GEODYNAMICS

Abstract

Purpose. The paper substantiates the need for building seismic zoning maps of Kyiv in the physical parameters of ground motions: peak ground accelerations (PGA), peak ground velocities (PGV) or peak ground displacements (PGD), which are the basis for the effective use of methods for calculating seismic loads on buildings, structures and individual responsible constructions. An intermediate stage in the creation of such maps is the development of a map of seismic zoning of the territory of Kyiv in terms of relative integral estimates of spectral increments in seismic soil oscillations, arising from the influence of the peculiarities of the distribution of physical parameters of soils. The intermediate map gives the distribution over the city territory of a quantitative assessment of the influence of the spectral characteristics of the soil on the seismic hazard, expressed in systemic physical quantities. Methodology. An analytical-empirical approach to mapping the seismic hazard of territories is applied. Within the territory of Kyiv, using the method of seismic-geological analogies, areas (taxonomic zones) were identified, where the seismic effect can differ significantly both in physical parameters: displacement, speed, acceleration – and the ability of soil strata to significantly affect the spectral characteristics of the soil. Results. For each taxonomic zone, a computational seismic-geological model with inelastic deformation parameters has been built, which makes it possible to take into account the occurrence of nonlinear effects under significant seismic influences. Equivalent linear modeling was used to calculate the frequency response of seismic-geological soil models for each taxonomic zone. The averaged frequency response for the ground conditions of the territory of Kyiv was calculated. A map of the distribution of the deviation of the integral amplification of seismic oscillations from the average value for the territory of Kyiv was built. The integral spectral amplification is the area of the subspectral function. A dynamic analysis of the propagation of seismic oscillations in seismic-geological models is carried out and the influence of the upper sedimentary layer on the value of the peak ground acceleration PGA on the free surface is illustrated. Originality. For the first time within the territory of Kyiv, areas (taxonomic zones) have been identified, where the response of the soil to the seismic effect will differ. A map of the distribution of the deviation of the integral amplification of seismic oscillations by soils from the average value for the territory of Kyiv was constructed. Practical significance. The map of seismic zoning of Kyiv in amplitude terms of soil oscillations is proposed to be used when applying the spectral method for calculating an emergency combination of loads, taking into account seismic effects, to determine the value of the calculated relative ground accelerations of the construction site under study.