Footing Excavation for Foundation of Manufacturing Plant
Footing
Footing is a structure constructed in brick work, masonry or concrete under the base of a wall or column for distributing the load over a large area.
Width of Foundation/Footings
The width of footings should be laid according to structural design. For light loaded buildings such as houses, flats, school buildings etc having not more than two storeys, the width of foundation is given below.
1. The width of footing should not be less than 75 cm for one brick thick wall.
2. The width of footing should not be less than 1 meter for one and half brick wall
Footing Excavation
Excavation was carried out both manually as well as mechanically. Normally 1-2 earth excavators (JCB’s) were used for excavating the soil. Adequate precautions are taken to see that the excavation operations do not damage the adjoining structures. Excavation is carried out providing adequate side slopes and dressing of excavation bottom. The soil present beneath the surface was too clayey so it was dumped and was not used for back filling. The filling is done in layer not exceeding 20 cm layer and than its compacted. Depth of excavation was 5’4” from Ground Level.
Footing Excavation details
Precautions during Excavation of Foundation Work
The depth and width of foundation should be according to structural design.
1. The depth of the foundation should not be less than 1 meter in case the design is not available.
2. The length, width and depth of excavation should be checked with the help of center line and level marked on the burjis.
3. The excavated material/ earth should be dumped at a distance of 1 meter from the edges.
4. Work should be done on dry soil.
5. Arrangement of water pump should be made for pumping out rain water.
6. The bottom layer of the foundation should be compacted.
7. There should be no soft places in foundation due to roots etc.
8.Any soft/ defective spots should be dug out and be filled with concrete/ hard material
Foundation
Foundation is the part of structure below plinth level up to the soil. It is in direct contact of soil and transmits load of super structure to soil. Generally it is below the ground level. If some part of foundation is above ground level, it is also covered with earth filling. This portion of structure is not in contact of air, light etc, or to say that it is the hidden part of the structure.
Depth of Foundation
Depth of foundation depends on following factors.
1. Availability of adequate bearing capacity
2. Depth of shrinkage and swelling in case of clayey soils, due to seasonal changes which may cause appreciable movements.
3. Depth of frost penetration in case of fine sand and silt.
4. Possibility of excavation close by
5. Depth of ground water table
6. Practical minimum depth of foundation should not be less than 50 cm. to allow removal of top soil and variations in ground level.
7. Hence the best recommended depth of foundation is from 1.00 meter to 1.5 meter from original ground level