To reveal the influence of ultra-close coal seams mining on surrounding rock disturbance, PFC^2D is introduced to establish a simplified particle flow model of strata in the deeply buried mine, the damage and stress evolution characteristics of the surrounding rock were studied based on double coal seam mining. The results show that after the model excavation, the fracture length of the rock strata reached an accuracy of 97% compared with the theoretical calculation results, showing a good match with the theoretical calculations and the initial stress level obtained by the subsequent model monitoring is consistent with the measured value. The primary and secondary key layers are broken as a result of mining the higher coal seam, the siltstone interlayer is unaffected while the bottom coal seam is partially harmed, and there is noticeable extrusion damage between the rocks. Meanwhile, the damage to the rocks inside the gob is only becoming worse as a result of mining the lower coal seam. While the surrounding rock of the upper coal seam mining exhibits clear stress redistribution features in three zones, the lower coal seam mining creates a local and multi-point high-stress distribution. The siltstone interlayer’s stress variation is essentially identical to that of the surrounding rock. The extrusion state among rocks is related to the porosity of the shattered surrounding rock area. The siltstone interlayer is pressured during the upper coal seam mining, but it maintains its integrity, only collapsing during the lower coal seam mining. Though the siltstone interlayer can retain the necessary integrity of support before the lower coal seam mining, its internal stress is unstable which should be paid attention to when designing the support scheme during the mining period.

Recycling crushed coal gangue as concrete aggregate enables the clean, low-carbon, and sustainable disposal of coal gangue. This paper systematically investigates how gangue lithology and aggregate grading parameters jointly affect the mechanical properties and mixture design of coal gangue concrete. Test results show that higher grading parameters of coal gangue aggregate improve concrete workability. For grading parameters under 0.4, compressive strength fluctuates with water–cement ratio, whereas it decreases monotonically with increasing water–cement ratio when grading parameter exceeds 0.4. The optimal mixture is determined as water–cement ratio 0.6 and grading parameter 0.6. Mudstone gangue drastically modifies the compressive stress–strain behavior of gangue concrete. Compressive strength and elastic modulus drop by 28.3% and 22.4%, respectively, as mudstone content increases from 0% to 75%, with sharp mechanical degradation observed beyond the 75% threshold. As mudstone proportion rises from 25% to 100%, the dominant failure mode shifts from interface debonding and matrix cracking to a composite failure involving interface debonding, aggregate fracture and matrix rupture. For on-site construction, supplementary non-argillaceous gangue is recommended for mixtures with a mudstone content over 75% to maintain acceptable mechanical performance of coal gangue aggregate concrete.