(A) study on ground stability under vertical shaft excavation using ring cut method in clay

Abstract

As the demand for underground structures increases due to the densification of population and facilities in urban areas, researches are being actively carried out on the vertical shaft excavation that is essential for the construction of underground structures. During the excavation of a vertical shaft, problems such as boiling and piping piping phenomenon occurs due to inflow of groundwater. Also, basal heave that the excavation surface rises may occur in soft ground. There are problems such as noise, vibration and prolonged occupancy of the surrounding site depending on the excavation method. In order to solve these problems, Center for Utility Tunnel has developed Ring cut method, a low-noise, no-vibration, outer-circumference excavation method with improved performance of waterproof using biopolymer and with the performance of stabilizing the ground with wall penetration. In this study, the ground stability improvement performance of the proposed method is verified by experimental study. In addition, an equation that can predict the optimal wall penetration depth to maintain the stability of the ground during vertical shaft excavation using the developed method was proposed.