Analysis According to EC 7-1 (EN 1997-1:2003)
The bearing capacity of the foundation Rd 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 Sd, unit weight of rock γ, Poisson's ratio ν and uniaxial compressive strength σc. 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.
Type of rock
Pure limestones and dolomites
Carbonate sandstones of low porosity
Oolitic and marly limestones
Well cemented sandstones
Indurated carbonate mudstones
Metamorphic rocks, including slates and schist (flat cleavage / foliation)
Very marly limestones
Poorly cemented sandstones
Slates and schist (steep cleavage / foliation)
Uncemented mudstones and shales
Eurocode 7:Geotechnical design - Part 1:General rules.