Excavation refers to the groundwork step or action of the construction project. It commences from the pits for the building’s bases and foundations and prolong up to the giving over of the construction project.
Materials and tools utilized
The following are some of the materials which are utilized in the earthwork for foundation.
- Line and pins
- Iron Pan
- Sledge Hammer
- Boning Rod
- Spade Wedge
- Crow Bar
- Pick Axe
- Layout Plan
- Centerline Drawing
Size of Foundation
- For main walls – 4’0” depth
- For Partition walls – 2’0” depth
Scope of Work
- Constructing protection bunds and drains
- Marking Boundaries of building
- Making up to cut off level
- Research for ground levels
- Survey for top levels
- Setting out of corner benchmarks
- Excavation up-to permitted depth
- Construction of interrelated trenches and dewatering wells
- Construction of protection bunds and drains
Procedure of Working
The scope of soil and rock strata is assessed by creation of trial pits in the site of construction. The depth and excavation is resolute in accordance with following instructions in the site:
- In case of isolated footing the length has to be one and half times of the width of the foundation base
- In case of adjacent footings with clear spacing smaller than two times the width that is one and half times its length
- For black cotton soils 1.5m in general and 3.5 m
Ground tracing or the setting out refers to the procedure of spreading down the center lines and excavation lines on the ground surface before the commencement of excavation. The focal line of longest outer wall of the building is marked on the ground surface by extending a cord between mild or either steel pegs. All of the peg may be projected approximately 25 to 50 mm form the ground surface and 2m from the rim of the excavation. The mark is put in the border with help of lime powder. The center lines of other walls are marked vertical to the longer walls. A right angle can be created by creating 3, 4 and 5 triangles. Likewise, outer lines of the foundation base channel of each cross walls and are also set out.
Removal of Excess soil
Make tentative estimations about the excavated materials to be recycled and reutilized in different activities such as filling, gardening, and construction of roads. As much as possible, try to conduct excavation and filling at the same time to keep away from double handling. Choose and stack the necessary materials in a neat and distant place so that it will not hinder other building activities. The surplus or unnecessary materials have to be straight away be taken away and safely disposed by applying any of the following techniques.
- Use of departmental labour.
- Use of tractor.
- Use of trucks.
Quality checks for excavation
- Keeping the records of the ground level and assess size of base
- Immediate disposal of inappropriate materials for filling.
- Neatly stacking necessary material for backfilling to steer clear of double handling.
- Strata classification permission by experienced authority.
- Dressing bottom and sides of pits in accordance to sketches with reverence to centerline.
- Essential safety procedures observed.
Quality checks for filling
- Keeping record of the initial ground level
- The specimen is accepted for back filling.
- Essential marking/ reference points are recognized for final level of backfilling.
- Back filling is being undertaken in layers (15cm to 20cm).
- Necessary watering, compaction is done.
- Necessary density is achieved.