Long-term stability of old cathedrals in St. Petersburg

摘要

A number of historic cathedrals in Saint Petersburg, such as Peter and Paul Cathedral, Kazan Cathedral and St. Isaac’s Cathedral, experience progressive foundation failure alongside long-term and differential settlements leading to development of cracks in their bearing structures. Similar adverse conditions of these edifices is currently related to the natural conditions of Saint Petersburg’s historic centre and negative transformations of underground space components: soils, groundwater, microorganisms, gases and materials contributed from subsurface structures and services. The generalities of Cathedrals location and its bases are typical geotechnical section of Low terrace, development of swamps, peaty soils, quick sands and water and gas saturated weak soils and fissured bed clays (hard soils). The high degree of groundwater contamination with organic and inorganic pollutants generates active development of marsh and alien biocenoses. The authors propose a concept and structure of a complex programme of preventive geotechnical and geoenvironmental monitoring for cathedrals.