The Prototype Test on Sealing Capacity and Mechanical Behavior of the Underground Segmental Lining in a Low Vacuum Environment

The super-speed tube transport (SSTT) system is called the fifth traffic mode internationally. One of the critical technical problems for the design of SSTT system is the sealing reliability in vacuum tube structures. In this paper, an experimental study of the sealing capacity and mechanical behavior of the segmental lining is carried out, and the following conclusions are drawn. To meet the requirements of the SSTT system, the existing sealing of the concrete segment structure needs to be further strengthened. The joint spacing decreases with increasing vacuum and increases with vacuum pressure relief. There is an obvious correlation between the strain change and the vacuum pumping, which can be divided into four stages. The influence of the pressure difference and the local airflow movement on the concrete surface strain is dominant by turns at different stages. The concrete surface is suggested to be reinforce on account of the tensile strain caused by the local airflow movement of vacuum pumping is significant. The relative pressure caused by vacuum has little effect on the stress and deformation of the structure. The results of the study can help to understand the sealing capacity and mechanical behavior of the underground segmental lining in a low vacuum environment and be beneficial in choosing the appropriate structure type for the SSTT system.