There are microorganisms in soils and their activity can have a positive or negative impact on soil properties and groundwater. The positive effect of microorganisms includes the self-purification and self-regulation of contaminated groundwater and soil. The negative effect on soil is the change in grain-size composition; the weakening of engineering properties of soils; and the development processes, such as biogas generation, microbial quick-sand formation, and soil liquefaction. This paper addresses the negative effects of microbial activity on soil. Research on the impact of microbial activity in an underground space has been motivated by observations associated with underground infrastructure, such as subway tunnels, utilities tunnels, deep mines including those with tailings, and infrastructure with shallow and deep foundations. An overview of microorganisms in soil and an analysis of microbial activity in soils under the influence of natural and human-made factors are presented. Field and laboratory experiments show the significant impact of microbial activity on the engineering properties and consistency of the soil. Due to the complexity of the process, a study of microbial activity in the soil profile requires an integration of microbiology, biochemistry, engineering geology, and geotechnical engineering knowledge and experience.

The article reviews the issues concerned with correctness of the engineering-geological and hydrogeological assessment of the Upper Kotlin clays, which serve as the foundation or host medium for facilities of various applications. It is claimed that the Upper Kotlin clays should be regarded as a fissured-block medium and, consequently, their assessment as an absolutely impermeablestratum should be totally excluded. Presence of a high-pressure Vendian aquifer in the lower part of the geological profile of the Vendian sediments causes inflow of these saline waters through the fissured clay strata, which promotes upheaval of tunnels as well as corrosion of their lining. The nature of the corrosion processes is defined not only by the chemical composition and physical and chemical features of these waters, but also by the biochemical factor, i.e. the availability of a rich microbial community. For the first time ever, the effect of saline water inflow into the Vendian complex on negative transformation of the clay blocks was studied. Experimental results revealed a decrease in the clay shear resistance caused by transformation of the structural bonds and microbial activity with the clay’s physical state being unchanged. Typification of the Upper Kotlin clay section has been performed for the region of Saint Petersburg in terms of the complexity of surface and underground building conditions. Fissuring of the bedclays, the possibility of confined groundwater inflow through the fissured strata and the consequent reduction of the block strength as well as the active corrosion of underground load-bearing structures must be taken into account in designing unique and typical surface and underground facilities and have to be incorporated into the normative documents.

Urban subsurface space is considered to be a dynamic multicomponent system, which includes sandy-clayey soils, groundwater in different state, microbiota, gases, and underground facilities (either as...

The underground space of the Kupol deposit is analyzed as a multicomponent system – rocks, underground water, microbiota, gases (including the mine atmosphere) and supporting structures – metal support and shotcrete (as an additional type of barring) and also stowing materials. The complex of host rocks is highly disintegrated due to active tectonic and volcanic activity in the Cretaceous period. The thickness of sub-permafrost reaches 250-300 m. In 2014, they were found to contain cryopegs with abnormal mineralization and pH, which led to the destruction of metal supports and the caving formation. The underground waters of the sub-permafrost aquifer are chemically chloride-sulfate sodium-calcium with a mineralization of 3-5 g/dm3. According to microbiological analysis, they contain anaerobic and aerobic forms of microorganisms, including micromycetes, bacteria and actinomycetes. The activity of microorganisms is accompanied by the generation of hydrogen sulfide and carbon dioxide. The main types of corrosion – chemical (sulfate and carbon dioxide), electrochemical and biocorrosion are considered. The most hazardous is the biocorrosion associated with the active functioning of the microbiota. Forecasting and systematization of mining and geological processes are carried out taking into account the presence of two zones in depth – sub-permafrost and below the bottom of the sub-permafrost, where mining operations are currently underdone. The importance of assessing the underground space as a multicomponent environment in predicting mining and geological processes is shown, which can serve as the basis for creating and developing specialized monitoring complex in difficult engineering and geological conditions of the deposit under consideration. Подземное пространство месторождения Купол анализируется как многокомпонентная система – горные породы, подземные воды, микробиота, газы (в том числе рудничная атмосфера) и несущие конструкции – металлическая крепь и торкрет-бетон (в качестве дополнительного вида крепления), а также закладочные материалы. Комплекс вмещающих пород имеет высокую дезинтегрированность за счет активной тектонической и вулканической деятельности в меловом периоде. Мощность многолетнемерзлых пород достигает 250-300 м. В 2014 г. в них было установлено наличие криопэгов с аномальной минерализацией и pH, что привело к разрушению металлических крепей и образованию вывалов. Подземные воды подмерзлотного водоносного горизонта по химическому составу хлоридно-сульфатные натриево-кальциевые с минерализацией 3-5 г/дм3. Согласно микробиологическому анализу в них присутствуют анаэробные и аэробные формы микроорганизмов, в том числе микромицеты, бактерии и актиномицеты. Деятельность микроорганизмов сопровождается генерацией сероводорода и диоксида углерода. Рассмотрены основные виды коррозии – химическая (сульфатная и углекислотная), электрохимическая и биокоррозия. К наиболее опасной относится биокоррозия, связанная с активной деятельностью микробиоты. Прогнозирование и систематизация горно-геологических процессов выполнены с учетом наличия двух зон по глубине – многолетнемерзлых пород и ниже подошвы мерзлоты, где в настоящее время ведутся горные работы. Показана важность оценки подземного пространства как многокомпонентной среды при прогнозировании горно-геологических процессов, что может служить основой создания и развития комплексного специализированного мониторинга в сложных инженерно-геологических условиях рассматриваемого месторождения.

Sapropel is natural organic material, which is used in many industries, such as agriculture, medicine, pharmaceutical, manufacture of energy carriers and building materials. However, the widespread use of sapropel is associated with its high hydrophilicity and moisture capacity, leading to technological difficulties with sapropel dehydration to required humidity, depending on its further application. The article discusses various aspects sapropel beneficial application, primarily the advantages of the use of sapropel as a fertilizer for cultivated areas, and for the reclamation of industri-al wastelands and mined lands. As a part of this study, experimental research of the qualitative and quantitative parameters of sapropel of Savelievskoye field of the Yaroslavl region was conducted. Based on the results of this research, the nature of the high hydrophilicity of sapropel of Savelievskoye field and the possibilities of reducing its humidity for the production of fertilizers is revealed.

The article analyzes the causes of the development of deformations in historical buildings in St. Petersburg. Emergency buildings in Telezhnaya street are considered. The accumulated settlement difference of the buildings is up to 35 cm, which corresponds to relative nonuniformity of 0.01. As a result of the research, abnormally complex engineering-geological and hydrogeological conditions were identified due to the widespread development of boggy deposits (peat), as well as contamination of soils and groundwater. This led to the transition of lake-sea sands to the state of a sand flow, and clayey soils to quasi-plastic differences characterized by low internal friction angles and a small adhesion value. Using numerical calculations of the interaction of the buildings and the base, a cause-effect relationship has been established between the development of defects in brick masonry and settlements of buildings. The development of the settlement of the buildings is due to the fact that the foundations are located on the layer of sand, underlain by weak loams, whose properties degrade during contamination of the underground environment. In addition, some foundations of the surveyed buildings rest on a layer of peat or on rotten wooden piles or groundsills. The emergency condition of the buildings as a whole is explained by the development of the process of loss of stability of the foundations, rotting of piles or deformation of peat.