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Part B - Certificates and approval requirements
This procedure is essential for all certificates
• in which soil deformations are contained as a target or influencing parameter
• in which changes in the soil properties have to be considered
• in which assumptions are made regarding model parameters due to the lack of determinability
To the extent that soil deformations are relevant in terms of the design but cannot be predicted with the
necessary level of accuracy, the resulting problems shall be bypassed using suitable design measures
if circumstances permit. Otherwise, the observation method is to be used.
3.2.4.2 Safety certificate concept and process, level of stability against collapse
Geotechnical certificates of the structural safety of the soil, the foundation elements and their components
shall be obtained for offshore wind turbines in accordance with the following principles:
• The mechanisms of the expected interaction between the soil and the structure shall be represented
and considered in the certificates for the foundation elements.
• In all cases, a certification concept with characteristic soil parameters and partial safety factors on
the load side and the resistance side (load and resistance factors) shall be used. Deviations are
permitted in justified cases, in particular if the interaction between the soil and the structure does
not permit definitive separation between load and resistance or if the resistances are directly or
indirectly dependent on external effects (e.g. shearing resistances of external loads). In such cases,
a comparable level of stability against collapse shall be demonstrated.
• The applicability of the certification process used shall be documented. Violations of the documented
application limits shall be evaluated and documented.
• To the extent that recognised certification processes are unavailable and a separate calculation
model with calculation processes is designed, the model and the calculation process shall be presented
in a way that permits it to be tested and be comprehensively documented. If the calculation
results achieved through this method are not without doubt and no major safety reserves in the
structure are indicated for the problem being dealt with, then the applicability of the model, the
process itself and its assumptions in the application case shall be verified by a suitable measurement
and observation programme on the structure. These measurements and observations form a
necessary component of the certificate and shall be presented as such together with the certificate;
this process corresponds to the „observation method“ in accordance with EC7 [20], its elements
shall be implemented in full (see Appendix 3).
• Deviations from the level of stability against collapse in accordance with DIN 1054-2005.01 [19] are
basically permitted for considering the special conditions of the offshore situation, any such deviations
shall be indicated and justified. Lower deviations from this level of stability against collapse
shall require the approval of the BSH, which may engage the services of a suitable assessor for this
purpose. If different safety concepts and certification processes are used, equivalence of the safety
statement shall be confirmed by an expert.
3.2.4.3 Technical codes of practice
The following technical codes of practice shall be used as the basis, as necessary in the updated version
at the time when the design basis is defined:
f11 „Standard for Geotechnical Site and Route Surveys“
f201 DIN EN 1997-1:2005-10
f 191 DIN 1054:2005-01
Deviations from these codes of practice are permitted in order to consider the special conditions
of offshore wind turbines. They shall be indicated as such and justified. Final approval of the BSH
is required for the deviations, and the BSH may engage the services of a suitable assessor for this
purpose.
