Technological solutions for excavation works in the process of implementation of the “top-down” approach
Introduction. Underground space development in the course of infill construction in confined spaces of megalopolises is a promising development trend in construction. To save the workspace, the “top-down” approach can be used. In this case, a substantial portion of the underground work consists in the soil development and loosening under the protection of beams, which is relevant for frozen soils in Central Russia. The analysis of regulatory documents and the studies, conducted in this area, has proven that there are no methodological recommendations on the arrangement of soil excavation in confined spaces. The purpose of the study is to analyze and systematize current methods of soil development and loosening and to evaluate their applicability in confined spaces. Materials and methods. The authors consider widely used excavation techniques (mechanical, hydro-mechanical, and explosive ones) and less widely spread soil development methods (electric pulse and thermal ones). The expediency of excavation mini-technologies, designed for works in confined spaces, is emphasized. Attachable hydraulic and electromagnetic machinery, used to loosen soils, is analyzed. The analysis of these methods shows their strengths and weaknesses, as well as the applicability of the “top-down” technique. Results. Combinations of machines designated for soil excavation and loosening within the framework of the “top-down” technique are made to further estimate the engineering and economic performance and their comparative analysis. The authors propose combinations of excavating machines that represent lightweight or mini-items having mounted soil loosening and excavation mini-machines. Conclusions. The practical value of the study consists in the analysis of available methods of soil excavation and loosening and the assessment of their applicability to the confined conditions of construction of substructures of buildings using the top-down technology, which is relevant for Central Russia. The authors made combinations of machines whose operation is mostly based on mechanical methods. The authors suggest considering the use of mini-machines and attachments.