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Bearing Capacity on Drained Subsoil

For foundation in drained condition, it is possible to select one of the followings approaches to assess the bearing capacity of the foundation:

• standard analysis
• according to CSN 73 1001 "Základová pùda pod plošnými základy" approved 8.6. 1987
• according to Polish standard PN-81 B - 03020 "Grunty budowiane, Posudowienie bezpošrednie budowli, Obliczenia statyczne i projekktowanie" from year 1982
• according to Indian standard IS:6403-1981 "Code of Practice for Determination of Bearing Capacity of Shallow Foundations" from the year 1981
• according to EC 7-1 (EN 1997-1:2003) "Design of geotechnical structures - Part 1: General rules"
• according to NCMA Segmental retaining walls manual, second edition
• according to Chinese standard GB 50007-2002
• according to Russian standard SNiP 2.02.01-83
• according to Danish standard DS/EN 1997-1 DK NA:2013
• according to DPWH standard "Design Guidelines, Criteria and Standards: Volume 2C – Geological and Geotechnical Investigation - Annex G: Geotechnical Formulas"
• according to Meyerhof
• according to Vesic
• according to German standard DIN 4017
• according to Spanish standard CTE DB SE-C
• according to NZ standard B1/VM4
• according to Russian standard SP22.13330.2016
• according to Czech standard CSN 73 1004

All approaches (with exception of German standard DIN 4017) incorporate coefficients due to Brinch - Hansen (see standard analysis) to account for inclined ground surface and inclined footing bottom.

Assuming drained conditions during construction the soil below spread footing deforms including both shear and volumetric deformations. In such a case the strength of the soil is assumed in terms of effective values of the angle of internal friction φ_ef and the effective cohesion c_ef. It is also assumed that there is effective stress in the soil equal to the total stress (consolidated state). Effective parameters φ_ef, c_ef represent the peak strength parameters.

Owing to the fact that the choice of drained conditions depends on a number of factors (rate of load, soil permeability, degree of saturation and degree of overconsolidation) it is the designer's responsibility to decide, depending on the actual problem being solved, if the effective parameters should be used.

During seismic analysis, the program performs the calculation of bearing capacity for both cases - with and without seismic effect. The resultant bearing capacity is lower from these two values.