Foundation Parameter Setting (FDGroup Page)

  • Calculation type

    Foundation optimization: Through automatic iteration, optimization, and verification, Greenwich output the most economical and reasonable foundation scheme based on geological and load data, boundary parameter and optimizing region set by user.

    Foundation check: If you have a validated foundation scheme, select Base Checking to define foundation size and file foundation placement parameters. Greenwich calculates and outputs various verification results for the specific scheme.

  • Connection type

    Generally, select anchor as the connection between turbine foundation and tower (for Envision self-built projects). If wind farm owner has specific need, select the connection type he need. The material specifications of base ring and anchor should be defined according to turbine type parameters as power production, hub height, maximum bending moment, etc.

  • Platform type

    Only extended platform is supported in Greenwich foundation design. The lattice platform is not supported.

  • Subgrade type

    The design and optimization of natural subgrade (extended foundation) and pile foundation are supported in Greenwich foundation design. Pile foundation consists of precast pile and caisson pile. Select subgrade type according to the following conditions:

    • Select subgrade type recommended by existing feasibility study report or geological exploration unit.
    • Select extended foundation when the load characteristic value is beyond 300kPa at the depth of 5m or when there is bed rock.
    • For turbines located around water area as pond or river or for foundation located on relatively thick soft soil layer (such as mucky soil) at the depth of 10m, select pile foundation.
    • Select extended foundation when the load characteristic value is below 200kPa at the depth of 5m and hub height is above 100m.
    • Under common conditions, pile foundation is recommended for plain region and extended foundation for mountainous region.
    • Pile type selection: select precast pile in most cases When the powder sand layer is thick or standard penetration test blow count of clay is larger than 20 and that of sand is larger than 40 at the depth of 20m of subgrade, caisson pile is recommended because of difficulties in pile sinking.
  • Pile foundation parameter
    • Precast pile: Select tubular pile with the external diameter of 500 or 600 mm in common situations. The most commonly used model is PHC-II600B110.
    • Caisson pile: The pile diameter is 600 - 1000 mm in common situations. The most commonly used size is 800 mm.
    • Pile length: Optimize the length of caisson pile within the default range. The construction of precast pile might encounter pile sinking. It is recommended to optimize the upper and lower limit of pile length according to the bearing layer buried depth or pile length specified in the geological exploration material.
  • Foundation size
    • For foundation size, adopt the default values of upper and lower limit in common situations.
    • Adjust lower limit of the bottom board edge height according to the owner's regulation when requested.
    • If some margin is needed in the foundation design, adjust the bottom board edge height as 0.9 m, 0.95 m, or 1.0 m according to the actual situation.
    • If there is rock subgrade, reduce the upper limit of foundation buried depth in a proper proportion to minimize the excavation difficulty in construction.
  • Other commonly-used parameters
    • Adopt the default values for commonly-used parameters in common situations. For some of them, edit the values according to actual situation.
    • If some margin is needed in the foundation design, for extended foundation, set the upper limit of zero stress zone at foundation bottom under frequent earthquake condition as 0%.
    • If some margin is needed in the foundation design, the upper limit of ratio of bottom board width and height should be set as 2.5.
    • The value of slope excavation ratio should be set according to that recommended in geological exploration material or Table 6.7.2 in Code for Design of Building Foundation. Generally, adopt the default value 1:0.75 (1.33333).
    • If it is requested to design a foundation radically, for extended foundation, excavate the bottom board to reduce the concrete construction quantity. Set the bottom board hollow radius as 1.7 m.
    • Generally, select line outer type as tower line outer.