Newly constructed wind turbines often require instrumentation to verify the design and long-term performance of their foundations. For piled foundations, sister bars, strain gages and incremental extensometers are often used to measure load distribution along the pile, and in-place inclinometers (installation shown at left) are used to measure deflections during any pile testing programs undertaken to efficiently design the pile dimensions. The same sensors can be used to monitor loads in the piles, in near real-time, and load cells can be employed to monitor the effectiveness of any lock off bolts. For raft foundations, tiltmeters, earth pressure cells, deformation gages, differential settlement systems and multiple position borehole extensometers can be installed to detect tilting and to monitor any separation or movement between the foundation and the underlying soil/rock material. Biaxial tiltmeters, strain gages, and dynamic strain transducers are useful to measure any tilting and distortions of the tower. Dataloggers are used to gather and transmit information and data, via the internet, to provide near real-time data display and monitoring at any location using Vista Data Vision software.
An extensive monitoring program comprising a series of vibrating wire load cells and automatic data acquisition systems has been deployed on a number of wind turbine foundations to measure tie-down anchor loads.
Photographs courtesy of Cianbro Corporation, Maine, USA.
GEOKON welcomes Case History contributions. If you have a project you would like to be considered for inclusion in our Case History section, please submit details along with 2 or 3 suitable images to the GEOKON Web Manager.