Authors

Gulyaev Alexander N., Osipova Anastasia Yu.
SEISMICITY IN THE MIDDLE URALS AND BUILDING IN THE REGION

Architecton: Proceedings of Higher Education №2 (42) June, 2013

The article provides a characteristic of seismicity in the central part of the Ural region and its impact on engineering structures for the purpose of contribution to the seismic safety of engineering structure, both built and planned for building or reconstruction.

Data gathering and processing have been carried out concerning the seismicity of the central part of the Ural region, maps of observed tremor magnitudes during 1788-2010 have been compiled, and analysis of spatial location of the epicentres of notable earthquakes (a score of 3-4 by the MSK-4 scale and over), as well as distributions of earthquake magnitudes and intensities in time have been estimated. These data have been used to estimate the seismic potential of the earth crust in the central part of the Ural region, the seismotectonic conditions and the nature of the centres of the strongest earthquakes. Detailed seismic zoning of the central part of the Ural region has been carried out.

It has been established that the Middle Urals is the most seismic area of the latest Ural mountain belt. It has the greatest part of epicentres of notable earthquakes.

Generally, the seismic engineering conditions of the Middle Urals are estimated as favourable and safe for the majority of engineering projects. This is due to the low seismic and tectonic activity of the earth crust in the Middle Urals and favourable seismic conditions for the grounds of the region. Anti-seismic action in the central part of the Ural region is important only for designing and building particularly critical projects in respect of seismic safety – mainly high-rise buildings of 40 and more storeys, and other critical projects.

Gulyaev Alexander N., Osipova Anastasia Yu.
ADVERSE FACTORS IN THE ACTIVE LAYER OF THE EARTH CRUST AFFECTING THE CIVIL ENGINEERING STRUCTURES OF EKATERINBURG

Architecton: Proceedings of Higher Education №2 (38) June, 2012

In the city of Ekaterinburg, buried utility lines, most of the foundations and road and railway and tramway beds are located in the so-called «active layer» of the earth’s crust, i.e. in the top 2.5-3.0 m. The active layer of the earth’s crust is associated with the boundary zone between the atmosphere and the lithosphere, consists of non-uniform ground in terms of composition and physical and mechanical properties and is sensitive to external effects from the atmosphere, lunar and solar tides, technogenic events and to internal tectonic and hydro-geological processes in the earth’s crust. The results of such sensitivity are movements of ground and rock and seasonal and other slower changes in their physical and mechanical properties. These precipitate failures of buried lines and cause damage to the foundations and walls of land structures, and accelerated wear of road surfaces. A number of measures are proposed to mitigate the impact of the crustal active layer on civil engineering structures.

Gulyaev Alexander N., Osipova Anastasia Yu.
ZONING OF NIZHNY-TAGIL CITY TERRITORY IN SVERDLOVSK OBLAST BY ESTIMATED SEISMIC IMPACT

Architecton: Proceedings of Higher Education №1 (37) March, 2012

Schematic zoning by estimated seismic impact has been performed for the territory of the city of Nizhni Tagil, most of which is represented by residuum mantle rocks classified as Category 2 in terms of their seismic properties according to SNiP II-7-81* code. The seismic impact is estimated at 6 points by the MSK-64 scale for standard (mass construction) buildings and critical structures, and at 7 points for especially critical structures.

In the peripheral part of the city with predominantly Category 1 rocks in terms of their seismic properties according to SNiP II-7-81** code, this impact is estimated at 5 points by the MSK -64 scale for standard (mass construction) buildings and critical structures and at 6 points for especially critical structures.

In small-size sites in the river flood plain and in the boggy tectonic denudation depressions, which feature the most adverse rocks of Category 3 in terms of seismic engineering properties, the impact is estimated at 7 points for standard (mass construction) buildings and critical structures and 8 points for especially critical structures. Typically, adverse rocks are removed from the foundation of a structure to be built and are replaced, where necessary, with more suited coarse technogenic rocks.

Generally, the seismic engineering conditions in the territory of Nizhni Tagil are favourable and safe for the majority of civil engineering structures. An exception is areas that have been rendered weak by underground mine workings, where there is a risk of caving.

