Mechanical characteristics and damage evaluation of rock-coal-rock composite structure under compressive stress using AE technology
Guangjian Liu,Yong Niu,Dalang Tian,Yunjin Hu,Yongwei Wang,Liang Fu
Abstract
The sandwich composite structure formed by roof rock, coal pillar, and floor rock significantly affects the stability of mining areas. Simultaneously, the instability processes of composite structure need to be diagnosed by rational monitoring technology. In this study, uniaxial compression tests are implemented on the rock-coal-rock combination structures using the acoustic emission (AE) technology. The effects of the thickness of interlayer coal and loading speed on the mechanical responses and the AE behaviors of combined body are investigated. The minimum thicknesses of interlayer coal and loading speeds both evidently affect the elastic modulus and the peak strength of combined body. The evolutionary paths with the "U" type in the AE-ER curves gained by the inter-event time function can reliably characterize the macro-cracking process of composite body. The evolution characteristics of historic index (HI) and severity (Sr) acquired by the intensity analysis (IA) method can reliably characterize the cracking process of composite body. Five regions in the chart of IA are determined by the different cracking processes of composite body. The statistical distribution characteristics of HI and Sr in the five regions can provide the early warning information related to the fracture damage of composite body. The interlayer coal thicknesses and the loading speeds both affect the failure mechanism of composite structure. The present results can provide guidance for safe and efficient production in mining areas.
Guangjian Liu — State Key Laboratory of Intelligent Deep Metal Mining and Equipment, Shaoxing University, Shaoxing 312099, Zhejiang China; Institute of Rock Mechanics, Ningbo University, Ningbo 315211, Zhejiang China
Yong Niu, Yunjin Hu — State Key Laboratory of Intelligent Deep Metal Mining and Equipment, Shaoxing University, Shaoxing 312099, Zhejiang China
Dalang Tian — Chongqing Survey, Design and Research Institute Co., Ltd. of CREEC, Chongqing 400023, China
Yongwei Wang — School of Civil Engineering and Architecture, Hainan University, Haikou 570228, Hainan China
Liang Fu — Sichuan Shudao Railway Investment Group Co., Ltd, Chengdu 610093, Sichun China
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