Physical model test to control large deformation using airbag resistance limiter support

Tunnel construction in mining and civil engineering is expanding rapidly worldwide. However, excavating tunnels in soft rock under high-stress conditions presents substantial challenges, including large deformations and support system failures, which significantly affect both safety and cost. Current research on effective deformation control measures remains limited, underscoring the need for improved support systems, and particularly the exploration of high-performance tunnel lining materials. To address these issues, this study investigates the characteristics of large deformations in soft rock tunnels and proposes a novel composite support strategy combining "rock + airbag resistance limiter as flexible support + rigid support", in which a full-section circular lining is overlaid with an airbag resistance limiter to control excessive deformation. The feasibility and effectiveness of this support system were evaluated through laboratory model tests designed to induce large deformations in the surrounding rock, with displacements and strains measured at multiple locations. Experimental results demonstrate that the airbag resistance limiter support system limited the maximum vertical and horizontal deformations of the surrounding rock to −4.40 mm and −3.51 mm, respectively. Additionally, a relatively uniform strain distribution was observed, indicating stable mechanical behavior under the tested conditions. This study preliminarily verifies the feasibility of the proposed support concept in a controlled experimental setting; however, further validation through field applications is required. The findings offer useful experimental insights and a foundation for future research and potential engineering implementations in soft rock tunneling.