilling, Disposal of surplus earth

Here, the calculation is done on the basis of IS Code 1200 for BOQ.

The calculation of earthwork billing is done in the following ways :-

1) Mode of measurement of billing – Types of measurement used for billing of excavation. It is done with the formula like Length x Breadth x Height/Depth

2) Different types of billing – a) R.A. Bill (Running Account Bill)
b) Find Bill

To get more details about the calculation of earthwork excavation, go through the following video tutorial.

Video Source: CE&T-Civil Engg & Technology

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Published By
Rajib Dey
www.constructioncost.co
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How impact of trench excavation on adjoining building is measured with rule of thumb

The adjoining buildings are greatly impacted with trench excavation and lead to settlement. This construction article briefly explains how to gauge the impact of trench excavation on adjoining buildings with rule of thumb.

The two factors are mainly responsible for impact of trench excavation on the buildings:

• Soil relaxation because of excavation
• Diminishing of groundwater owning to excavation

Soil relaxation because of excavation

When a trench is excavated adjoining a building, soil relaxation and subsequent settlement of the building is increased.

So, there should be sufficient support for the trench to resist soil relaxation. On the other hand, excavate the trench far from the foundation but it will not be a legitimate option always.

Besides, a rule of thumb is applied to examine whether the trench excavation affects the nearby building or not. Draw a line with 2H:1V from the bottom of the foundation. If the trench remains within this line, then engineer shall look forward to soil relaxation and eventual settlement of building foundation.

Lastly, if the soil at job site comprises of loose sandy soil, then draw the line with 3H:1V instead of 2H:1V.

Diminishing of Groundwater due to excavation: Generally, groundwater proceeds and seeps into the excavation from the adjacent areas of the trench. It will reduce the level of ground water in the trench vicinity area. Effective stresses are raised due to groundwater lowering and accordingly the foundation experiences settlement.

Last but not least, diminishing ground water raises effective stress in clay layer and higher effective stress leads to foundation settlement.

Read more

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Published By
Rajib Dey
www.constructioncost.co
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