Experimental investigation of the creep behavior of the bond interface in steel plate reinforced tunnel lining

One important strategy for increasing the strength and load-bearing capability of damaged tunnel linings is to reinforce them with steel plates. An important factor in determining the long-term performance of the restored tunnel is the bond interface’s longevity. This study focuses on the bond interface creep behavior in steel plate-reinforced shield tunnels through experimental investigation. Accelerated testing was used to investigate the long-term creep response of the bond contact using the creep equivalence and Boltzmann superposition principles. The key takeaways are as follows: The progression of creep at the bond interface – from the moment of initial loading to when it reaches a stable state – can be broadly broken down into four phases: an instantaneous deformation phase, a stage of decay creep, a period of steady–stable creep, and accelerated creep phase. The bond contact of the shear specimen experiences accelerated creep after 186 hours when it is subjected to 90% of its maximum stress, while the bond interface of the tensile specimen reaches this stage in just 96 hours. As the stress level rises, so does the quantity of creep at the bond interface. As the distance from the loading end increases for the shear specimens, the amount of creep at the bond contact progressively diminishes. A notable 1000-fold increase in creep time is seen when Time-Stress Superposition Principle (TSSP) is used to speed up the characterization of experimental creep curves for the bond contact.