Construction of deep pits leads to changes in the stress-strain state of the soil mass within the radius of the zone of influence. This is caused by base unloading during excavation, horizontal displacement of excavation walls, technological factors. When falling within the zone of existing development, there is a need to assess and geotechnically predict the behavior of the foundations of existing buildings and structures. Existing and newly emerged Известия КГАСУ, 2021, № 4 (58) Основания и фундаменты, подземные сооружения 13 defects and damages of soils must be taken into account. The aim of the study is to determine the dependences of the main deformation characteristics of clay soil with existing defects on the basis of laboratory studies, for this purpose it is necessary to: conduct an experimental study in triaxial compression of clay samples with cracks and without cracks; establish the peculiarities of crack development in the clay sample structure; to establish the peculiarities of deformation development of cracked clay soil under triaxial compression.

In reinforced concrete structures under cyclic loads one of the types of failure is fatigue failure of working reinforcement. Operation mode of steel reinforcement in reinforced concrete constructions is non-stationary irrespective of loading conditions in these cases determination of fatigue resistance of reinforcement requires a great number of experiments which requires a great number of financial and manpower resources. The aim of the work is to develop a theory of fatigue cracking of steel reinforcement to create design models of reinforcement with cracks, for this purpose it is necessary: to establish the scheme of fatigue crack formation in reinforcement rods for reinforced concrete structures; to develop the equation of change in specific energy of steel fracture in the zones of crack formation and development; to develop a methodology for calculating the durability of steel reinforcement with cracks.

Studies were carried out to identify the economic feasibility of manufacturing hollow-core floor slabs with a height of 220 mm, having round voids with a diameter of 159 mm, non-tensioned reinforcement (series 1.141-1, issue 60) and prestressed reinforcement class A800 (series 1.141-1, issue 63), from high-strength sand concrete of classes VPB60 and VPB80 in comparison with slabs of heavy-weight concrete of classes B15 ... B80 in relation to the city of Kazan. The research is due to the absence of large aggregate deposits in a large part of the European territory of the Russian Federation or the presence of deposits of sedimentary rocks that are of limited use in reinforced concrete, with the widespread presence of sand, as well as the well-known economic efficiency of using high-strength concrete in the manufacture of loadbearing structures. The objectives of the research consisted in comparing the technical and economic indicators of slabs made of high-strength sand concrete of classes VPB60 and VPB80 with indicators of slabs made of heavy-weight concrete of classes B15 ... B80. The studies were carried out by the engineering method of calculation according to the current standards using the MS Excel PC. The strength and deformation characteristics of highstrength sand concrete were taken based on the results of studies of the Department of technology of building materials, products and structures (Kazan State University of Architecture and Engineering), obtained for concrete on the sands of local deposits.

The aim of this work is to establish the effect of various barium salts, as well as their concentration on the chemical composition of the products formed during their interaction with sodium hydrosilicates. The research objectives are to determine the effect of the concentration of barium salt on the chemical composition of the products of hydrochemical synthesis; to establish the type and concentration of the precipitating salt, which ensures the maximum efficiency of the product intended for the modification of cement systems - barium hydrosilicates, as well as the stable chemical composition of the precipitation products.

The purpose of this work is to develop a methodology for accelerated climatic testing of wooden structures treated with antiseptic, by means of testing and setting service life taking into account the actual climatic conditions of operation. The main task of this work is due to the need to clarify the method of forecasting the durability and long-term strength of wood in loaded building products and the physical justification of the method for increasing them by impregnation with special liquids.

One of the directions of the strategy of scientific and technological development of the Russian Federation is the development of new effective building materials with a complex of high operational and special properties. The special properties of shungite rocks determine the relevance of their use in compositions based on mineral binders to give them special properties. Without diminishing the significance of the existing research in this area, it should be noted that the problem is insufficient knowledge of the features of the processes of structure formation of cement stone modified with ground shungite in combination with mineral and chemical additives, which hinders the widespread use of shungite in concrete technology. The purpose of the research consists in the study of the special aspects of the phase constitution of cement stone modified by finely ground shungite, metakaoloin and plasticizing additive by infrared spectroscopy, which could be matrix of shungite containing concrete with special properties.

One of the main stages in the design of ventilation and air conditioning systems in a building is the calculation of air distribution in the premises. The energy and economic efficiency of the selected ventilation and air conditioning systems directly depend on the accuracy and correctness of calculations of air distribution in the premises. By changing the feed angle, it is possible to provide the necessary microclimate parameters without using additional equipment, and thereby optimize the costs of ventilation and air conditioning. The aim of the work is to verify the numerical model of the process of the outflow of an air stream flowing out at an angle of 45 degrees to the horizon into a ventilated room, and to determine the dependence of the characteristics of the stream on the location of the inlet behind the bend. To achieve this goal, the following tasks have been identified: to carry out a numerical study of the jet flow from the inlet, located at different distances from the rotation of the air duct by 45 degrees, and also to determine the patterns of change in the geometric and kinematic characteristics of the jet depending on the distance between the rotation of the air duct and the inlet.

In accordance with the decision of the Government of the Republic of Tatarstan on the need to develop a concept for the development of historical settlements of Tatarstan, a temporary creative team was created at Kazan State University of Architecture and Engineering to prepare a similar concept for the town of Chistopol. At present after analyzing the situation, the team has prepared a conceptual proposal for the urban development of the city, including a roadmap of events. The proposal is based on human, historical, urban planning and economic resources of the territory.

The article deals with a range of problems associated with the development and reorganization of post-industrial territories in the central part of the city of Kazan. The main goal of this study is to form a classification of post-industrial territories, to assess the current state of the selected areas, to formulate promising ways of developing postindustrial territories, taking into account existing project proposals, the general plan of Kazan, as well as methods of global experience of reorganization in large cities.