Construction and Geotechnics

The geology of St. Petersburg is represented with a heavy layer of weak structurally unstable soils. Using of vibro-extraction and vibro-driving of sheet piles in such conditions requires a particularly responsible approach in order to predict the emerging dynamic effects and the zones of their influence on the surrounding buildings and structures. Therefore, the task of looking for possible patterns describing these processes is highly relevant. For this purpose, the authors have updated the map of engineering-geological zoning according to Zavarzin with use of more than 50 reports of engineering-geological surveys. On this map the sensitive to the high-frequency vibrations soil layers are identified. Also, more than 70 reports on vibration monitoring of vibration driving and vibration extraction of sheet piles in St. Petersburg have been analyzed. The influence on the value of vibration acceleration of the following factors has been investigated: the geological features of the site, the distance to the source of vibrations, the characteristics of the vibrating hammer (operating frequency, driving force) and sheet pile (length, cross section), the location of measurements (on the ground or on a structural element of the building). The result of the work is the diagrams that clearly show the presence or absence of a relationship between the studied parameters. The absence of dependencies for some of the investigated parameters may be caused by the factors which influence cannot be predicted. These factors are the occurrence of large friction forces in the joints of sheet piles; the presence of lenses of dense soils or boulders during sheet piles driving; violations of the technological process. The zone of the influence of high-frequency dynamic impact was identified as 25 meters, which is in good agreement with the results of in-situ monitoring.

Anthropogenic and dynamic impacts on facilities of underground urban infrastructure increase at intensive development of megacities. The unique long-operating underground structures of sewage system require special protection against anthropogenic influence as their wear degree in difficult soil conditions reaches 70 % and more. Therefore, providing structural (mechanical) safety of underground structures of excessive level of danger and responsibility defines sustainable operation and future development of geotechnical infrastructure of the megacity in general. Long-term studying dynamics of changes of technical state of underground sewage structures of the megacity, long operating (for more than 70 years) in soft soils, allowed establishing regularities of influence of intensive anthropogenic and dynamic impacts on this process. For the first time, based on developed continuous models of defective structures potentially dangerous sections have been identified, they are subjected to manifestation of critical failures; ways of their correction are presented. Numerical simulation has defined borders of defectless joint operation of the system “target area - geomassif - underground structure". Scientific substantiation of boundaries of areas with potentially dangerous sections of underground sewage facilities with account of external anthropogenic and dynamic impacts constitutes the basis for elaborating regulations on safe development of geotechnical infrastructure of the historical area of St. Petersburg. The proposed methods of monitoring and protection of geotechnical infrastructure have been successfully used for many years by St. Petersburg Vodokanal in areas of influence of anthropogenic factors and objects under construction on underground structures, they ensure an optimal combination of sustainable operation and development of geotechnical infrastructures of megacities.

The results of computer modeling of the process of formation and development of areas of plastic deformations in the connected base of a double-slit ribbon foundation are presented. All calculations are performed using computer programs developed with the participation of the author. These programs allow you to take into account all the variety of physical and mechanical properties of the foundation soil (volume weight, internal friction angle, specific adhesion, lateral pressure coefficient and deformation modulus) and the foundation material (elastic modulus and Poisson's ratio). In the calculations, it is assumed that the value of the lateral pressure coefficient of the soil is 0.75, as is typical for cohesive clay soils, and the same value for the foundation material is assumed to be 0.43 (converted through the Poisson's ratio). Based on the results of calculations, it was possible to determine the features of the stress state of the base of the double-slit foundation and the process of development of plastic areas in the core of the foundation. First of all, the part of the bearing capacity of the base of the double-slit foundation that contacts its side surface is realized, and the inclusion of the side surface of the slit foundation in the work occurs from the bottom up. Then the part of the base that is located directly under the soles of the walls in the ground (cracks) is included in the work. It is established that the smaller the distance between the slits, the greater the bearing capacity of the base and the greater its part falls on the side surface. The bearing capacity of the base of a double-slit foundation is directly proportional to the depth of its foundation (the height of the cracks). The part of the load-bearing capacity realized on the side surface of the foundation can reach 60 % or more of its full value. An engineering method for calculating the load-bearing capacity of the base of a double-slit foundation, including simple formulas and graphs, is proposed. The method is formalized in a calculator program. The verification calculations showed a high degree of accuracy in approximating the results of the numerical experiment.

Import substitution in the industry of water supply and sanitation (WSS) in the context of the current economic crisis is a rather attractive operation. The problem of import substitution in the water supply and sanitation industry is complex being characterized by features such as production conditions, the availability of scientific and technical developments, the intensity of relations with foreign colleagues. Many WSS sector participants focus on implementing measures to reduce their dependence on foreign suppliers and shifting to products of domestic manufacturers within the framework of import substitution. The overall goal of this paper is to assess the feasibility of import substitution in the sector of water supply and sanitation in Russia. In addition, the article offers a choice of equipment in the field of water treatment, which can be produced in Russia in order to create products that are competitive on the world market. This article provides a review and analysis of the nomenclature of the main and auxiliary equipment for the water supply sector. The article offers an overview of patents for useful models in the field of water treatment which are feasible to produce in the domestic industrial market, however, they are currently imported from abroad. The review investigates the extent of import substitution demanded by the industry of water supply and sanitation in Russia. It also describes types of water treatment equipment to be produced in Russia. The structure of the paper is as follows: - the history of the development of water supply and sanitation industry; - the analysis of the current status of water supply and sanitation industry of Russia and review of basic technological equipment for natural water treatment plants and for wastewater treatment; - the review of utility model patents in the field of water treatment; - the conclusion.