Contributions to responses of existing tunnel subjected to nearby excavation: A review

Excavation nearby an existing tunnel is frequently encountered in underground construction, especially in congested urban areas. Essentially, the responses of the ground and existing tunnel to the nearby excavation is a complex soil-structure interaction problem. In this paper, extensive earlier contributions to this problem are organized according to their subject matters, including field observation, physical modeling, numerical simulation, and analytical method. This paper presents a review of selected representative researches that indicate the growing scenarios and an increase in our understanding of this problem. A summary of the limitations of each contribution is presented, as well as the expected aspects that need to be optimized in the future research. It is found that our knowledge is far from complete, and there are still gaps to be narrowed, particularly concerning the reliable measurement of soil stiffness, realistic modeling of excavation and tunneling construction, elegant soil constitutive models for natural soils, precise mechanical model and current status of the tunnel lining, etc. The review can help researchers and engineers to have a general knowledge of the relevant problem and provide guidance for more in-depth research.