OHL Presa de Algar
Construction of the Algar Dam: Key Insights
Overview of the Algar Dam Project
- The General Directorate of Hydraulic Works and Water Quality from the Ministry of Environment promotes the construction of the Algar Dam, aimed primarily at recharging overexploited aquifers in Bajo Palancia to restore sustainable system balance.
- The dam will improve flow regulation for irrigation in Sagunto and help control floods, mitigating their effects. The Confederation drafted the project and oversees construction by contractor OHL.
Design Considerations
- Special foundation conditions at the selected site necessitated a design that accommodates Triassic limestones and dolomites with high karstic properties on one side, while less resistant dolomitic materials were found on the other.
- These geological circumstances led to adopting a mixed dam typology; a gravity dam made of vibrated concrete is constructed on one side, housing spillways and drainage elements.
Material Specifications
- Construction began with vibrated concrete containing natural aggregates sourced from riverbeds and flooded terraces, requiring careful washing processes due to environmental constraints.
- A 50% dosage ratio for cement and ash was used, transported directly via continuous conveyor systems to meet environmental standards.
Adaptation to Geological Features
- Variations in material deformability and karst conduits in the right abutment required an adaptive dam typology featuring a flexible internal embankment that ensures stability under these conditions.
- An asphalt core waterproofed this section due to its cohesive flexibility, ensuring structural integrity against potential water migration through well-sized materials ranging from coarse riprap to natural filters.
Quality Control Measures
- Swiss company Wo collaborates with OHL for executing the asphalt core using advanced machinery. Pre-construction studies allowed for precise asphalt mixture dosages ensuring low void indices for impermeability.
- Continuous quality control is conducted by onsite laboratories monitoring mix characteristics through periodic sampling during execution phases.
Layering Process During Construction
- The core is enveloped by transition layers executed simultaneously using specialized machinery capable of laying down up to three layers daily at 20 cm thickness each.
- Proper compaction techniques ensure void indices remain below 3%, crucial for maintaining effective contact between different material layers within the structure.
Monitoring Systems Implemented
- Special cells designed for measuring pressure against contacts are monitored via computer systems, providing real-time data on stress levels transmitted through supports.