Analysis according to EC 7-1 (EN 1997-1:2003)

The bearing capacity of the foundation R_d with a horizontal footing bottom is determined according to a design method for the derivation of expected bearing capacity of spread footings resting on a bedrock outlined in a supplement G (informative) EC 7-1 (EN 1997-1:2003) "Design of geotechnical structures – Part 1: General rules". For low strength or damaged rocks with closed discontinuities including chalks with low porosity less than 35% the derivation of expected bearing capacity follows from classification of rocks into groups of rocks stored in the table below.  The analysis further requires an input of discontinuity spacing S_d, unit weight of rock γ, Poisson's ratio ν and uniaxial compressive strength σ_c. It is assumed that the structure is able to transmit a settlement equal to 0,5 % of the foundation width. The expected values of bearing capacity for other settlements can be estimated using direct proportion. For weak and broken rocks with opened or filled discontinuities it is recommended to use lower values than the expected ones.

Rock groups

Literature:

Eurocode 7:Geotechnical design – Part 1:General rules