To the question of conditions, factors and criteria of geodynamic risk in the boundaries of urban areas

Abstract

Formulation of the problem Loess deposits are widespread. They are characterized by the singular difficult deformations, therefore, their structure collapses. We have shown in the previous researches that in a zone of influence of the city properties of rocks change over time. Physical condition and gradation of microaggregates change over time as well. As a result, complex changes of physical properties occur. The duration of moistening affects the type and magnitude of the changes. Microaggregates do not disintegrate when the duration of moisture is short. When the duration of moisture is long, disintegration of the microaggregates is accompanied by the re-packaging and increasing of the endurance.

The purpose of the article. The forecast of relative subsidence values and endurance can be performed using statistical analysis and group accounting method arguments. In this paper, we show the possibilities of forecasting using the example of a concrete construction site.

Methods. Statistical method and the method of inductive modeling by group accounting of arguments were used in prognostic researches. In calculation of subsidence in the zone influences and stability analyses we used standard methods.

Results. The object of research is an elementary natural and technical system formed by a projected building. The house will be built in the zone of distribution of loess’s (the erosion basin Vstrechnaya, Dnipro). The groundwater level in erosion basin is at a depth of 0.5 to 14.0 m. The magnitude of the increase of Groundwater level is 1.55 m from the modeling results in the research area. According to the results of multi-year data statistical analysis, close correlation relations between the property indices, regression between indicators of the physical state was found. The forecast values of mechanical properties' indicators are established as the results of inductive modeling with the method of group accounting of arguments. The forecast values of humidity and other indicators of the physical state, the content of individual fractions were set as well. The values were calculated to characterize a moderate and intensive change in soil properties in comparison with the natural state. Deformation calculations in the ground base and stability analysis were performed by standard analytical methods.

Scientific novelty and practical significance. The following variants of events were considered: long-term or short-term humidification, complete or selective change in indicators of the physical condition of soils and microaggregate structure. The loss of strength is most likely to happen in case of emergency soaking of soils when the physical state changes but dispersion do not change.