Integrated Influence Zone Calculation Method for the Existing Metro Tunnel Under the Influence of Adjacent Construction

Abstract

Adjacent construction around metro tunnels is a common situation in urban cities, which usually leads to the disturbance of surrounding soils and existing tunnels. Based on the influence zone theory, construction risks can be described in a graded manner. However, the calculation of the influence zone in existing research is mostly based on a single indicator, which is difficult to adapt to the increasingly stringent requirements of real projects. To address this limitation, a normalized method for the influence function and a weighted combination method for multi-indicators were proposed. These methods can combine any number of indicators to obtain an integrated result of the influence zone, facilitating direct guidance of engineering. Based on a case study of the Metro construction in Qingdao, a series of numerical simulations and calculations of the integrated influence zone was carried out. The results show that the shape of the integrated influence zone in this case is a necked bottle, i.e., the new tunnel causes a greater influence when it is below the existing tunnel. The change of soil layer and the weight of indicators both play important roles on the shape of the influence zone. The relevant conclusions and methods provide a basis for the safety assessment of similar projects.