Reliability-Based Design and Construction Issues for a Micropile Foundation in Costa Rica

摘要

The paper describes the geotechnical and structural, reliability-based design of micropile foundations for a factory in Costa Rica, along with its construction issues. The chaotic nature of the very loose soil led the designers to substitute micropiles for the driven piles originally called for in the final design. The same chaotic nature of the soil made any deterministic prediction of the pile lengths impracticable, and the designers developed an original and ad hoc reliability-based procedure to cope with the problem. The area was seismically active, with a maximum considered earthquake spectral response acceleration at short periods (0.2 s) equal to 1.04 g. In order to lower costs and to improve the surrounding ground, the micropiles were specially engineered by the designers, who acted as consultants for the foundation specialist subcontractor. The field test gave excellent results, and negligible elastic deformations were recorded up to 1.5 times the design load. This is a positive example of international collaboration among a Costa Rican clienl. a Spanish general contractor, and Italian subcontractors and consultants. The mutual understanding, knowledgeability, and open-mindedness of all parties involved (client, general contractor, subcontractors, designers) resulted in a reliable and cost-effective design and construction.