Study on fracture-creep synergistic evolution of layered phyllite roadway and dynamic control of yieldable support

This study addresses the stability of layered phyllite roadways in deep mining. Using phyllite specimens with bedding angles of 0°, 30°, 45°, 60°, and 90°, a series of uniaxial, triaxial, and creep tests were conducted. The results demonstrate that both the strength and creep parameters of phyllite exhibit a U-shaped distribution relative to the bedding angle (peak strength: 90° > 0° > 30°–60°, with the latter being only 24.9 %–35.8 % of the 90° specimens). Failure modes are predominantly controlled by bedding angle: compression-shear failure along bedding planes dominates at 30°–60°, while tensile failure prevails at 60°–90°. Confining pressure suppresses crack propagation along bedding planes in medium-to-high-angle specimens and adjusts the shear plane angle in low-angle specimens. Creep behavior is significantly influenced by confining pressure: uniaxial creep manifests as compression-shear-tensile failure (with secondary cracks), whereas triaxial creep transitions to single-plane shear failure. Both elastic modulus and viscosity coefficient follow U-shaped distributions. Confining pressure more effectively inhibits creep in 0° and 90° specimens, while creep in 30°–60° specimens remains bedding-controlled. Based on these findings, an innovative ''yield-control support technology'' was proposed. For roadways with 30° bedding, a synergistic system comprising ''rock bolts (0.6m × 1.0m spacing)+buffer layer (20cm thickness, 0.22GPa modulus)+steel arches (0.4m spacing)'' was designed. This system effectively regulates surrounding rock deformation through energy absorption by the buffer layer and coordinated deformation control via bolts and arches. Simulation verifies the theoretical validity and engineering applicability of this technology for ensuring roadway stability under deep mining conditions characterized by high stress, high pressure, and strong disturbance.