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Jet grouting (JG) is a well-known and often used geotechnical technique suitable for various applications, such as underpinnings and foundation reinforcement. The downsides are its comparatively high CO2 footprint, caused by the high amount of cement used, and accumulating waste, i.e., backflow slurry. The former, cement, is recognized for its CO2 emission potential and we are seeing new binders being introduced as surrogates, a process driven by the cement industry. The latter, spoil, must be taken care of on site. Here, the use of centrifuges is a promising approach to reduce waste. Centrifuges offer a high throughput in relation to space requirements when compared with other systems, e.g., chamber filter presses (CFP). This paper presents exemplary projects which used jet grouting for foundation reinforcement. For our analysis we are using data from a construction site that worked both with and without a centrifuge during different stages of its production time. This allowed a more precise analysis than comparing two different sites. Using the calculated CO2 footprint and other parameters, the operation of the centrifuge is evaluated regarding its environmental and economic impact, Paper presentation

Introduction. One of the serious problems in the construction of underground structures in a dense urban area is the occurrence of excess deformations of the foundations of operating buildings that fall into the zone of influence of underground construction. The subject of the study was the calculated justification of the modern technology of compensatory injection. The relevance of the task is determined by the fact that the choice of the most effective protection technology should be based not only on a comparison of technological precipitation with maximum permissible values, but also on the assessment of the possibility of monitoring and controlling the movements of the foundations of buildings and structures during construction and subsequent operation. The purpose of the study was to compare various methods of protecting the foundations of existing buildings and structures and justify the selection of the most effective of them for further implementation and dissemination in the design and construction of urban underground structures. Materials and methods. On the basis of the survey data of the operated building falling into the impact zone of excavation of the pit for the construction of the installation and shield chamber of the subway, the parameters of the stress-strain state of its foundations are studied by mathematical modeling. The problem was solved by the finite element method based on the software and computer complex Z_Soil v.18.24. Results. Based on the analysis of the results of the examination of the administrative building using the finite element method, a change in the parameters of the stress-strain state of the foundations was modeled with various technologies for strengthening it. In the course of solving the geotechnical problem, it was found that the minimum impact on the foundations of the building during the construction of the pit was obtained in the method of compensatory injection. The system of criteria for making a decision on choosing an effective way to ensure the suitability of buildings in the underground construction zone for operation is substantiated. Conclusions. The results of this work can be used to justify the choice of technology for prevention and control of excess deformations of foundations. The function for calculating the volume of injected material in the Z_Soil software and computer complex can be used to justify the consumption of materials and the economic efficiency of the technological solution.

В данной работе были выяснены причины деформаций конструкций при эксплуатации существующего здания в результате технологических нарушений при возведении примыкающей подземной парковки. Были исследованы физико-механические характеристики измененного грунта для преобразования его строительных свойств. Определены возможные методы усиления, обеспечивающие дальнейшую безопасную эксплуатацию здания. Рассчитаны необходимые технологические и конструктивные параметры инъецирования. Разработан проект усиления кирпичных стен, фундаментов и грунтового основания в зоне максимального развития трещин в несущих конструкциях данного объекта. Выполнена укрепительная цементация грунтового основания здания под непосредственным контролем авторов рабочего проекта и данной статьи. При производстве работ и в течение последующего года эксплуатации здания осуществлен геотехнический мониторинг. В результате выполненных работ была достигнута стабилизация осадок грунтового основания здания и перемещений фундаментных конструкций. In this paper the reasons for structural deformations in the operation of the existing building as a result of technological errors at the construction of adjacent underground parking are clarified. Physical and mechanical characteristics of the amended soil to convert its structural properties are analyzed. We determine the possible methods of strengthening to ensure safe operation of the building. Necessary technological and design parameters of injection are calculated. We have designed the project of strengthening brick walls, foundations and soils of the basement in the zone of maximum development of cracks in the load-bearing structures of this object. Cement grouting of the building basement has been made under direct control by the authors of the project and this article as well. Geotechnical monitoring is performed during the works and within the subsequent year of the building maintenance. As a result of the performed works the stabilization of the settlements of the soil basement and displacements of the foundation structures has been achieved. Байбурин Альберт Халитович, доктор технических наук, профессор кафедры «Технология строительного производства», Южно-Уральский государственный университет (Челябинск), abayburin@mail.ru. Серебренникова Елена Николаевна, старший преподаватель кафедры «Строительные конструкции и инженерные сооружения», Южно-Уральский государственный университет (Челябинск), helen.silver@mail.ru. Куличкин Денис Владимирович, директор ООО «Ардис» (Челябинск), evn06@yandex.ru. Байбурин Денис Альбертович, директор ООО «Конструкционная Безопасность», интернет-ресурс ssafety.ru (Челябинск), dbayburin@mail.ru. A.K. Bayburin, South Ural State University, Chelyabinsk, Russian Federation, abayburin@mail.ru. E.N. Serebrennikova, South Ural State University, Chelyabinsk, Russian Federation, helen.silver@mail.ru. D.V. Kulichkin, Limited liability company “Ardis”, Chelyabinsk, Russian Federation, evn06@yandex.ru. D.A. Bayburin, Limited liability company “Construction Safety”, website: ssafety.ru, Chelyabinsk, Russian Federation, dbayburin@mail.ru.

The article is dedicated to foundation of buildup nine-storied combined ferroconcrete building 1970-80 years choice variants in the process of its energy efficient reconstruction with using special model "Choice-reconstruction", Статтю присвячено обґрунтуванню вибору варіантів надбудови дев’ятиповерхових збірних залізобетонних будинків 1970-80 років забудови в процесі їхньої енергоефективної реконструкції з використанням спеціальної моделі «Вибір-реконструкція».