The article describes the features of geomorphological and geological-structural construction, engineering-geological and hydrogeological conditions of Primorskiy part of Saint Petersburg. There are describe a geological section of rocks of the Quaternary, given hydrochemical characteristic for typification and zoning of development areas of construction.
The new situation with the carrying out of monitoring of underground waters on regional level was mainly caused by two reasons: 1) new regulations on the preservation of the environment were approved; the present water Regulations are being renewed; 2) studying of regime-forming factors of underground waters (geological, cosmic, climatic, biological, hydrological and technogenic) testify to the urgent necessity of introducing certain amendments into the system and maintainance of monitoring of underground waters.
The new innovative program of the Saint-Petersburg State Mining Institute provides the organization of all-the-year-round operating range in Kavgolovo of the Leningrad region. There are new buildings for training and residing of students will be construct. Hydrogeology and engineering geology department of Mining Institute together with the prospecting organization «SU-299» were carried out the researchers for the construction of the buildings. The archival and literature data, results of the researches of engineering-geological conditions and a hydrogeological structure of Kavgolovo range were analyzed. The parameters of mechanical-and-physic properties of sandy-argillaceous rocks of the buildings rafts were obtained. The materials will be used during the field training with students of a specialty «Underground waters exploration and engineering-geological researches».
In the concept of development of St.-Petersburg the important role plays the improvement of the general scheme of the water drain of city, including reconstruction of old and construction of new underground sewer collectors. Because of diversity and complexity of engineering-geological and hydro-geological conditions of St.-Petersburg the building of such underground constructions represents the certain difficulties. The brief review of a current condition of a sewer network of St.-Petersburg is given. Features of engineering-geological and hydro-geological conditions of construction of underground sewer collectors by microtonneling technique in different areas of city are shown. The basic provisions on studying conditions of construction and operation of the given constructions are formulated.
Statistical data on the reasons of buildings and structures transition to emergency and pre-emergency state are analyzed. In more than 60 % of cases the loss of stability of structures is observed as a result of activation of various factors acting during operation of buildings. The results of experimental studies showing the negative transformation of sand-clay soils under the influence of sewage runoff and the activation of microbial activity are presented. Empirical dependencies of changes in the coefficient of filtration of sands and strength of clayey soils when the bacterial mass increases are given. The role of organic pollutants in changing the redox conditions in the city underground space has been analyzed. The recommendation of the necessity to take into account the technology of industrial production in the practice of engineering surveys is given.
Natural and technogenic factors determining the evolution and destabilization of the geo-ecological state of the underground space of St. Petersburg are analyzed. Special attention is paid to buried marshes, drainage network and groundwater pollution as the least stable parts of the underground space. The main pollutants of the city are sewage and buried wastes, which bring not only a large amount of organic substances easily assimilated by microorganisms, but also additional microflora. Since the mid-20th century, petroleum hydrocarbons are considered to be active pollutants in the underground space. Large amounts of organic matter in the underground space leads to the formation of a reducing environment and microbiological activation. Conducted mass sampling of redox potential, determining the features of the chemical composition of groundwater, as well as assessing the bacterial mass in sandy clay sediments of the section indicate the importance of physico-chemical and biochemical processes in the evolution and destabilization of the underground space of the city. As a result of these processes, negative transformation of dispersed soils, leading to the formation of floats, the active development of gas-dynamic phenomena, and a high level of environmental aggressiveness are observed. A special form of corrosion of building materials caused by the activity of microorganisms (bio-corrosion), which enhances chemical, electrochemical and other types of underground exposure, has been analyzed. It was found that more than 50 percent of the total destruction of underground pipelines, foundations, and basement walls is the result of bio-corrosion.
Проанализированы природные и техногенные факторы формирования окислительно-восстановительных условий в обводненной толще дисперсных пород. Показано влияние восстановительной обстановки и активности микробиологической деятельности на изменение состава и физико-механических свойств песчано-глинистых отложений. Приведены примеры трансформации пород при загрязне нии грунтовых вод и пород органическими компонентами.