Experimental data for “Shear mechanical behaviors and cracking evolution mechanism of foliated slate in tunnel excavation disturbance condition” [Dataset]
Description
This study proposed a true triaxial shear test method combining static-dynamic under true triaxial conditions to simulate the complex shear mechanical behaviors and failure mechanisms of foliated rock surfaces, triggered by tunnel excavation unloading and dynamic disturbance. Based on a new dynamic true triaxial shear test device, the shear strength, deformation, failure surface morphology, shear strain rate and damage evolution rules of thin-foliated slate under different lateral and normal stresses were investigated. The critical disturbance shear strength of thin-foliated slate demonstrated a significant lateral stress effect, initially increasing by up to 7.5% and subsequently declining to -34.25% with increasing lateral stress. To describe this feature, a three-dimensional shear strength formula considering the lateral stress effect was developed with theoretical predictions closely aligning with experimental findings. During the process of the true triaxial shear tests, the thin-foliated slate showed the features of small disturbance shear deformation, low shear strain rate, and stable damage value changes prior to failure. In the initial period of disturbance shear deformation, micro-tensile cracks were primarily found. As the shear failure developed with the micro-shear cracks increasing, the failure mode of thin-foliated slate exhibited as tensile-shear mixed crack overall. Additionally, the disturbance shear failure precursors of thin-foliated slate are meaningful, acoustic emission parameter lgN/b maintained a low and stable level prior to disturbance shear failure, then sharply surged to a high value nearing failure. Therefore, disaster warning for foliated tunnel surrounding rock should emphasize monitoring aimed at fracture information.