New Method of Surface Settlement Prediction for Saint-petersburg Metro Escalator Tunnels Excavated by EPB TBM

Abstract

The article describes a new technology of escalator tunnel construction using earth pressure balance tunnel-boring machines (EPB TBM) in complex geological conditions of St. Petersburg soils. The results of field surveying observations of settlements and strain calculations arisen from the construction of the escalator tunnels of the St. Petersburg metro “Obvodny kanal”, “Admiralteyskaya”, “Spasskaya” stations are presented. It is established that the evolving strain can be dangerous for undermining buildings and structures. The method of escalator tunnel construction numerical modeling based on the finite element method is used to evaluate the qualitative relations of the geomechanical processes. A new method of surface settlement prediction is based on the results of complex processing of field data and results of construction numerical modeling. This method involves determination of the following characteristics of the displacement process: the position of the point of the maximum settlement in a subsidence trough, the size of a subsidence trough, the value of the maximum settlement, distribution of displacements and strains in the trough. The developed method for calculation of the settlements was tested on Saint-Petersburg metro escalator tunnels. Comparison of results for predicted and observed data indicate the reliability of the developed settlement and deformation prediction method in the construction of the escalator tunnels using the TBM in St. Petersburg.