Gulyaev Alexander N., Osipova Anastasia Yu., Shchapov Vladislav A.
NONUNIFORMITY OF SOILS IN THE FOUNDATION BED AS THE PRINCIPAL CAUSE OF DAMAGE TO BUILDINGS IN EKATERINBURG

Architecton: Proceedings of Higher Education №4 (36) December, 2011

The upper part of the earth crust in the Middle Urals has a complex structure. It consists of non-uniform soil in terms of structure, genesis and physical and mechanical properties. These soils are mainly represented by Palaeozoic volcanogenic sedimentary soils, containing intrusive magmatic matter of different structure. The consolidated bed-rocks are broken by zones of strain, and in their upper part, they were turned by weathering processes during the mezozoic-kainozoic time into relatively less consolidated eluvial soils coats of various structures, physical and mechanical properties and thickness. Deep weathering voids are abundant in relict Palaeozoic zones of strain of the earth crust. In some of them, where active circulation of underground waters occurs, suffusion processes occur, and pseudo-karst phenomena are observed, and in carbonate soils karst phenomena are present. The heterogeneity of the geological tectonic structure of the upper part of the earth crust in the Middle Urals in combination with severe climate present the main adverse factor causing deformations and damage to the engineering structures due to their uneven settlement.

An example is the nine-storied residential building No. 6 in Musorgsky Street in Ekaterinburg, which had to be evacuated in an emergency. The results of the geophysical studies carried out in 2010 suggest the presence of zones of strain in the upper part of the earth crust under this building in which rocks possess reduced strength allow active circulation of underground waters through them. Abnormal settlement took place over these zones, which resulted in deformation and damage to the building.

This could have been avoided, had engineering geological explorations been performed on the construction site back in 1979.

Gulyaev Alexander N., Osipova Anastasia Yu.
SEISMICITY AND SEISMIC ZONING OF EKATERINBURG AND ADJACENT POTENTIAL DEVELOPMENT AREAS

Architecton: Proceedings of Higher Education №3 (35) September, 2011

Based on the results of General Seismic Zoning of the Russian Federation (OSR-97), the Middle Urals have been classified into the class of areas where seismic activity is to be taken into account in building design and construction. Ekaterinburg and its adjacent prospective development areas are located within potentially seismic zones. This has made it necessary to do a detailed zoning of this territory based on estimated seismic impact. This study is based on analysis of data on a) the structure of the upper part of the earth crust; b) physical and mechanical properties of soils and rocks; c) baseline seismic impact on civil engineering objects of different degree of criticality in respect of seismic safety (according to OSR-97).

The results of the study suggest that the seismic conditions in Ekaterinburg and adjacent potential development areas are favourable and safe for the majority of civil engineering objects owing to the following factors: low seismic activity of the earth crust in the Middle Urals (perceptible earthquakes are seldom and their intensity is insignificant, from 3-4 to 6.0-6.5 by the MSK-64 scale); b) favourable seismic conditions in terms of geology (the territory under consideration has mostly Palaeozoic bedrock covered with a relatively thin layer of residual soil and Quaternary sediments). Antiseismic safeguards within the territory considered are reasonable only in relation to the design and construction of high-rise buildings higher than 40 stories and of environmentally hazardous industrial facilities.

Geologically, the most adverse factor for civil engineering objects within this territory is the one that may be conditionally called geodynamic. It manifests itself in the form of variations over time in horizontal and vertical distances of the earth surface as revealed by GPS monitoring. These variations are, presumably, caused by seasonal variations in the temperature of the soils and rocks in the active layer (the top 7-10 metres of the earth crust) and, probably, by other global seasonal processes. Unlike perceptible earthquakes, the geodynamic factor operates continuously and is likely to be causing accidents in buried lines, accelerated wear of the road surfacing and, in some cases, damage to building foundations and walls.

The tectonic activity of the earth crust in the territory under consideration has been low during recent history and presently. No zones of deformation of the earth crust that may be classified as «an active fault» have been revealed in this territory.