Physical model test on the support characteristic for quasi-NPR bolt under asymmetric stress

Abstract

With the continuous increase in tunnel construction, the significant deformation of the surrounding tunnel rock is often difficult to predict and control. In addition, the lithology, structure, and various asymmetric large deformation of surrounding rock mass during operation and maintenance severely affect the ultimate bearing and stability of the tunnel. To explore the deformation mechanisms and failure modes of surrounding rock under large asymmetric stress and complex geological conditions, a physical model of a tunnel through granite was constructed based on the similarity theory. The model had 30° dip lithology under asymmetric stress and was emplaced a new quasi-negative Poisson’s ratio (NPR) bolt. By analyzing the variation law of displacement and axial force of the bolt under an asymmetric load, the asymmetric deformation and failure mechanism of the granite tunnel and the support effect of the quasi-NPR bolt were determined. The energy absorbed by the surrounding rock was analyzed, and the influence mechanism and control countermeasures of asymmetric stress on the granite tunnel were explored. This work provides a reference for the design of asymmetric support of tunnels with similar engineering backgrounds.