<p>A true triaxial shear test method that integrated static and dynamic under true triaxial conditions was proposed to simulate the intricate shear mechanical behaviors and failure mechanisms of foliated rock surfaces due to tunnel excavation unloading and dynamic disturbances. This study employed a newly developed dynamic true triaxial shear apparatus to investigate the shear strength, deformation, failure surface morphology, shear strain rate, and damage progression of thin-foliated slates under varying lateral and normal stresses. The critical disturbance shear strength exhibited a significant dependence on lateral stress, initially increasing by as much as 7.5% before decreasing to −&#xa0;34.25% as the lateral stress intensified. A three-dimensional shear strength model incorporating lateral stress effects was formulated, with theoretical outcomes closely matching those observed in the experiments. Throughout the true triaxial shear tests, the thin-foliated slate displayed minimal disturbance shear deformation, low shear strain rate, and consistent damage values before failure occurred. Micro-tensile fractures were predominantly observed early in the disturbance phase. As the process progressed, the number of micro-shear fractures increased, ultimately forming a failure pattern dominated by a combination of tensile and shear cracks. In addition, pronounced precursory signals were observed prior to the onset of disturbance shear failure. The acoustic emission parameter lg<i>N/b</i> remained low and stable before sharply increasing near the point of failure. Consequently, disaster warnings for foliated tunnel surrounding rock should prioritize monitoring techniques that track the fracture development.</p>