Application of modern soil models for numerical calculations of tank bases and foundations

Уже в ближайшем будущем от использования современных численных методов расчета будет зависеть прогресс в области проектирования оснований и фундаментов зданий и сооружений, поскольку возможности по совершенствованию строительных норм практически исчерпаны. Целью статьи является демонстрация возможностей численных расчетов с использованием современных моделей грунта на примере проектирования фундамента стандартного нефтяного резервуара для хранения нефти и нефтепродуктов. Приведено сравнение результатов расчетов осадки основания резервуара емкостью 30 000 м, выполненных в соответствии с действующими нормами проектирования и методом конечных элементов с применением программного комплекса PLAXIS. В частности, проведены численные расчеты с использованием современных моделей грунта: 1) модели грунта с упрочнением (Hardening Soil model, HS); 2) модели грунта с упрочнением и учетом малых деформаций (Hardening Soil small strain model, HSs). Показано, что использование указанных моделей при наличии требуемого объема исходных данных позволяет существенно уточнить вычисления, выполняемые по нормативным методикам. С учетом полученных результатов определена возможность оптимизации проектных решений при выборе типа фундамента резервуара. In the near future, the progress in design of bases and foundations of buildings and structures will depend on the use of modern numerical calculation methods since the opportunities to improve the building regulations are almost exhausted. This article aims to demonstrate the capabilities of numerical calculations with the use of modern soil models on the example of designing the foundation of a standard oil storage tank for crude oil and petroleum products. This article provides a comparison of the results of the base settlement of a 30,000 m tank calculations made in accordance with the current standards of design and the finite elements method with the use of the PLAXIS software package. In particular, the following numerical calculations with the use of modern soil models have been performed: 1) Hardening Soil model, HS; 2) Hardening Soil small strain model, HSs. It is shown that the use of these models in the presence of the required amount of baseline data can significantly refine the calculations performed according to normative methods. Considering the obtained results, the possibility of optimizing design solutions when selecting the type of foundation of a tank was determined.

Metallic and glass spherules in the loose deposits of the Put river head (Middle Urals)

Research subject. The article examines exotic mineral formations - spherules (balls) of various composition and structure, found in the Neogene sediments of the interfluve of the Put-Bisert rivers within the eastern wing of the Yurizan-Sylva de-pression.Materials and methods. The work was carried out using the authors' research results, the available data on similar formations both from the modern soil-vegetation layer, including peat and technogenic formations, and from more ancient Phanerozoic sedimentary, magmatic and ore complexes. The article uses the results of studies obtained by a scanning electron microscope “EVO MA 15” from ZEISS with an energy-dispersive attachment EDS “X-MAX 80” at the JSC “Mekhanobr” analytical laboratory.Results. A detailed study of the surface morphology, dimensions, chemical and mineral composition of three types of spherules - magnetite, iron-chromium composition and barium and titanium oxide, similar to the stoichiometric formula of sanbornite - was carried out. The surface of the balls of the second type is heterogeneous in structure and contains growths, some of which have the form of a flat, flattened, square, skeletal crystal of a sectorial structure. The inner surface of the crystal has a fine-mesh structure. The cells have a complex, elongated structure. At the periphery of the crystal, the cells transform into hollow channels, indicating growth from the gas phase. In composition, the sectoral crystal corresponds to a solid solution between magnesio-chromite and herzenite with an admixture of nickel, calcium and silicon. The internal microstructure of iron-chromium spherules has a myrmekite, two-phase structure.Conclusions. The obtained data indicate that such heterogeneous formations can be formed only in specific deep fluid-saturated high-temperature magmatic systems and delivered to the surface by hydrothermal fluids along weakened tectonic zones. The detection of these formations in the overlying sediments of the western wing of the Artinskaya anticline may indicate the proximity of large fluid-supplying deep structures that control the Bukharovskoye gas show.

Traces types in the deposits: case study of V–II millennium BC sites in the far northeast of Europe

The author publishes data on the main types of traces of human activity, revealed in the deposits of the sites with sub-terrain dwellings of the Neolithic and Eneolithic, modern territories of the Komi Republic and the eastern part of the Arkhangelsk Region. The description, expertise, analysis and interpretation of such evidences are an argumentative basis for further reconstruction of specific archaeological situations. The sequence of their development project creation use abandonment taphonomy determined the range of methods; the involved facts and the structure of the study. The author uses planigraphic and stratigraphic observations collected by researchers in the region; geomorphology; pedology; chemical and mineral composition of soils. These methods made it possible to determine the creation and the appearance of traces, as well as to identify problematic situations for which the data are still insufficient. The sediments are classified into four groups: original soil; sediments modified by mechanical and geochemical influences; and soils formed after the abandonment of the sites, including modern soil. As a result, it is determined that for research in archaeology, the entire complex of deposits, including modern soil, is of significance as evidences. The author therefore proposes to go beyond universal definitions of cultural layer, cultural or culture-bearing deposits, and to study and describe specific contexts of traces and remains under research. The available experience is predominantly the results of purely archaeological research with occasional use of science data. It is obvious that the traces of prehistoric life were created under complex conditions with the influence of physical, chemical and biological processes. Therefore, to further accumulate the evidence base of archaeological research, experiments in systematic comprehensive analysis of deposits of sites, buried in the ground are necessary.

Comparison of the results of numerical calculations using modern soil models (Hardening Soil, Hardening Soil Small and Generalized Hardening Soil) with the geotechnical monitoring results

The use of modern soil models is impossible without carrying out a full range of laboratory tests required to determine the initial soil parameters and their further verification. The correctness of these aspects has a significant impact on the final result of numerical modeling. This paper gives a brief overview of the investigated soil models, presents the results of their verification using the geology of St. Petersburg, and compares the results of their verification on the example of the geology of St. Petersburg. Furthermore, the calculation results are compared using verified soil models (Hardening Soil, Hardening Soil Small and Generalized Hardening Soil) and unverified soil models (Hardening Soil) with geotechnical monitoring data. As an example, the authors describe a method intended for modeling the upheaval of the base of buildings of the surrounding development when using Fundex bored piles on an adjacent site.