Keywords: development

STABILIZATION OF SUBSIDENCE OF BUILDINGS OF MODERN MEDICAL CENTERS

https://doi.org/10.34031/2618-7183-2021-4-6-5-25
Abstract
The group of deformed structures includes buildings that have received unacceptable subsidence and deformation during the period of their construction and especially operation, which, however, do not interfere with the performance of their main functions, but may eventually collapse. Their causes are errors in engineering and geological surveys and design; violation of the rules for performing construction work and operation of buildings and structures. Long-term geodetic observations of the precipitation of the foundations of buildings on pile foundations have shown that both absolute and relative stabilized values of subsidence in the vast majority of cases are less than them and the normative limit values are calculated. Therefore, the group of deformed buildings on pile foundations includes somewhat less often similar objects with shallow foundations. The reasons for excessive subsidence of the foundations of pile foundations of buildings (and as a result, the occurrence and development of cracks and other deformations in load – bearing structures), in addition to these, are most often: unjustified use of increasing correction coefficients for the results of compression tests of highly acidic soils; the lower ends of the piles falling into layers of weak soil; the tip of the piles sinking from the design mark; overestimation of the bearing capacity of the piles due to non-compliance with the optimal time of their "rest" after immersion or erroneous interpretation of the graphs "load-pile sediment"; excessively close placement of neighboring piles in the plan, which when they are immersed, especially in the sand, leads to "pushing" up previously submerged; uneven loading of piles as part of the grillage; deformation of existing buildings and structures when driving piles near and tongue-and-groove, the development of pits, etc.
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OBTAINING A THERMAL INSULATION LAYER FROM MONOLITHIC NON-AUTOCLAVED STRUCTURAL AND THERMAL INSULATION FIBRE FOAM CONCRETE

https://doi.org/10.34031/2618-7183-2021-4-3-5-22
Abstract
The possibility of obtaining structural and thermal insulation foam concrete of non-autoclave hardening with improved construction and technical characteristics for the device of a thermal insulation layer in the con-struction of road pavement due to three-dimensional dispersed reinforcement with polypropylene fiber is theoretically justified and experimentally confirmed. Based on the results of studies of the influence of technological factors on the properties of foam concrete, the optimal content (up to 0.25% of the cement mass) and the length (12 mm) of reinforcing polypropylene fibers have been established, which allows obtaining high strength indicators of dispersed-reinforced cement stone for bending (an increase of 12-20%) and compression (an increase of 6-12%) compared with non-reinforced cement stone of non-autoclaved foam concrete. The analysis of the process of structure formation of dispersed reinforced foam concrete from the standpoint of a systematic approach based on multifactorial polynomial models of the influence of the ratio of filler and binder, as well as the number of dispersed reinforcing fibers, which is determined by the optimal conditions for the distribution of solid and gas phases, as well as the reinforcement of adjacent interstitial partitions of foam concrete, linking them into one asociate, which ensures the joint work of the material under various external influences. A method was developed to increase the durability of the road surface and eliminate the influence of the frost heaving effect on the quality of the road surface by introducing the necessary amount of effective thermal insulation layer into the road surface design. The analysis of the regularity of the heat transfer process in the soil mass of the roadbed and multilayer road pavement is carried out. Based on the analysis, the values of the necessary resistance to heat transfer of road pavement for the natural and climatic regions of the country are determined and a method for calculating the value of the thermal insulation (frost-proof) layer of road pavement is proposed. A method was developed for calculating the value of the thermal insulation layer using monolithic fibre foam concrete and a nomogram to determine the required value of the thermal insulation layer made of monolithic non-autoclaved structural and thermal insulation fibre foam concrete of classes D600-D1000.
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