Study on Ring Shear Creep Mechanical Properties and Creep Model of Carbonaceous Shale With Different Water Content

As a typical weak interlayer in slopes with soft and hard interbedded structures, the mechanical properties of carbonaceous shale are significantly affected by water content. Ring shear and ring shear creep tests under various water content conditions were conducted to systematically analyze their shear strength and creep characteristics. Based on fractional‐order theory, a water‐content damage fractional‐order Burgers creep constitutive model was established and employed to fit the test data and identify parameters. Results show that (1) peak shear strength, residual strength, and long‐term strength decrease with increasing water content, with cohesion being more sensitive. (2) Instantaneous shear modulus declines significantly as water content rises, an effect far exceeding that of shear stress. (3) The established model accurately describes three‐stage creep, with fitted curves agreeing well with test data (average R 2 > 0.95). This study provides a theoretical basis for long‐term stability assessment and hazard warning of soft‐hard interbedded slopes.