Analysis of the surface subsidence induced by sublevel caving based on GPS monitoring and numerical simulation
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Analysis of the surface subsidence induced by sublevel caving based on GPS monitoring and numerical simulation Xingdong Zhao1 · Qiankun Zhu1 Received: 10 November 2019 / Accepted: 15 June 2020 © Springer Nature B.V. 2020
Abstract This paper describes a case study of the surface subsidence induced by sublevel caving without sill pillars in the Maogong Iron Mine, China. A comprehensive analysis based on GPS monitoring and numerical simulation is proposed and used to analyze the surface subsidence characteristics and damage range. GPS monitoring results showed that the vertical displacement reached 40.3 mm at the JC5 monitoring station and was accompanied by ground crack development. According to the in situ surface subsidence monitoring data and numerical calibration model results, the corresponding critical horizontal strain and angular distortion due to the surface subsidence were estimated as 1.5 × 10−3 and 2.0 × 10−3, respectively. The numerical results showed that the center of the surface subsidence was located in the hanging wall of the orebody, which changed to its far end with increasing mining depth. In the early surface subsidence stage, macro-tension cracks developed in the hanging wall rock mass, and the slabbed rock mass then collapsed into the cave through rotation and/or translation failure. With increasing mining depth, there will be unfilled goaf in the underground, and the rock mass will gradually collapse under high mining-induced stress concentration. Accumulation of caved rocks and the bulking effect result in slow surface subsidence. Notably, surface collapse will not occur suddenly in Maogong Iron Mine, and potential secondary hazards mainly small landslides in the hillside. Keywords Sublevel caving; surface subsidence · GPS monitoring · Numerical simulation · Critical strain
1 Introduction Surface subsidence is a geological hazard resulting from sublevel caving (Chen et al. 2016). Sublevel caving is a mass mining method based on utilizing the gravity flow of the blasted ore and caved waste rock. Sublevel caving without sill pillars is the main mining method used in underground metal mines in China (Li et al. 2006). Sublevel caving has the characteristics of safety, mechanization, flexibility and allows a favorable work schedule. * Xingdong Zhao [email protected] 1
Geomechanics Research Center, College of Resources and Civil Engineering, Northeastern University, Shenyang 110819, Liaoning, China
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Natural Hazards
To date, studies on sublevel caving have mostly focused on the gravity flow characteristics of fragmented ore (Stazhevskii, 1996; Brunton et al. 2010; Xu et al. 2017; Zhang et al. 2018), the ore loss and dilution control (Ryzhkov et al. 2002; Tao et al. 2019) and the caving state of the host rock and orebody (Li et al. 2011; Svartsjaern 2019). Moreover, sublevel caving causes surface subsidence in different ranges from few millimeters to several meters and has a destructive impact on surface buildings, structures and farmland (Nie et
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