Maintaining surrounding rock mass stability of roadways is essential to the safety of deep coal mining. In this study, the No. 2‐2092 roadway of the No. 2‐209 mining face in Ganhe coal was taken as the target roadway for field analysis. The selected region can be considered a typical area with dominating geological tectonic stress, based on the geological survey and in situ stress results. A mechanical model of roadway overburdens was developed to analyse the large deformation and stress field distribution. It is found that the large deformation is caused by the combined superposed stress field including laterally transferred stress formed in structures at overlying strata, mining‐induced advanced abutment pressure, and the regional in situ stress. Thus, a Two‐Direction Hydrofracturing Technique (TDHT) was proposed to reduce the pressure of the No. 2‐2092 roadway by altering the roof structure in the influenced zones. Compared with the original roadway without fracturing, it is found that the roof to floor convergence has dropped by nearly 47% after fracturing; the displacement of sidewalls has reduced by almost 31%, demonstrating the effectiveness of the proposed method in pressure relief. Results from this study can provide guidance on controlling the large deformation of roadways in deep underground mines.

To explore coal fracture propagation mechanisms, the supercritical CO2 fracturing of coal seams was simulated under true triaxial stress with various injection methods, injection temperatures, and injection flow rates. The spatial–temporal distribution of the fracture propagation and evolution was located by acoustic emission monitoring. The microcosmic action mechanism of supercritical CO2 fracturing to form fractures and its advantages over conventional hydraulic fracturing are discussed in detail. The results suggest that due to the high porosity of coal, CO2 in the local area is subject to multi-phase transitions, which makes the spatial distribution of fractures more discrete and more complex. For coal seam fracturing, supercritical CO2 can reach the fracture tip and penetrate the coal substrate more easily than water. In addition, supercritical CO2 can access smaller channels than that of water, and thus, it tends to induce secondary fractures and connect natural fractures far from the injection site.

A comprehensive understanding of hydraulic fracturing behavior and its impact on regional stress distribution under varying principal stress conditions is essential for preventing dynamic disasters. In this study, true triaxial hydraulic fracturing experiments were conducted using roof sandstone from the Mengcun coal mine. The 3D structure of the hydraulic fractures was reconstructed using CT scanning and numerical simulation to elucidate the effect of intricate geostress conditions on hydraulic fracture propagation. The results indicate that the difference in maximum principal stress plays a crucial role in initiating and propagating hydraulic fractures. Specifically, a greater difference in maximum principal stress increases the likelihood of hydraulic fracture deflection. As this stress difference rises, the angle of hydraulic fracture deflection increases. Additionally, the presence of a hydraulic fracture alters the characteristics of the stress field, leading to stress concentration at the hydraulic fracture tip and stress unloading on both sides. Although the effects of injection rate and rock lithology were not considered in this study, this study remains valuable for optimizing hydraulic fracturing parameters in coal seam roofs.

Airborne dust plumes are difficult to localize in underground mine-face video because the scene is dark, illumination moves with machinery, and dust is confused with lamp bloom, reflective steel, and water-spray aerosol. We present DustVeil, a label-free two-stage system for image-space plume localization. