Characterization of arching effect and failure mode of longwall panel floor. (August 2022)

• Record Type: Journal Article
• Authors: Liu, Yihong; Zhao, Hongbao; Ding, Huan; Li, Yue
• Is Part Of: Engineering failure analysis. Volume 138(2022)
• Publication Date: 2022-08
• Subjects: Floor -- Stress arch -- Mechanical characterization -- Unloading -- Failure zone; System failures (Engineering) -- Periodicals; Fracture mechanics -- Periodicals; Reliability (Engineering) -- Periodicals; Pannes -- Périodiques; Rupture, Mécanique de la -- Périodiques; Fiabilité -- Périodiques; Fracture mechanics; Reliability (Engineering); System failures (Engineering); Periodicals; Electronic journals; 620.112
• DOI: 10.1016/j.engfailanal.2022.106427
• Languages: English
• ISSNs: 1350-6307

Abstract

Highlights: There is elliptical stress balance arche in goaf floor. The mining effect leads to a shear stress increment on the initial principal stress surface of the goaf floor, resulting in the deflection of the principal stress direction. The concentrated stress of goaf floor transmitting along an arch trace. During the evolution of stress arch in floor, the floor will be unloaded. The goaf floor went through a process of arch foot stress concentration and high unloading, which intensifies the degree of crack propagation and fracture of the floor. The goaf floor is prone to generate tensile cracks, and the microcracks are prone to be in the same orientation and connected with each other to form a macroscopic fracture surface, thus resulting in significant expansion of the volume of goaf floor. With the advancing of the mining face, both the maximum tensile failure depth and the maximum shear failure depth of the floor increase accordingly, and finally tend to be stable. Abstract: The stress arching mechanism of longwall panel floor were studied by theoretical analysis, numerical simulation and field observation. The study results show that: the direction of the principal stress on the floor is deflected in the process of mining, so the concentrated stress of floor transmits along an arching line. The goaf floor went through a process of high unloading, which intensifies the degree of crack propagation and fracture of the floor. Microcracks in floor are likely to connect with each other to form a macroscopic fracture surface, which leads to a significant volume expansion of goaf floor. There is a terrace-like tensile plastic zone in the goaf floor and an arched shear failure zone exists outside the tensile plastic zone. Field monitoring results reveal that the goaf floor is dominated by unloading tensile failure, and the floor in front of the mining face is dominated by shear failure.