A physical model test for the stress and deformation analyses in underground caverns containing block during excavation

Abstract

In order to investigate the influence of block on the stress and deformation of underground cavern with high sidewall during excavation and unloading, a physical model test of an underground cavern containing block was conducted based on similarity theory. The response pattern of surrounding rock stress and displacement during excavation is analyzed, and the influence and mechanism of block on surrounding rock stress and deformation are revealed. Results show that stress conduction in the model is closely related to the structural plane during loading. The stress barrier and stress concentration phenomena occur when stresses pass through the structural plane. After the model is loaded, stress loss takes place when stresses are transmitted from the boundary to the interior. During the underground cavern excavation, the tangential stress of the surrounding rock decreases within a certain range of the sidewall and increases at both the top and the shoulder of the arch. The change rate of stress before and after excavation is used as an index to determine the surrounding rock stress zone, and the influence range caused by excavation is 2.0–2.5 times the cave span. Compared with the sidewall without block, the sidewall with block has a smaller radial stress unloading zone and a larger tangential unloading zone.