ABSTRACT
The article analyzes the causes of the development of deformations in historical buildings in St. Petersburg. Emergency buildings in Telezhnaya street are considered. The accumulated settlement difference of the buildings is up to 35 cm, which corresponds to relative nonuniformity of 0.01. As a result of the research, abnormally complex engineering-geological and hydrogeological conditions were identified due to the widespread development of boggy deposits (peat), as well as contamination of soils and groundwater. This led to the transition of lake-sea sands to the state of a sand flow, and clayey soils to quasi-plastic differences characterized by low internal friction angles and a small adhesion value. Using numerical calculations of the interaction of the buildings and the base, a cause-effect relationship has been established between the development of defects in brick masonry and settlements of buildings. The development of the settlement of the buildings is due to the fact that the foundations are located on the layer of sand, underlain by weak loams, whose properties degrade during contamination of the underground environment. In addition, some foundations of the surveyed buildings rest on a layer of peat or on rotten wooden piles or groundsills. The emergency condition of the buildings as a whole is explained by the development of the process of loss of stability of the foundations, rotting of piles or deformation of peat.
