For the First Time in the World: Jet-Grouting for Consolidation of Tunnel Foundation at the Operated Metro Line Between Kantemirovskaya and Tsaritsyno Stations

Introduction. Today, jet-grouting of soils has proven itself as an effective technology capable of solving various geotechnical problems. One of the areas of jet-grouting technology is to create soil-cement elements with specified strength and deformation parameters. Example of consolidating the foundation of tunnel lining of the operated track tunnels illustrates the possibility of successful use of jet-grouting technology in the space restricted by tunnel lining dimensions and limited by working hours during the so-called “night windows”. Aim. Determining the possibility of carrying out works using jet-grouting technology restricted by limited time conditions and tunnel lining dimensions. Materials and methods. To solve the set task and test the initial theoretical principles, empirical work was carried out on a trial site, with further analysis and adjustment of the results obtained. Results. A highly effective step-by-step scheme for the installation of soil-cement reinforced elements was developed, which for the first time in the world practice made it possible to carry out works to strengthen the tunnel lining in the operated metro tunnels. Conclusions. As part of the project to consolidate the foundation of the tunnel using jet-grouting technology, for the first time in the world practice, 1,120 soil-cement piles were installed in the operated metro track tunnels. This allowed to abandon the permanent water reduction system, as well as to operate tunnels in a standard mode, without any limitations of train speed.