Effectiveness of strengthening retaining structures based on the fan method of laying anchoring on urban underground facilities

The purpose of the work is study the construction of a retaining structure of the pit, in conditions of a significant height difference using a multi-tiered system of strand anchors.To assess the bearing capacity of the ascending anchorage, a combined approach to the formation of a multi-tiered anchorage is used.Methodology.The methodological basis for calculating the strength of enclosing structures is a numerical solution of the problem of a beam bending lying on an elastic-plastic base and held by anchor structures as couplings.Modeling of an ascending anchor structure is implemented in the operating environment of the GeoWall program.Based on the optimization of the method of laying the anchorage, it is planned to include the system of ascending anchors replacing the ground anchors on the first two tiers of the structural reinforcement of the retaining structure in the operation.Results.As a result of the analysis of the pit enclosure with a multi-tiered anchor system, it was stated that the ground anchors, on all four tiers, are not able to prevent soil decompaction around the excavation due to their malleability and, accordingly, the mobility of retaining structures.The problem of reliability is solved by switching to an ascending method of laying anchors of the first and second tiers.The stability of the retaining structure is radically improved by increasing the bearing capacity of the ascending anchorage along the ground, due to the involvement of an array of soil in the work, an increase in holding forces with active reinforcement of the pile row.Conclusions.The analysis of theoretical and experimental studies has shown that the practical result of the work is a radical change in the attachment scheme of retaining walls with a height difference of 15 m or more, due to the inclusion of an ascending anchorage system.