Excavation Work


About:

In this video corporate trainer, Er Chetan Sharma from Civil Guruji will tell you about the second process of a construction project that is excavation, and how to account for excavation in estimation.

Insights:

After we get the site cleaned we need to have a proper marking on the site for excavations. For this, we use a centre line layout drawing. It helps us to properly mark on the plot the position or place to excavate. Lime (0:45) is used for demarcation. It becomes easier for labourers to understand where to dig out. Excavation is what from where it begins, the foundation is laid so it is preliminary to all construction. How to find out an estimate for the excavation part, we’ll discuss. (1:04)
Footing -
On the plot we have markings and on the Centre, line layout drawing towards the bottom, we are given a table. There we have two types of footing F1 and F2 of size (1800 mm X 1800 mm) and (1500mm X 1500 mm) respectively. This is the size for footing.
Gap (2.53) -
Excavation is done from Ground Level on the soil. Where we stand is the natural ground level (NGL). Footing is in contact with the soil. Footing is of concrete and so concrete is in contact with the soil. Concrete has a fixed w/c ratio. Their quantity of water depends on the quantity of cement. Soil has the tendency to absorb moisture. If soil absorbs water from concrete its strength will be affected, get reduced so we usually give a gap of 100 mm is kept. This gap is taken from all four sides. So excavation would actually be done not just as per the footing size but taking into account this gap all around the footing. The soil will not be in contact with the concrete base. The length of excavation (5:42) along the x-direction is 1.8+0.1+0.1=2m. Similarly, the width of excavation along y-direction is also 1.8+0.1+0.1=2m.
Estimation sheet- putting up the above data on the estimation sheet we have
  1. The first item site was cleaning so excavation would be the second item with S/No 2
  2. In the drawing, we have two types of footing F1 and F 2 (6:43). In the centre line drawing top view of the plan is shown and we have F1 and F2 at different positions. On counting no. of F1 footing is 16 and no. of F2 footing is 8. So no. of items is 16 and 8 for both the footings.
  3. 2m X 2m is the size worked out considering the gap. So in place of length, we must give the input as 1.8+0.1=0.1 so that people may understand the actual size and gap. The same thing will do for width.
  4. Height (8:21) - in drawing we are given a cross-sectional distance below NGL. It is the height of the excavation i.e. 2m.
  5. Under the head total of estimation sheet, press = and left-click on no. of items *L*B*H. Excel will do the calculation for us. The unit will be cub m.
    We proceed in the same way for F2 footing
    a) Length=1.5+0.1+0.1=1.7m
    b) Width= 1.5+0.1+0.1=1.7m
    c) Height=2m
    d) No. of items=8

The total quantity of excavation (11:53) –
What we got up till is the quantity of footing we would also need a quantity of the excavation process as a whole. For the total quantity of excavation add the total values for both the footings. To do this easily on excel, use the command: “Alt+” enter” (13:02). We have two keys for Alt and + on the keyboard. This command works on a combination of 2 primary keys. So key with Alt primary and + secondary is correct.
How to merge two cells (14:55) -
select the cells to merge and go to option “merge and centre”. Cells will be merged and we would be able to give the head the total quantity of excavation. We have to select the required space, cells for the statement and simply merge. In this way, the second step will be done. In the same way, we have to find out items of each step of the construction process, we would be doing that in the following videos once this is done we will go to SOR.


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