An entry-scale numerical modeling approach to developing ground reaction curves for standing support performance evaluation of longwall gateroad entries

The longwall gateroad entries are typically subjected to significant stress and ground deformations which are induced by mining activities, rendering them vulnerable to extensive roof collapses, floor heaves, and sidewall spalling. The Support Technology Optimization Program (STOP), with site-specific Ground Reaction Curves (GRCs), has been extensively utilized to evaluate the performance of standing support systems in gateroad entries. However, measuring GRCs in-situ in underground mines remains impractical, and only a few GRC samples are available in the STOP program. In this research, an entry-scale modeling approach was developed, based on the numerical program of the FLAC 3D , in order to enhance the application of the STOP program with the local geology- and stress-dependent GRC. A case study at a Northern Appalachian coal mine was used in this study to illustrate the whole modeling procedure for site-specific GRC development and standing support performance assessment. Modeling results were compared to field measurements, and the obtained results were in good agreement with the measured data on roof deformation and support load. The R 2 value was 0.91 and the root mean square error was around 0.99 for the roof deformation validation, while the relative error averaged at around 11.8% for the support load verification. The STOP program results also show that the loading density on wooden cribs ranged from 250 kN/m using the weakest crib to 850 kN/m using the default crib with 2 rows spaced at 238 cm under the tailgate stress state. It is concluded that the proposed modeling approach, together with support system database from STOP, could simulate the ground response of a gateroad entry and generate a site-specific GRC for standing support system performance evaluation. The developed geology- and stress-dependent GRC can be integrated into STOP to help optimize the standing support design. The research can provide insights into the optimized support design of gateroad entries of underground excavations in the mining engineering field.