The Foundation of a Structure is very important care is to be taken to see that the excavation for Foundation is carried out methodically. Let’s take a look how the excavation is done in gravelly soils. Foundation is the important part of all structure used to transfer the loads of a building on a firm soil deep down in the ground.
The movement or settlement of the foundation result in cracks in the building. The layout of the foundation is to be correctly marked on the ground before taking up the excavation. The excavation shall be done true to the level, slope,shape and pattern.
The Bed of excavation in foundation pits and trenches shall be of the correct level and consolidated by watering and ramming. Any Excavation done to extra depth should be filled with lean concrete consisting of 1 part of Cement. 4 Parts of sand and 8 Parts of Stone aggregates in all types of soils. Soft and defective spots on the bed of the foundation shall be dug out and filled with concrete.
The excavation should be taken to a minimum depth of 1 to 1.2 m in ordinally soils for 2-3 story buildings. It shall be preferably taken down into a firm soil and below the layer affected by water penetration. The Excavated material must be deposited away from the pit, to prevent collapsing of edges. For Deep foundation the excavation should be bridges with tight storing to prevent collapsing of signs.
Summary Excavation in Gravelly Soils
Care should be taken which excavating
Excavation shall be done to the required level, slope and shape.
Bed of excavation should be consolidated by watering and ramming
Minimum depth of excavation should generally be 1.2 m.
Sides of the deep foundation should be shored and braced.