A plastic-damage approach to the excavation response of a circular opening in weak rock. (August 2022)

• Record Type: Journal Article
• Authors: Guan, Kai; Zhu, Wancheng; Yu, Qinglei; Cui, Lan; Song, Fei
• Is Part Of: Tunnelling and underground space technology. Volume 126(2022)
• Publication Date: 2022-08
• Subjects: Ground response curve -- Rock damage -- Excavation damaged zone -- Strength-stiffness degradation -- Confining stress dependence; Tunneling -- Periodicals; Underground construction -- Periodicals; Tunnels -- Periodicals; Underground areas -- Periodicals; 624.193
• DOI: 10.1016/j.tust.2022.104538
• Languages: English
• ISSNs: 0886-7798

Abstract

Graphical abstract: Highlights: A plastic-damage method considering inelastic behavior is developed to predict GRC. Damage-induced inelastic response is significant for strain-softening rock mass. The preliminary critical support pressure for the residual failure zone is given. Abstract: During opening construction, the accumulated wall displacement and the developing excavation damaged zone are the results of stress redistribution and inelastic behavior induced by both the microcracking damage and the irreversible plastic deformation. The current approach to predict ground response to excavation disturbance is usually based on the Convergence-Confinement Method, which fails to consider the rock damage and the plastic-damage coupled mechanism, resulting in inaccurate estimation of rock deformation, particularly in the case of the weak rock with high deformability. This study establishes a plastic-damage theoretical approach for a circular opening by a kinematic decomposition of strains into an elastic, plastic and damage parts within the framework of finite strain using a hypoelastic–plastic theory, in order to investigate the inelastic behavior-induced excavation response. In this regard, the damage model provides the effective stress to the plasticity model defining the yield criterion, in combination with the strength-stiffness degradation and damage evolution. The numerical implementation is given and two examples are considered for validation. Extensive works are then carried out to clarify some issues, including the capacity of the model to characterize the inelastic behavior, the role of rock damage and confining stress dependence on ground response, and the preliminary critical support pressure for the residual failure zone.