The estimation of main factors which exerts influence upon functioning reliability of system «tunnels – underground space» is executed. It is shown that hydrogeological conditions have a special importance for construction and maintenance of subway tunnels in Saint-Petersburg. The hydrodynamic effect of regional and local water-bearing horizons on development and activation of different processes such as groundwaters flow, quicksands, head water inrush, underground constructions deformation is analyzed. The influence of hydrochemical conditions on formation of underground space aggressiveness to constructional and waterproofing materials of the tunnels is established. The negative effect of underground microbiota activity on degradation of reinforced concrete and castiron tunnel lining is shown.
The natural and technogenic factors effect on exploitation reliability of subway tunnels located in Upper Vendian clays are analyzed. It is noted what the fractured clays has been studied during the exploring of the first metropolitan lines. It is emphasized what the intensity of clay fracturing increases in thalweg zones of paleo-valleys within the bounds of which the quantity of underground water leakages in tunnels increases. The hydrodynamic and hydrochemistry conditions of Vendian high head horizon (lied under clays) influence on deformation and destruction of tunnels lining are investigated. The reduction of clays shear strength parameters under the interaction of clays and liquid phases is experimentally studied. The water extracts chemical composition of disintegrated construction materials and sinter forms are resulted. The important role of biocorroion in constructional and waterproof materials (included bitumen) disintegration is shown. The protection methods of tunnels constructions from biocorrosion are recommended.
In this paper the features of subway construction materials degradation depending on engineering-geological, hydro-geological and geoecological conditions of Saint Petersburg underground space are considered. The basic types of subway construction placing and their destruction specificity depending on influence of water-bearing horizons hydrodynamic and hydro chemical conditions, natural and natural-technogenic gas bio-production and microbial activity are analyzed. The examples of the disintegrated materials and new growths (salt efflorescence, stalactites and others) chemical compound features depending on the content of ground waters basic components affecting on tunnels lining are resulted.
The main natural and anthropogenic factors determining the vitality of diverse microbiota in the underground space (US) of St. Petersburg are analyzed. The data on characteristic microbial flora of buried bogs, contributing to the growth of microorganisms in the underlying soils are given. The processes influencing the formation of reductive-oxidizing and acid-alkaline conditions and viability of various physiological groups of microorganisms in RS are considered. Peculiarities of destruction of foundation brickwork, reinforced concrete and cast-iron lining of some transportation tunnels are considered. A comparative assessment of the influence of water extracts selected from fractured building materials and new formations on the chemical composition of tunnel linings is given. The metabolism of various bacteria and microfungi leading to the destruction of building materials is characterized.
The Yakovlevsky deposit of the Kursk Magnetic Anomaly (KMA) is characterized with large reserves and high grades of iron ores which are products of chemical weathering of ferruginous quartzites in Pre-Paleozoic period. High-grade iron ores (HGIO) are non-compacted variations with high porosity and even macroporosity. Their occurrence depth is over 500 m. The article analyses granulometric composition, physical properties and strength parameters of various highgrade iron ore types. Acceptable level of hydrodynamic pressure is calculated with the view of the pillar width, which is equal to 53 m, and various widths of individual working spans. Forecast time of underground waters penetration from the overlying Low Carboniferous aquifer horizon to the - 370 m horizon is calculated. Conclusions are made on negative impact of underground waters penetration which leads to secondary watering of the high-grade iron ores, a sharp decrease in their durability that creates preconditions for inrush formation.
The engineering and geological conditions of the site of the projected Beregovaya compressor station are analyzed, with special attention paid to endogenous and exogenous geological processes and phenomena that will determine the safe operation of the station. The features of physical and mechanical properties of the flysch strata are considered, and the weakest and most water-resistant rock varieties - marl - are highlighted. It is shown that in marl sediments with their additional moistening the most probable formation of landslide sliding surfaces. Examples of possible measures for providing compressor station protection from dangerous geological processes are given.
