Yielding performance of compact yielding anchor cable in working state: Analytical theory and experimental evaluation of yielding resistance enhancement effect

Abstract

To elucidate the yielding performance of compact yielding anchor cables in working state, a yielding mechanical model incorporating extrusion friction and fastening rotation under confining pressure is constructed. The yielding resistance enhancement effect (ω) caused by working environment constraints is evaluated through multi-layer composite sleeve hole expansion analysis, forming a theoretical framework for calculating the working yielding force. Laboratory and in-situ pull-out tests are conducted to determine the yielding performance and validate the analytical theory. The main conclusions are: (1) Yielding force and energy-release capacity increase with ω, significantly outperforming the unconfined state. (2) In-situ tests under varying rockmass and geostress conditions (F1–F3) determine the yielding force increases to 183.4–290.1, 204.0–290.8, and 235.0–327.1 kN. (3) The slight deviation (–12.5% to 6.2%) between the theoretical and measured yielding force confirms that the analytical theory effectively describes the working yielding performance. (4) ω increases with higher geostress and improved rock mechanical properties, with initial geostress (σ₀) and elastic modulus of surrounding rock (E₃) identified as critical parameters.