ABSTRACT
This study aims, in the first place, to establish a technical definition of large opening in circular shafts from the perspectives of soil, structure, and soil-structure interaction. Parametric studies have been carried out using different approaches to analyze the consequences of the opening. Structurally, the opening results in a loss of rigidity, causing ovalization of the structure and both vertical and horizontal bending moments. The asymmetry in the vertical balance leads to a tilting of the structure’s upper part. Additionally, significant local stresses around the opening must be considered for the design of reinforcements. Quantifying these consequences will help determine what constitutes a large opening and facilitate the shaft design. The geotechnical study is based on an analysis of soil-structure interaction, using finite element method. Simplified two-dimensional models and three-dimensional models were considered and compared. This addresses a crucial problem in dense urban areas: the estimation of ground settlement, in particular induced by opening. A sensitivity study on several geometric and geotechnical parameters was carried out to assess their importance.
