Lecture 1 - Excavation Objectives:- 1. To learn the various types of excavation works. 2. To relate the excavation works as per clauses in SMM2 3. 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.
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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