Hydrogeochemically Driven Settlement and Stress–Strain Response in Pile Foundations

To accurately assess foundation behaviour under urban conditions, it is essential to integrate geotechnical analysis with continuously evolving hydrogeological parameters. In rapidly developing cities such as Astana, long-term fluctuations in seasonal groundwater levels, salinity dynamics, and changes in soil permeability significantly influence stress–strain behaviour and structural settlement. This study employs multiple software tools, supported by detailed hydrogeological monitoring, laboratory testing, and integrated numerical simulations, to analyse the development of settlement and stress–strain characteristics for both the synagogue and the Independence Palace. The results show that between 2002 and 2020, groundwater salinity at the synagogue site increased from 1.10 g/L to 3.39 g/L, accompanied by a 23% rise in soil permeability. At the Independence Palace site, salinity reached 2.01 g/L, with an 18% increase in permeability. Numerical simulations conducted using GEO5, PLAXIS 2D, and LIRA SAPR revealed consistent trends but varying magnitudes of subsidence. PLAXIS 2D predicted settlement values approximately 15–25% higher than GEO5, while LIRA SAPR produced estimates 10–20% lower. Among the models, GEO5 demonstrated the closest agreement with field observations. The Independence Palace underwent relatively rapid stabilisation due to an effective drainage system, with consolidation occurring over approximately 100–150 days. In contrast, the synagogue experienced prolonged settlement over a period of 10–15 years, driven by high groundwater saturation and river recharge. These findings confirm that hydrochemical evolution plays a critical role in governing soil permeability. Consequently, cross-validation using multiple modelling platforms is essential, and long-term settlement assessments in complex hydrogeological environments must account for time-dependent changes in permeability.