Lecture 1 - ExcavationObjectives:-

1. To learn the various types of excavation works.2. To relate the excavation works as per clauses in SMM23. To learn the methods of measurement as per clause D.10

– Depth classification

Outcomes:-1. Able to differentiate the different types of excavation

bases on clauses D.12.2. Able to determine the different units of measurement

based on the clauses in D10, D11 and D12.

Excavation

Excavation

Cut

RemoveBackfill

For a start we need to remove the top soil to an average depth of 200mm

100.00m

35.00m

Before you start to measure check this out:-

1. Which clause?

Answer: Clause D.7 page 17

2. Unit of measurement ?

Answer: m2 Clause D.7

3. Others?

Answer: To state average depth.

Suppose we need to do an excavation to a footing (F1) we need to know what?

Answer : Length. Width and Depth

So what is the depth?

So we have two excavation depths:

a.The first is the oversite excavation depth

which is 200mm from ground level.

b.The second is the footing excavation depth

which is 2.75m from reduced level.

How do we know the excavation depth to footing?

1st. The civil engineer will provide the information in two ways:

A. The depth from ground level or from reduced levels.

B. Based on the TBM ( Temporary Bench mark).

Ground Levels

Engineers may just give you the depth 2.95m from ground level.

In most cases Engineer will give the ground level and footing levels

How is excavation actually carried out?

A B

900mm

900mm

F1Excavate footing F1.

Size 900 x 900x 1650mm

What is the volume of Excavation?a. A

b. A + B + C

Depth of Excavation

Footing A

Footing B

We need to prevent the soil from falling due to the nature of the soil

Planking and Strutting

SOMETIMES THE SOIL IS JUST TOO WEAK ,SO WE NEED TO PROVIDE SHEET PILING TO THE SIDES OF THE FOUNDATION.

SHEET PILING

Depth classification (Clause D.10 page 17)0.25m

1.00m

2.00m 4.00m

Reasons for the depth classification

1. Different depth will result in increased difficulty in excavation.

Increased depth will pose danger to workers so temporary support could be used.

It will result in using more complicated machinery.

It enables contractors to price accordingly

Levels

Sea level:-0.00m

5.00m

The top of this hill is 5.00m above sea level.

Clause D12.2 Excavation in rock

Normal soil

Rock

Bulldozer with ripper

How to get rid of rocks?

Excavator

Jack hammer

Chemical

Dynamite

How to measure rock?

1. To measure rock separately from normal earth.

2. To measure rock as an extra over item:-

A. Total excavation ie. A+B.

B To include rock ie B as a new item as extra over.

A

B

Exercise :- Find out the excavation work to area A and B

100.00m

80.00m

25.00m

18.00m

Level:- 6.50m

Level:- 7.50mA

B

Plan view

Platform level:- 3.50m