Abstract:Distortion of wall rocks during tunnel excavation is a key factor influencing the stability of tunnel structure and the safety in tunnel construction and use. Against this background, a triaxial compression test and FLAC3D-based numerical modeling are carried out to analyze the strain and failure characteristics of natural sandstones under different inner diameters and different unloading states. By comparison of the distortion properties of the specimens in the two tests, the following conclusions are drawn: under the same test condition, the tangential strain of the specimens increases with their size; the strain value under transient unloading condition is larger than that under slow unloading condition; the unloading effect under slow unloading condition is more sufficient; the tangential strain value obtained in the numerical modeling is smaller than that from the triaxial compression test, but the variation trend of the strain value in the two tests is basically the same.
