Risks of the soil foundations stability losses of the Kyiv-Pechersk Lavra Dormition Cathedral due to the urban activities

Abstract In the research, the use of numerical analysis of the soil foundations stability losses of Dormition Cathedral, where in the interiors of the II tier northern part, deformations of structural elements have been recorded since 2016, probably caused by uneven settlement of the foundations due to overmoistening. The initial data were the results of constant monitoring of the technical condition of the building, engineering and geological investigations, etc. To determine (confirm) the deformation factors and forecast their activation stabilization, a numerical calculation of the stress-deformation state of the cathedral soil foundations was performed for soils in their natural state and water-saturated state. The calculations of the stress-strain state of the cathedral foundations and the determination of plastic deformation zones were done using the PLAXIS software complex. They showed an increase in deformations in its northeastern part, under the basement premises, in particular for the scenario of flooding of the underground part. According to calculations, the plastic deformations of the base soil and, as a result, the deformations of structural elements are still in the stage of incomplete stabilization in the northern part of the cathedral, in the area where the basement part is located. The deformations extend the entire pile field under the construction of the cathedral, but do not reach the extreme minimum values in 8 cm. The main factor in the activation of deformations is the overmoistening of the soil massif, the impact of blast waves is not excluded (confirmation of which requires vibration monitoring). The direction of improving protection management measures for Dormition Cathedral is proposed.