Characteristics of Fracture Mechanism and Acoustic Emission of Rock-Coal Combined Body with Prefabricated Fissure
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ORIGINAL PAPER
Characteristics of Fracture Mechanism and Acoustic Emission of Rock-Coal Combined Body with Prefabricated Fissure Deng Zhang . Chuanxiao Liu . Yan Zhou . Depeng Ma
Received: 4 April 2020 / Accepted: 20 June 2020 Ó Springer Nature Switzerland AG 2020
Abstract In order to analyze the mechanical characteristics of the composite rock sample, numerical simulations for the rock-coal combined body with a coal persistent joint are conducted using RFPA2Dsoftware. Effect of the joint angle and height ratio on the uniaxial compressive strength (UCS) and acoustic emission (AE) characteristic in rock-coal combined body were analyzed. The results show the following. (1)With the increase of joint angle, the peak strength and peak strain first decrease and then increase, presenting ‘U-shape’ curves; With the increase of rock-coal height ratio, the peak stress increases gradually and the peak strain decreases gradually; (2)The different joint angle of prefabricated fissure affects the failure form of rock-coal combined body, but the height ratio of rock-coal has less influence on the failure form of the composite rock sample; (3)When the coal sample in the combination is near to failure, the AE energy accumulation curve will show a slow step shape curve and then a sudden increase. This phenomenon will occur in the combined
D. Zhang C. Liu D. Ma (&) School of Water Conservancy and Civil Engineering, Shandong Agricultural University, Tai’an 271018, People’s Republic of China e-mail: [email protected] Y. Zhou Department of Resources and Civil Engineering, Shandong University of Science and Technology, Tai’an 271019, People’s Republic of China
samples with different combination modes, which can be used as a precursor to the failure of the rock-coal combined body. Keywords Numerical simulation Prefabricated joint Rock-coal combined body Acoustic emission Strength-strain
1 Introduction Most of mineral resources are obtained through underground mining. With the gradual reduction and depletion of shallow resources, the depth of underground exploitation is more and more. With the increasing depth of exploitation, engineering disasters are increasing, such as mine impact pressure, gas explosion, mine pressure obviously intensified, roadway rock deformation, geothermal rise, etc., which pose a great threat to the efficient mining of deep resources(He et al. 2005). At present, the mining of coal resources in China has entered the deep mining stage, and most of the shallow coal resources have been developed. In the process of deep coal mining, not only the coal will be affected by mining disturbance, but also the rock mass of coal body roof and floor will be affected. Therefore, in the process of deep coal body mining, the whole ‘‘surrounding rock-coal
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Geotech Geol Eng
body’’ system is affected by mining disturbance (Xie et al. 2015). At present, most researches focus on the mechanical characteristics and failure characteristics of single coal body and single r
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