Buildings and tunnel structures protection from excess sedimentary deformations in the area of foundation pits construction influence

The article discusses the process of performing construction and installation work on the foundation pits construction near the existing metropolitan railway tunnels in dense urban areas. The authors consider one of the most effective ways to reduce the negative impact of excavation on two existing single-track tunnels — compensation grouting. Compensation grouting is performed to ensure the safety and operational reliability of existing metropolitan railway facilities located in the area of influence of objects under construction, in the case considered by the authors, in the area of influence of the foundation pit being constructed. The article outlines the main provisions for the implementation of drill and injects work. The technological process of work performance based on compensation grouting is capable of ensuring the almost complete absence of sediment during the operation of tunnels during the construction of the excavation. Preservation of tunnels in the planned — high-altitude position is carried out based on monitoring the state of the calculated level of pre-stress in the soil volume, which is located between the tunnel and the excavation fence. The authors describe the design and technological features of the use of compensation grouting to ensure the metropolitan railway tunnels’ operational reliability, provide a calculation justification for the main technological parameters, create design schemes, present the results of the calculation in the form of tables, and describe the technology for performing work. The results analysis was performed, for which the values of the prestress in the soil were used, as well as the possible movements of the rail tracks in the distillation tunnels during the excavation under the compensation grouting protection. The design solutions proposed by the authors, based on the compensation grouting technology to create preliminary stress in the soil, make it possible to ensure the maintenance of the operating regime of tunnel structures near the objects under construction.