Lecture 3 - Excavation

Objectives:-

1. To learn the excavation work, backfill and

removal of surplus soil.

2. To relate the excavation works as per

clauses in SMM2

3. To determine the various clauses applied

to the excavation works.

Outcomes:-

1. Able to differentiate the different clauses

used

2. Able to write down the dimensions clearly.

A single storey house with pad

footings.

Foundation (Footing)

Ground level

Resistance from the soil.

Loading from the house

So to construct a house what do

we need?

1. A foundation, in this case this a a pad

footing.

2. So we need to determine first the type

of foundation designed by the engineer.

3. Each type of foundation may not involve

the same type of excavation activities.

4. Each activity may use different types of

machineries or method of excavation.

Clause D.12.6. Excavation pit

for footing

Section of footing Plan of footing

Footing

Stump

Excavation depth

Plan dimension

a

b

A three-storey building with pile

foundation Clause D.12.8 page 18

Ground level

Pile cap

R.C. pile

Stump

Hard strata

Excavating for pile caps and

trenches for ground beams

Ground beams

Stump

Pile capR.C. pile

Summary of excavation work:-

1. To measure excavation work we must

first determine the type of excavation

work.

2. With the type of excavation determined

find out which clause to be used.

3. Using the clause now you could

determine next the dimensions of

excavation.

Disposal of excavated material

Clause D17 to D22 page 19 & 20

On siteOff site

Boundary of construction site

Filling Clause D.23 to D.34 page 20

& 21

Filling material

Column stump

RC footing

Classification of filling material

Clause D.23

1. Materials arising

from the excavation

The material that is

suitable for filling.

2. Materials that is to be treated

or selected 1. Material to be

filtered and to be

separated from those

unsuitable material

like rubbish, timber

and stones.

2. It involves more

time, labour and of

course more

expensive.

Sieve

Treated material

3. Material obtained off-site

1. Material from the

excavated site is not

suitable.

2. Material for backfill

to be purchased from

other sources, like

imported earth,

Exercise no. 1- Measure the excavation

work to the footings (F1)

Plan of a brick wall ( 3 nos.)

How to write down the answer?

First find out the type of foundation from

the drawing.

Then search for the relevant clause in

SMM2.

Then find out the unit of measurement.

Also find out any other conditions

necessary.

How to write down the answer?To do that we need to know what type of work involved.

So we need more information about this structure

The structure

THE ELEVATION

With these two additional diagrams we can now

understand the structure and know the construction

method.

So how many items we need to

measure?

Find out the excavation depth first.

Description

1. What type of activity?

Excavate pit for brick wall foundation.

2. From what level?

From ground level.

3. To what depth?

Need to find out, and classify according to clause D.10

4. Anything else?

Check clauseD.12.6 again.

Description

Lets put it all together:-

Excavate pit for brick wall

foundation commencing from

ground levels with depth not

exceeding 2.00m. ( 3 nos.)

Write this in your taking off paper

Excavate pit for brick

wall foundation

commencing from

ground levels with

depth not exceeding

2.00m. ( 3 nos.)

First write down the description

How to write down the answer?

Depth of excavation: 1125

50

1175

Length of foundation:

Width of foundation:

Then you need to provide side cast or

workings

Description

Your answer

Side cast/working

Excavate pit for brick

wall foundation

commencing from

ground levels with

depth not exceeding

2.00m. ( 1 no.)

L

W

D

m3

3/

Measure the excavation work again

based on the following:-

1. Another brick wall with foundation F2 (5

nos.) with the same layout but the depth

(d) is now 3.05m.

2. Write down your answer similar to the

earlier exercise in the same piece of

paper.

Exercise no. 2- measure the F1

again based on this information.

Is that all?

No, you still need to remove the soil you have excavated.

So you need to write description again for the removal of surplus soil.

1st. Remove what?

Answer: Surplus soil.

2nd. To where?

Answer: Away from site or off site(clause D.19)

3rd. Unit?

M3 Clause D.19

Your answer

Removing surplus

excavated soil off site

including disposal to

contractor’s own tip.

Answer similar to excavation work for

foundation