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Appendices 
Appendix 3 Application notes for geotechnical verifications 
Appendix 3-1 Consideration of cyclic loads in the design of foundation elements 
3-1.1 Preliminary remarks 
With all foundation types presently considered, cyclic loads acting on the foundation elements 
and conducted into the foundation soil reduce the bearing capacity of the foundation and lead 
to accumulated deformation. Depending on local conditions, unfavourable changes of pore 
water pressure are possible which may lead to soil liquefaction. 
To assess possible changes of the bearing capacity of foundation elements, a planning expert 
and a geotechnical expert with special knowledge in this particular field shall be commissi 
oned. 
Within the scope of the obtaining the 1 st release from the BSH, the concept for incorporating 
cyclic loading in the design of foundation elements for the supporting structure and an expla 
nation of the inspection programme planned to be carried out have to be provided. 
As part of the 2 nd release process, verification has to be provided that cyclical loading has 
been taken into account, which includes the documentation of laboratory and field tests con 
ducted in that context. 
3-I.2 Cyclic loads on offshore wind turbines 
3-I.2.1 Design event 
The foundations of offshore wind turbines are continually subject to the non-static impacts of 
wind, waves and operation loads acting on the support structure. To establish the loads on 
the support structure of the wind turbine, please refer to chapter B3.3.1.2. Cyclic loading has 
to be included in the verification of bearing capacity by calculating a storm event as described 
in the following, also taking into account the other load cases. A special operating condition 
causing major cyclic loading of the foundation elements may also have to be included in the 
calculations. 
The potential bearing capacity reduction of a foundation which is subject to cyclic loading du 
ring a major storm event (please refer to Table 3-1.1 and Figure 3-1.1), has to be analysed ta 
king into account the complete load spectrum. The storm event shall include the design ext 
reme value acting on the foundation elements, and the number and distribution of extreme 
values used must be typical of the particular site. The loads thus computed shall be converted 
to the maximum design loads (please also refer to DIN EN 61400-1, Annex F). 
The design event used to verify bearing stability under cyclic loading is described on the basis 
of the definition of design load case DLC 6.1 described in DIN EN 61400-3 and the boundary 
conditions indicated in Table 3-1.1.