SOIL EXCAVATION IN BUILDING CONSTRUCTION
WHAT IS EXCAVATION IN BUILDING CONSTRUCTION
Excavation is the movement of earth, rock or other materials with tools, equipment or explosives. It is one of the preliminary activities of the construction works. It also includes trenching, wall shafts and underground, etc.
The procedure for excavation of soil at any construction site involves the understanding of building line, structural drawings, setting out of plan on ground, excavation of soil and removal of soil excesses.
TYPES OF SOIL EXCAVATION
1. Soil Strip Excavation (Removal of topsoil)
This is the process of stripping the surface of the ground or the top soil. The first section of of the ground to be excavated is the top soil or vegetable soil. It is generally soft and very easily compressed and if the foundation of the building are built directly on it, the building will tends to sink into the ground by compressing the vegetable topsoil. The average thickness of the vegetable topsoil is usually 150mm. The layer is excavated separately from the other excavation wall.
2. Reduced Level Excavation
On a sloppy site, it is necessary to cut into the banking on one’s side of the proposed building while filling the suitable material (possibly the material ‘cut’ out) on the other side, in oder to achieve the level working surface or formation level. This method of excavating in one area and using the same material for filling purpose is known as “Cut and Fill” and it is frequently used in the construction of roads.
3. Bulk Excavation
This occur where large bulling of subsoil required to be excavated is order to reach the formation level. This type of excavation may be reduced level to provide for the basement area.
4. Trench Excavation
This is the excavation of the trenches from the formation level to a lower level. In this trenches, the foundation of the building are constructed.
5. Hole or Pit excavation
The design of the substructure may require hole or pit to be excavated (example: isolated column base) in case of a circular hole, hand or mechanically driven anger or drilled are used. Puts being small shallow or a rectangular hole may be excavated mechanically by hand.