Abstract
For the first time in research practice, the performance of pile foundations is examined in conjunction with a comprehensive geotechnical assessment of soil conditions during construction on problematic territories. The study is based on the results of technical inspections and aims to identify the causes of deformations in the load-bearing structures of buildings. Particular challenges arise in the development of areas located on the sites of former quarries that were later backfilled with loose, uncompacted soils. The analysis revealed significant errors made during geotechnical investigations, which resulted in unacceptable settlements and structural damage. These findings indicate the need to revise existing design approaches and to strengthen quality control over geotechnical surveys. This issue becomes particularly relevant in the context of the transition to Eurocode-based design, which requires a more accurate adaptation of international standards to local geological conditions.