Anchor Deep Foundations Wind Turbine Foundation

Anchor Deep Foundations

The P&H rock or pile anchor foundation is a proprietary (patent pending) foundation used to support large wind turbines. The P&H anchor foundations consist of a 5-foot thick, 24-foot diameter, reinforced concrete mat (cap) supported by commonly 12 to 20, 35 to 50-feet long anchors aligned within a typical 20-foot diameter circle. Large wind turbines greater than 2 MW may require more anchors and a double row.

Large 2-½ inch diameter rods are used as the anchors. The number and length of anchors are based on the magnitude of applied loads at the top of the foundation as well as the soil and rock conditions. The pile or rock anchors are installed by drilling a shaft and the anchor rod is inserted and grouted. Post-tensioning is used to develop an internal tension force in each anchor. The intention is to have enough tension in the rod to reduce foundation deflections from normal wind loading.

The large overturning moments induced by the wind turbine are resisted by friction (bond stress) along the length of the anchors. The anchors are post-tensioned to create a compression stress on the subgrade beneath the cap. The post-tension load resists the overturning moment by creating a built-in clamping force to keep the cap in place. The higher the pre-tensioning of the anchors results in a higher moment capacity of the foundation. The post-tension load in the anchor is calculated to cover the load imposed by maximum wind forces given by the turbine manufacturer. Normal operational loads do not produce stress reversals in the subgrade/concrete interface or the anchor so there is no substantial fatigue or cyclic degradation of the soil or rock.

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Engineering Drawing:

 

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Anchor Deep FOUNDATION

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Advantages of the Anchor Deep Foundations

  • Ability to support the largest available turbine systems
  • Anchor foundation systems excel in every soil type
  • Reduced footprint and site disturbance
  • Reduction and potential elimination of blasting requirements
  • Increased stiffness and long-term reliability
  • Maximizes material and resource efficiencies
  • Superior for mountain and remote access sites

Anchor Deep Foundations Flier

Wind Energy Projects Built with P&H Anchor Foundations

No. Year Built Project Location State/Prov Turbine Type Tower Height (m) No. of Turbines Turbine Size (MW)
1 1998 Vanscycle Vansycle, OR OR Vestas V-47 660kW 50 38 0.66
2 2004 Guantanamo Bay US Naval Base Guantanamo Bay, Cuba   NEG-Micon 950 kW 55 4 0.95
3 2006 Hull 2 Hull, MA MA Vestas V-80 1.8 MW 80 1 1.80
4 2006 Forest Creek Big Spring, TX TX Siemens 2.3MW 80 54 2.30
5 2006 Sand Bluff Big Spring, TX TX Gamesa G87 2.0MW 78 45 2.00
6 2006 Locust Ridge Mahonoy City, PA PA Gamesa G87 2.0MW 78 13 2.00
7 2006 Mars Hill Mars Hill, ME ME GE 1.5MW 80 28 1.50
8 2008 Mountain Home Mountain Home, ID ID Suzlon S-88-2.1 MW 79.2 20 2.10
9 2008 Wray Wray, CO CO Directwind 54 900kW 38 1 0.50
10 2008 Stetson Mountain Danforth, ME ME GE 1.5MW 80 38 1.50
11 2008 Kent Hills Kent Hills, NB NB Vestas V-90 3.0 MW 80 32 3.00
12 2008 Locust Ridge II Mahonoy City, PA PA Gamesa G87 2.0MW 78 53 2.00
13 2008 Pine Tree Wind Mojave, CA CA GE Wind 1.5 MW 65 80 1.50
14 2008 Lempster Wind Farm Lempster, NH NH Gamesa G87 2.0MW 78 14 2.00
15 2008 Portsmouth Portsmouth, RI RI AAER 1500-77 1.5 MW 65 1 1.50
16 2008 Tin City Tin City, AK AK Vestas V27 225 kW 31 1 0.23
17 2008 Mark Richey Woodworking Newburyport, MA MA Vestas RRB 600 kW 65 1 0.60
18 2009 Porta High School Petersburg, IL IL Vestas RRB 600 kW 50 1 0.60
19 2009 Kibby Wind Power Franklin County, ME ME Vestas V-90 3.0 MW 80 44 3.00
20 2009 Williams Stone Co. East Otis, MA MA Vestas RRB 600 kW 65 1 0.60
21 2009 Fox Island Vinalhaven, ME ME GE 1.5MW 80 3 1.5
22 2009 Stetson II Danforth, ME ME GE 1.5MW 80 17 1.5
23 2009 Berkshire Hancock, MA MA GE 1.5MW 80 10 1.5
24 2009 Pine Tree -additional (10) Mojave, CA CA GE Wind 1.5 MW 80 10 1.5
25 2010 Conneaut School & WWTP Conneaut, OH OH Turbowinds T600/T400 65 2 0.5
26 2010 Vestas Manfacturing Facility Pueblo County, CO CO Vestas V100 80 1 1.8
27 2010 Tooele Army Depot Tooele, UT UT CPC 1.5MW 78 1 1.5
28 2010 Kent Hills II Kent Hills, NB NB Vestas V-90 3 MW 80 18 3.0
29 2010 MWRA Delauri Pump Station Charlestown, MA MA SL 1500 70 1 1.5
30 2010 Testa Produce Chicago, IL IL Norwind 750 KW 55 1 0.8
31 2010 Danbury Local School Marblehead, OH OH Northwind 100 37 1 0.1
32 2011 Kingman Kingman, AZ AZ Gamesa G90 2-MW 69 5 2.0
33 2011 Granite Reliable Dummer, NH NH Vestas V-90 3 MW 80 33 3.0
34 2011 BHE Bus Stop Lafette, IN IN Northwind 100 37 1 0.1
35 2011 Rollins Mountain Lincoln, ME ME GE 1.5MW 80 40 1.5
36 2011 Record Hill Record Hill, ME ME Siemens 2.3 MW 80 22 2.3
37 2011 Zotos Geneva, NY NY Wintec 1650 KW 80 2 1.7
38 2011 NCCI-MWCC Gardner, MA MA Vestas V82 80 4 1.7
39 2011 Scituate Wind Scuitate, MA MA Sinovel SL 1500 80 1 1.5
40 2011 Anhueser-Busch Fairfield, CA CA GE Wind 1.5-77 65 1 1.5
41 2011 Kingston Landfill Kingston, MA MA Hyundai DF2000 80 1 1.7
42 2011 Gilbane, NBC Narragansett Bay, RI RI Goldwind 82-1500 80 3 1.5
43 2012 Scituate Scituate, MA MA Sinovel SL 1500 80 1 1.5
44 2012 UMass Dartmouth, MA MA Turbowinds T600 50 1 0.6
45 2012 Fairhaven Wind Fairhaven, MA MA Sinovel SL 1500 80 2 1.5
46 2012 UTB Brownsville, TX TX Northwind 100 37 1 0.1
47 2012 Bull Hill East Brooke, ME IN Vestas V100 95 19 1.8
48 2012 Kingdom Community Wind Lowell, VT VT Vestas V112 84 21 3.0
49 2012 Varian, Gloucester, MA Gloucester, MA MA Vestas V100 80 1 1.8
TOTAL FOUNDATIONS BUILT 694