Execution of Bored Piles Under Polymer Support – Sustainable and Flexible Concept for a Mega Project

The future city ""The Line"", NEOM, Saudi Arabia is currently the largest construction site in the world. Large-scale bored piles with depths of up to 80 m are installed for the foundation in accordance with EN 1536, where stabilization of the borehole must be ensured. Drilling under protection of casing has technical limits depending on the depth and is increasingly uneconomical at greater depths and thus has been replaced by drilling under fluid support. With regards to practical experiences on the NEOM project and others, significant differences are shown between design and execution of bored piles by means of stabilization with bentonite suspension or ""polymer support"", which is increasingly being used, especially internationally. An assessment based on performance data and scientific know-how has shown to be essential for the design of the right support fluid and the choice of suitable plant, equipment and handling on site. The adjustment and optimization of the properties of the support fluid as well as the ""handling"" and quality assurance on the construction sites will be discussed. Special focus is given to: 1. Criteria for the quality assurance plan, 2. Measures to prevent excessive loss of support fluid, Furthermore, the aspects of sustainability and flexibility in the use of polymer support fluids are also discussed in detail.