Excavation of Building Foundation Trench – Methods of Excavation

Excavation of Building Foundation Trench.

What is Excavation?

This is the remover of the topsoil to a reasonable depth along the foundation line as set out on the profile to get a more firm ground (soil) that can withstand the building load on which the foundation concrete is been laid.

Why Should We Remove Topsoil?

The topsoil of a construction site is been removed due to the following reasons.

  • It contains too much organic material which makes it unstable for building construction
  • To attain a more firm and stable ground for the structure or building
  • It contains loose materials with little or no load –bearing capacity
  • It contains vegetation which can damage the building foundation

This remover should be done to a depth of at least 300 mm below the ground surface depending on the type of structure to be erected and the nature of the soil.

The process of excavation of building foundation trench (topsoil remover) can be carried out with two major methods. These are:

  • Manual method
  • Mechanical method

Excavation of Building Foundation Trench – Manual Method

This is the remover of the topsoil by men using crude tools such as a shovel, spade, digger etc.

The manual method is mostly used in the excavation of domestic building foundation whose area of excavation is not large compared to others such as pavement and industrial buildings. But if the area of the domestic building is large such as estate development, then one or two of the machine mentioned above will be needed alongside with the crude tools. See the figure below.

Excavation of Building Foundation Trench

Excavation of Building Foundation Trench – Mechanical Method

This is the remover of the topsoil by men using machines such as scrapers, bulldozer, grader, face shovel, tractor shovel, skimmer etc.

Excavation of Building Foundation Trench

The mechanical method is widely used in major constructions such as road/pavement construction, high rise buildings, commercial buildings, swimming pool, and underground structures alongside with some crude tools such as the spade and shovel. In both methods, there are major tools and minor tool as stated above. See the figure below

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