Helical piles – 220/66 kV sectioning substation – Lastarria

Goals
At the height of the municipality of Loncoche, in the IX Region of La Araucanía, Chile, the substation sections the Cautín – Ciruelos 220 kV line and the Temuco – Loncoche 66 kV line, with the aim of improving the electrical infrastructure in the La Araucanía region.
AXIATECH was requested by EDEMSA Chile, in charge of the construction of the New Lastarria Substation, for the execution of the engineering, supply and construction of the foundations of the substation's structures and yard equipment.
In view of the technical challenges that the typology of the project and geographical location required, it was necessary to carry out an investigation of the state of the art and practice in terms of foundations, resulting in the selection of the alternative of helical piles as the choice with the greatest advantage. technical and economic for the construction of the project foundations.

CONVENTIONAL SOLUTION
In a geological context, the project area is located on fluviolacustrine deposits made up of sand and clay, the water table levels, even in the summer season, are close to the surface, configuring a quite complex and challenging geotechnical and soil mechanics scenario. The stratigraphic profile is mainly composed of highly compressible, saturated soils with considerable organic matter content, which requires thinking about special and deep foundations in order to eliminate future problems of settlement and deformation.
In addition to the aforementioned, we cannot leave aside an important issue that directly affects the performance of the foundations and that is the seismic complexity that any construction located in Chilean territory represents. In fact, the Lastarria substation is located just 88 km from the city of Valdivia, the place where the epicenter of the largest earthquake in the history of humanity has been recorded.
En virtud de lo anterior, era obligatorio concebir cimentaciones profundas para atender las solicitaciones de carga y la demanda sísmica.
However, the geographical location and the nature of the soils configured onerous construction scenarios to carry out the project. Additionally, the times required for construction exceeded the project's expectation for its commissioning.

SOLUTION WITH HELICOIDAL PILES
Helical piles were an excellent alternative to overcome the challenges imposed by the project and its conditions. However, since it is the first substation in Latin America to adopt new foundation techniques and alternatives, it was necessary to support the performance of the selected foundation under the different stresses through a high-level engineering process and a subsequent field testing phase. .
With the interaction of a multidisciplinary group of engineers specializing in different areas, with sufficient experience in the sector, additionally with the interaction with professionals from EDEMSA and TRANSELEC, we satisfactorily overcome all engineering challenges.

Additionally, thanks to the in-depth and well-supported engineering work, through a field testing campaign it was possible to assertively calibrate the mathematical models and hypotheses used in the design phases, resulting in the acceptance, implementation and approval of the alternative. Helical piles as a preferred foundation technique in energy transmission and distribution projects in Chilean territory.

RESULT
During the construction phase and thanks to the implementation of installation, verification and testing protocols; In addition to state-of-the-art installation and measurement equipment with the help of highly trained personnel for the development of the construction, from the execution and control of the project it was possible to achieve the challenging milestones set in the programming phase. Likewise, the quality control of the helical pile foundation system for both the supervision and the owner of the project, allowed the work to be received satisfactorily without objections and non-conformities.
Similarly, thanks to the implementation of protocols and the experience of the personnel designated for the execution of the project by Axiatech, at the time of completion of the work, no accidents or any type of claims associated with health and safety were recorded in the work.
Finally, compared to the conventional solutions initially contemplated, a significant reduction in construction times was obtained, in addition to a dramatic reduction in the environmental impact, in terms of CO2 emissions.
Thanks to all the advantages described, we can proudly affirm that the helical pile foundation solution provided by Axiatech is the best technical, economic, logistical, safe and environmental alternative for your project.