Shallow Foundation – It’s type and benefits
Foundation is categorized as Deep foundation and Shallow or Open foundation on the basis of the depth of foundation set up.
A deep foundation (under 10 or more meters) is provided on a soil that is not solid and remains significantly under the lowest part of the superstructure devoid of upper stratum of soil since that soil is not solid and a superior soil.
A shallow foundation is provided on a hard soil adjacent to the ground, and underneath the lowest part of the superstructure, normally 1 m to 5-6 m.
If the foundation is set up directly under the lowest part of the super structure, it is known as shallow foundation. In a shallow foundation, the depth from the ground surface to the bottom of the foundation remains under five times the width of the foundation.
The shallow foundation is suitable for all small buildings and arranged with open excavation by providing natural slopes on all sides.
This type of foundation is useful for a depth up to 5 meter and is generally adapted over the water table.
Purpose of Shallow Foundation: The objective of shallow foundation is to allocate the structural loads over an extensive horizontal area at shallow depth under the ground level. Shallow foundation is suitable for foundations with depth as equivalent to foundation width or where depth is under the width.
Benefits of Shallow Foundation:
• Fewer excavation is required and as a result the labour cost of excavation work is significantly decreased.
• The construction of shallow foundations is uncomplicated since the depth of setting up the foundation is fewer.
• Equipments necessary for building up shallow foundation are easy and also less expensive.
• Less time is required to erect shallow foundation that also facilitates to minimize the cost of hiring equipment and labor.
• Construction of shallow foundations will produce fewer disturbance to geo-surface and therefore, it is perfect for ecology and environment.
• It allows minimizing settlement, when the soil is compressive.
• The cost is minimized as no piling is necessary.
• There is less dubiousness in forecasting of behavior of shallow foundations and supporting soil.
Shallow foundations are again subcategorized into the following types depending on their shape, size and general configuration.
• Spread Footing
• Combined Footing
• Mat or raft Foundation
• Grillage Footing
• Eccentrically Loaded Footing