The Eurocode 7 Bearing Capacity calculation method is detailed in BS EN 1997. The Eurocode 7 bearing capacity method is included simply as one suitable method alongside many others. However as this particular method is detailed within the standard, using the Eurocode 7 bearing capacity method is becoming more and more popular.
The Eurocode 7 Bearing Capacity method is included in the CivilWeb Soil Bearing Capacity Calculation Excel Suite which includes a total of 6 different analytical methods of determining the bearing capacity of soils. Each of these methods is potentially acceptable for use with Eurocode 7, though the Eurocode 7 bearing capacity method itself is often preferred. The CivilWeb Soil Bearing Capacity Calculation Excel Suite can be purchased at the bottom of this page for just £20.
Alternatively the Bearing Capacity Suite is also included in the full Foundation Design Suite which includes all 12 of our foundation design spreadsheets for only £50. This can also be purchased at the bottom of this page.
Eurocode 7 Bearing Capacity Analysis Method
In 2004 the Eurocode for geotechnical design EN 1997-1 included an example method of calculating the bearing capacity of a soil. This is not descriptive as the only acceptable method but the fact that it is included in the standard shows its acceptability in certain conditions.
The Eurocode 7 bearing capacity method generally follows the Vesic method with a few small alterations. It uses Chen’s equation for Nγ which assumes a rough base. BS 8004 presents an alternative method which can allow for a smooth base. Further information on the Vesic method can be found in our Vesic Bearing Capacity article. The Vesic method is also included in the CivilWeb Soil Bearing Capacity Calculation Excel Suite.
The Eurocode 7 bearing capacity calculation method does not allow a depth factor to directly increase the bearing capacity based on the depth and does not allow for foundations on the top of slopes. The depth factors have been found to be unreliable, and for shallow foundations they are relatively small so they have been omitted. This means that the EN 1997-1 method will generate slightly conservative values compared to other methods. The omission of the depth factor makes this method unsuitable for moderately deep foundations.
The standard advises that these conditions should be analyzed from first principles where appropriate. Note that this cannot be omitted in cases where slopes are present as this can lead to an unsafe design.
The Eurocode 7 bearing capacity separates the general bearing capacity equation into two different forms, one for undrained conditions and one for drained conditions. This effectively stipulates separate equations should be used for granular and fine grained soils rather than allowing a single equation with factors which disappear when not applicable.
Eurocode Bearing Capacity Analysis Equations – Drained Conditions
The Eurocode method for drained conditions includes the following equations where;
A’ is the effective plan area of the foundation
B’ is the effective foundation width
L’ is the effective foundation length
D is the embedment depth
q’ is the desive effective overburden pressure at the foundation base
V is the total vertical load acting on the foundation
α is the inclination of the foundation base relative to the horizontal
γ’ is the design effective unit weight of the soil
c’ is the effective cohesion
A diagram is included on the following pages explaining some of these parameters.
Eurocode 7 Bearing Capacity Analysis Equations – Undrained Conditions
The Eurocode 7 bearing capacity method for undrained conditions includes the following equations where;
cu is the undrained shear strength
Eurocode 7 Bearing Capacity Method
The Eurocode 7 bearing capacity method is not intended to be exhaustive. It is simply an example of the analytical techniques which may be acceptable under the standard. However by publishing a particular method this is now likely to be the default bearing capacity analysis method in cases where this method is applicable.
The Eurocode 7 bearing capacity method does not allow for any reductions due to slopes which should be analyzed separately or using an alternative method. The BS 8004 method does include a slope modification factor.
CivilWeb Soil Bearing Capacity Calculation Excel Suite
The CivilWeb Soil Bearing Capacity Calculation Excel Suite includes the Eurocode 7 Bearing Capacity calculation method for both fine grained and coarse grained soils. The spreadsheet suite also includes unique comparison tools which complete the calculations for all 6 methods and present them in a graph for the designer to compare. This allows the designer to complete a full bearing capacity analysis in minutes.
Buy the CivilWeb Soil Bearing Capacity Calculation Excel Suite now for only £20.
Purchase the our Soil Bearing Capacity and Settlement Calculation Bundle for only £25.
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