Soil bearing capacity, soil properties, soil layer friction, rock layer friction, rock bearing capacity, etc., must be available for foundation planning. Depending on the type of foundation, the relevant parameters must be obtained from the geotechnical investigation.
Shallow foundation design
Shallow foundations include footings and slab foundations.
The bearing capacity of the soil must be guaranteed in the foundation design.
The number of tests to be carried out is determined by the engineer based on the area of the building or structural planning.
A ground survey (geotechnical survey) is carried out covering the entire area of the building.
To determine soil resilience, different types of tests are carried out.
To determine the bearing capacity of soil, Mackintosh test, plate stripping test, standard penetration test, cone penetration test, etc. are carried out.
A standard penetration test (SPT) is often performed to assess soil conditions.
This test can be used to determine the classification of the soil beneath the foundation and the thickness of each layer.
If it is ensured that there is no very soft soil, such as peat, beneath the layers, all drilling is generally carried out down to the level of the fresh rock.
Based on the results obtained from soil tests and visual inspection of samples taken during testing, soil parameters are determined.
The maximum load capacity can be determined depending on the dimensions (smaller) and the load of the structure.
Other tests, such as Mackintosh and Plattelager, are not very reliable tests as they have certain accuracy issues. especially the Slab load bearing test does not capture the condition of the underlying layers .
Therefore, if the load is greater and the soil condition appears poor, it is advisable to carry out a test such as standard penetration test (SPT).
Geotechnical investigation for the design of deep foundations
Pile foundations are deep foundations. In principle, a distinction can be made between friction piles that are not anchored in the rock and piles that are anchored in the rock.
In some countries the rock is not close to the ground.
In some countries the depth of the rock is about 400 m.
With this in mind, stakes cannot be driven into rock and it is not absolutely necessary to set the post into rock.
The plie can be terminated where it meets the project requirements.
Soil skin friction and soil end supports at the point where the pile terminates are taken into account in the design if rock termination is not possible.
If the pile can be anchored into the ground, the surface friction of the soil and rock and the ultimate bearing capacity of the rock from the geotechnical study report can be used for the design.
Based on the type of rock/soil, surface friction is determined and the final support capacity of the rock is evaluated through the uniaxial compression test (UFC).
Typically, the well layout is planned based on the area covered by the structure.
Foundation selection can be done as described in the determination article. Type of foundation .
