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The Double-Yield (D-Y) model is a widely used method for predicting the mechanical properties of caved rock. However, determining the numerical simulation parameters for this model typically requires extensive trial and error. In this paper, a new approach for parameter inversion of the D-Y model is proposed and applied to a real case study involving repeated mining in multiple coal seams. The proposed framework combines FLAC3D, a finite element numerical simulation software, with a new computational tool developed using MATLAB® App Designer. By applying this framework to the case study, the accuracy and efficiency of parameter determination in the mining area are improved. In addition, a 3D finite element model of multiple coal seams is generated based on the geological information of the case study, and the stress evolution is analyzed. The simulation results are then validated through field measurements, providing valuable reference information for safe and efficient production. Overall, this improved method for parameter inversion of the D-Y model, along with the combined numerical simulation and field measurement approach, enhances the understanding of stress evolution in multiple coal seams and contributes to safer and more efficient mining operations. Highlights: An in-depth analysis was conducted to examine how variations in Double-Yield parameters impact the numerical simulation curve. A breakthrough approach for parameter inversion of the Double-Yield (D-Y) model is introduced, and the computational tool is developed. A 3D finite element model is crafted to analyse the dynamic stress evolution during repeated mining of multiple coal seams. The accuracy of simulation outcomes is bolstered by validation against field measurements of mining-induced stress. [ABSTRACT FROM AUTHOR]

While large-scale rock strata affected by underground coal mining have been widely studied through numerical modeling, there are still some aspects that can be better understood. Specifically, researchers do not fully utilize borehole logs and test results of rock specimens to reveal rock mass property variation along horizontal directions and strata lateral thickness variation at bed level. In this paper, we address this knowledge gap by proposing a data-intensive numerical modeling method (DINMM) that can make full use of these data with consideration of the modeling limitations of BlockRanger, a grid generation tool. Both the proposed method and the conventional numerical modeling method (CNMM) are applied to the Ying-Pan-Hao coal mine via the FLAC3D (Fast Lagrangian Analysis of a Continua in 3 Dimensions) package, and their predictions are then calibrated and compared to discuss the validity. Results show that, compared to the CNMM-based predictions, the root mean square error of 70 monitoring points is decreased at least by 27.4% in the DINMM-based prediction, and the relative error of maximum subsidence is reduced by 5.1% with a reduction rate of 66.5% on average, even though the CNMM-based model was originally better calibrated. We also find that a DINMM-based model is more in line with field observations and theoretical understanding in terms of displacement, stress, and failure propagation. The notion of data-intensive modeling seems to be quite promising and the DINMM should be useful for a better understanding of strata movement and subsidence prediction. Highlights: • We propose a data-intensive modeling method (DINMM) to build numerical models based on multiple borehole logs, rather than on a single or generalized borehole log. • We realized rock mass property variation along horizontal directions and strata lateral thickness variation at bed level when modeling large-scale rock strata. • We find that the root mean square error of 70 monitoring points is decreased at least by 27.4% in the DINMM-based prediction, even though the control model was originally better calibrated. [ABSTRACT FROM AUTHOR]

Heat from gas explosions affects the physical and mechanical properties of rock and reduces the stability of tunnels, such as in coal mines. This paper mainly studies the physical and mechanical properties of sandstone after heating and investigates the influences and mechanisms involved. Acoustic emission (AE) monitoring, X-ray diffraction (XRD), scanning electron microscopy (SEM) and polarized light microscopy are used to show that the uniaxial compressive strength (UCS) and peak strain of sandstone change significantly with temperature. In particular, the UCS decreases rapidly at 500 ~ 600 °C due to a transition from α -quartz to β -quartz. The XRD analysis shows that the physical and mechanical properties of sandstone are affected by its mineral composition, as physical and chemical reactions of quartz, muscovite and kaolinite at high temperatures weaken the sandstone. The AE signals increase with temperature and correspond well with observed loading stages, as they reflect the spatiotemporal evolution in internal micro-cracks. The degree of crack opening is low at low temperatures, then cracks become connected with increasing temperature, further explaining the changes in mechanical properties. Polarized light microscopy shows that grain size and pore characteristics are related to mechanical strength; generally, higher strength is associated with smaller grains with a less even size distribution. In addition, thermal and mechanical damage were quantitatively characterized by deriving thermal, comprehensive and dynamic damage factors. The results provide a theoretical reference for mining engineering in high-temperature environments. [ABSTRACT FROM AUTHOR]