Anchor Cage System From LT
Longteng has a proven track record supplying anchor cage system for onshore wind turbine foundations under Gold Wind, Envision, ReeWind, GE and other manufacturers turbines.
Longteng supplies anchor cage bolt with excellent anti-delay fracture performance and long fatigue life(no damage after 12 million times test); Provide double thread bolts with maximum length of 12000mm.
In order to develop low wind speed region, tower height of wind turbine is constantly increasing, and the connection method between tower and foundation has also changed, original base ring connection has been replaced by anchor cage system connection, which avoids occurrence of stress concentration phenomenon at the connection of basic ring.
Anchor Cage Foundation Structure
Anchor Cage Model Made for Exhibition
With prestressed anchor bolt replaces base ring, and the form of wind turbine foundation is still in usual basic form. While there is a difference: anchor cage foundation form is not just pouring anchors and concrete together, it is composed of upper anchor plate, lower anchor plate, anchor bolt, PVC protective pipe, etc., and use PVC pipe between the upper and lower anchor plate to isolate anchor bolt from the concrete and with seal method. Thus during pouring process, to avoid corrosion of anchor bolt by prevent water entering protective PVC pipe.
Wind Turbine Anchor Cage Foundation Parts:
High duty wind turbine tower shall have high strength anchor cage foundation system, which includes following components: anchor bolts, upper and lower anchor plate(embed and template ring), splice plates, nuts, washers, PVC sleeves, protective caps, heat-shrink tubes, support stand bolt assemblies, etc.
According to different drawings and technical requirements, there will be different quantities, dimensions, properties, payment terms, shipment, etc. In some cases, the upper ring,(which is also called alignment ring) will be removed after the lower ring (which is also called embedment ring) and anchor bolts were installed and grouted. Then the tower bottom Flange will be fastened with those anchor bolts. Although the install methods are different between full cage or no upper ring cage, the fastening parts are the same.
Anchor Cage Foundation Work Principle:
When anchor bolt is subjected to tension, the up side of lower anchor plate will be evenly stressed. anchor cage bolt has an elastic body, and there is no interface between the elastic portion and the rigid portion, thereby avoiding stress concentration. Due to prestressing of anchor bolt, concrete foundation is always under pressure, so wind turbine foundation using prestressed anchor bolt is protected from stress concentration of concrete on anchor plate of cage foundation.
There are many factors can influence the wind tower foundation configuration, wind turbine size and brand, site geotechnical conditions, etc. Wind tower cage foundation structure has to with stand compressive and uplift forces caused by strong wind forces. Before construction, investigation and research of structural and geotechnical design checks are needed.
Advantages of Prestressed Anchor Cage:
Prestressed anchors cage is used to connect the wind tower and foundation to solve basic ring foundation problems as stiffness, strength abruptness and durability issues.
- Anchor bolt penetrates the entire foundation height and fastens it to foundation floor through lower anchor plate(embed ring plate). The steel structure formed is continuous, without stiffness and sudden change in strength;
- Cross-arrangement of steel rebars and anchor bolts does not influence each other, construction work is easy, and anchor cage foundation has good integrity;
- The hydraulic double-cylinder high-strength bolt tensioner is used to apply accurate pre-tension to anchor bolt, so that the upper and lower anchor plate exert pressure on reinforced concrete. When foundation is bent, the compressive stress on windward side is released but is always subject to state of under pressure, concrete does not crack, it has advantages: improve durability of concrete; improve anchoring force of concrete to beams and slabs.
- Vertical reinforcement in foundation pier is almost unstressed. It is only necessary to use non-prestressed reinforcement rebar, and the anchor cage foundation construction is more economical;
- The production and supply cycle of anchor bolt assembly is short, which can greatly reduce construction period and accelerate investment return.