Technological solutions for strengthening the foundations of cultural heritage sites while preserving authentic material and minimizing intervention in load-bearing structures and the soil mass

Abstract

The paper examines technological approaches to strengthening the foundations of cultural heritage sites under conditions of dense urban development and a variable hydrogeological regime, with priority given to preserving authentic material and minimizing intervention in load-bearing structures and the soil mass. The results of comprehensive surveys and monitoring of historical buildings of the 18th–early 20th centuries with strip foundations made of rubble stone and brick masonry are summarized, supplemented by numerical modeling of the nonlinear behavior of the foundation soil accounting for masonry defects and staged construction. Jet grouting, sleeve injection, drilled-injection micropiles, and combined solutions are compared according to criteria including changes in deformation characteristics of the foundation soil, differential settlements, redistribution of contact stresses, and technological risks. It is shown that increasing the volume of ground improvement does not ensure a proportional increase in stiffness and may raise the likelihood of damage to historical masonry due to heterogeneity of the formed elements, excessive injection pressure, and changes in the seepage regime. A tendency toward a reduction in peak stresses in critical foundation zones is identified when strengthening parameters are properly selected; at the same time, rigid elements provide predictable limitation of settlements but require vibration control, whereas low-impact injections are characterized by lower technological impact with a more moderate increase in stiffness. The feasibility of an integral assessment of effectiveness combining mechanical reliability and an intervention index is substantiated, as well as a transition to probabilistic justification and adaptive management of works based on monitoring.