Abstract
The characteristics and mechanical mechanism of coal-seam floor unloading disturbance damage serve as important theoretical basis of rock-burst warning and other projects in deep mining. Many field situations show that dynamic disasters such as rock burst occur under the condition of low horizontal stress during deep mining. Therefore, the existing 2D stope ground-pressure theory based on shallow mining cannot fully guide the deep-mining practice. To explore the redistribution law of a three-dimensional stress field and the mechanical behavior of rock strata in deep stope-floor rock, we use numerical simulation, laboratory experiment, and field measurement to study the stress-field redistribution and mechanical-response characteristics of rock strata disturbed by the unloading of floor in a deep-mining area under strong unloading. Results show that the disturbance stress field of a floor rock layer in deep stope has spatiotemporal difference. Vertical stress is relieved layer by layer from top to bottom, and the level of horizontal stress is low. A high horizontal-stress-concentration area exists at the boundary of a stope. The critical yield load of the floor rock in a stope is solved by the thin-plate yield theory. Under the combined action of concentrated high horizontal stress and vertical rebound stress, the floor rock breaks layer by layer from top to bottom when it reaches the minimum buckling critical load, and the broken rock layer slides along the fracture surface, leading to floor heave. The maximum displacement area and failure area of the floor rock are located in the low-stress area above the inner boundary of the stress shell of the floor rock of the stope. In this stress area, dynamic disasters such as rock burst are easy to induce, so it is unsuitable for roadway layout. These results provide theoretical reference for the early warning of rock burst in deep stope-floor engineering to achieve dynamic control of a disaster-pregnant environment and reduce or change the disaster-causing conditions.
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This research was supported by the National Science Foundation of China (52004004 and 51974008) and the China Postdoctoral Science Foundation (2019M661991).
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Li, J., Guo, P., Yuan, A. et al. Failure characteristics induced by unloading disturbance and corresponding mechanical mechanism of the coal-seam floor in deep mining. Arab J Geosci 14, 1170 (2021). https://doi.org/10.1007/s12517-021-07526-0
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DOI: https://doi.org/10.1007/s12517-021-07526-0