2.4.2 Actions

(1)P The definition of actions shall be taken from EN 1990:2002. The values of actions shall be taken from EN 1991, where relevant.

(2)P The values of geotechnical actions to be used shall be selected, since they are known before a calculation is performed; they may change during that calculation.

NOTE Values of geotechnical actions may change during the course of calculation. In such cases they will be introduced as a first estimate to start the calculation with a preliminary, known value.

(3)P Any interaction between the structure and the ground shall be taken into account when determining the actions to be adopted in the design.

(4) In geotechnical design, the following should be considered for inclusion as actions:

  • the weight of soil, rock and water;
  • stresses in the ground;
  • earth pressures and ground-water pressure;
  • free water pressures, including wave pressures;
  • ground-water pressures;
  • seepage forces;
  • dead and imposed loads from structures;
  • surcharges;
  • mooring forces;
  • removal of load or excavation of ground;
  • traffic loads;
  • movements caused by mining or other caving or tunnelling activities;
  • swelling and shrinkage caused by vegetation, climate or moisture changes;
  • movements due to creeping or sliding or settling ground masses;
  • movements due to degradation, dispersion,decomposition, self-compaction and solution;
  • movements and accelerations caused by earthquakes, explosions, vibrations and dynamic loads;
  • temperature effects, including frost action;
  • ice loading;
  • imposed pre-stress in ground anchors or struts;
  • downdrag.

(5)P Consideration shall be given to the possibility of variable actions occurring both jointly and separately.

(6)P The duration of actions shall be considered with reference to time effects in the material properties of the soil, especially the drainage properties and compressibility of fine-grained soils.

(7)P Actions, which are applied repeatedly, and actions with variable intensity shall be identified for special consideration with regard to, e.g. continuing movements, liquefaction of soils, change of ground stiffness and strength.

(8)P Actions that produce a dynamic response in the structure and the ground shall be identified for special consideration.

(9)P Actions in which ground- and free-water forces predominate shall be identified for special consideration with regard to deformations, fissuring, variable permeability and erosion.

NOTE Unfavourable (or destabilising) and favourable (or stabilising) permanent actions may in some situations be considered as coming from a single source. If they are considered so, a single partial factor may be applied to the sum of these actions or to the sum of their effects.