How to Check a Wind Turbine Foundation Design: the Chinese Standards Stack (NB/T 10311-2019 Onshore, NB/T 10105-2025 Offshore Replacing the 2018 Edition from 18 June 2026, GB 50021 Geotechnical Investigation), IEC 61400-6:2020 and Its 2025 Amendment, IEC 61400-1 and the Nine Items DNV-ST-0126 Gives Requirements For

Short answer. A foundation design package for a wind farm in China should name its governing standard and show that the standard is the current one. For onshore turbines that is NB/T 10311-2019 陆上风电场工程风电机组基础设计规范, in force since 1 May 2020, which also requires compliance with other current national standards. For offshore turbines the 2018 code NB/T 10105-2018 is recorded as withdrawn with effect from 18 June 2026, the date its replacement NB/T 10105-2025 takes effect for new, rebuilt and expanded offshore projects. The ground data behind the design come from a geotechnical investigation under GB 50021-2001 (2009 edition). Internationally, IEC 61400-6:2020 (amended June 2025) sets requirements for the structural integrity of onshore support structures including foundations and the geotechnical assessment of the soil, within the IEC 61400-1 design framework. DNV-ST-0126 (2021), written among other objectives to serve as a contractual reference between suppliers and purchasers, gives requirements for design principles, materials and inspection, loads and load combinations, load-effect analysis, structural design, corrosion protection, geotechnical design, grouted connections and scour protection — CNWattHub reading: that list is a usable table of contents for a buyer's review. None of the standard texts was read for this guide; it cites records, abstracts and DNV's public excerpt, and says where the clauses are.

1. The Chinese standards stack

The records also point to the surrounding documents a reviewer will meet: for onshore, T/CCPA 43-2023 陆上风电机组地基基础加固技术规程 (a 2023 association standard on foundation reinforcement) and NB/T 31113-2017 on construction organisation design; for offshore, NB/T 10920-2022 on foundation safety-monitoring design, NB/T 11086-2023 on composite bucket foundations and NB/T 10906-2021 on onshore foundation construction.

Three points of status matter for a package dated 2026. First, the onshore code's stated purpose is design that is 'safe and serviceable, economical, technically advanced and environmentally friendly', and it applies alongside, not instead of, current national standards. Second, an offshore design that still cites NB/T 10105-2018 for work after 18 June 2026 is citing a withdrawn code. Third, the geotechnical investigation code GB 50021 dates from 2002 (2009 edition), and its record lists the 2021 general code GB 55017-2021 as a current related standard; a reviewer should ask which the investigation report followed.

2. The IEC frame

IEC 61400-1:2019 'specifies essential design requirements to ensure the structural integrity of wind turbines', covers all subsystems including support structures, applies to turbines of all sizes and refers to IEC 61400-3-1 for additional offshore requirements. IEC 61400-6:2020 then 'specifies requirements and general principles to be used in assessing the structural integrity of onshore wind turbine support structures (including foundations)'; its scope includes 'the geotechnical assessment of the soil for generic or site specific purposes', the strength of flanges and connections to the rotor-nacelle assembly (designed to this document or to IEC 61400-1) and 'all life cycle issues that may affect the structural integrity such as assembly and maintenance'. Amendment 1 was published on 13 June 2025 (TC 88, 88 pages) and a consolidated IEC 61400-6:2020+AMD1:2025 version exists.

CNWattHub reading: a foundation designed to IEC 61400-6 should state whether it was designed to the 2020 text or the 2025 consolidated version, and a turbine supplier's foundation load document should say which IEC 61400-1 edition its loads come from.

3. The nine items DNV-ST-0126 gives requirements for

DNV-ST-0126 (December 2021) is written, among other objectives, 'to serve as a contractual reference document between suppliers and purchasers related to design, construction, installation and in-service inspection'. It can be used for steel and concrete towers, gravity-based concrete foundations, monopiles, jackets and suction buckets, and 'gives requirements for the following: design principles; selection of material and extent of inspection; selection of design loads and load combinations; load effect analyses; structural design; corrosion protection; geotechnical design; grouted connections for offshore support structures; scour protection for offshore support structures'. It applies to all onshore and fixed offshore support structures.

Its definitions are useful vocabulary for a review. A foundation is 'structural or geotechnical component, or both, extending from the ground level or the seabed and downwards'; design life is the period over which the structure is designed to meet the standard's requirements; fatigue limit states are 'possibility of failure due to the cumulative damage effect of cyclic loading'. Its contents include a resonance assessment (3.6), serviceability loads and requirements (3.10), transportation and installation loads (3.13) and a geotechnical design section (Section 7). Only the public 32-page excerpt (changes, Section 1 and definitions) was read; the design sections themselves were not.

4. A review sequence built from the sources

The sources above do not give numbers — no bearing capacity, settlement or stiffness limit is quoted here — but they do give the structure of a complete package. CNWattHub's reading of them as a checklist (DNV-ST-0126's list is DNV's own scope, used here as a reviewer's prompt, not as a requirement on other standards):

1. Governing standard and edition. Onshore: NB/T 10311-2019. Offshore: NB/T 10105-2025 for work after 18 June 2026. IEC: 61400-6:2020 with or without AMD1:2025.
2. Geotechnical investigation. Which code (GB 50021-2001 (2009) and/or GB 55017-2021), and whether the IEC 61400-6 soil assessment is 'generic or site specific'.
3. Loads and combinations. The IEC 61400-1 edition behind the turbine supplier's foundation loads; the load combinations and load-effect analysis in the design.
4. Design principles and limit states. Fatigue limit states (cumulative cyclic damage) addressed alongside strength and serviceability; resonance assessed.
5. Design life. Stated and consistent with the turbine's planned lifetime.
6. Durability and marine items. Corrosion protection; for offshore, grouted connections and scour protection.
7. Life-cycle issues. Assembly, transportation/installation loads and maintenance covered, as IEC 61400-6 and DNV-ST-0126 both require.
8. Monitoring. For offshore, the related standard NB/T 10920-2022 on foundation safety-monitoring design is listed with the 2025 code; ask whether monitoring was designed in.
9. Reinforcement history. For existing onshore foundations, T/CCPA 43-2023 on foundation reinforcement exists; ask whether any reinforcement was done and to which document.

5. Reading table

Scope limits

This guide reads catalogue records of four Chinese standards, three IEC webstore pages and DNV's public excerpt of DNV-ST-0126. It quotes no clause of any Chinese or IEC foundation standard, no soil parameter, load factor, stiffness or settlement limit, and no project document. GB 50007 (building foundation design) was not retrieved. Standards records change; the withdrawal and effective dates quoted are those shown on the records on the retrieval date.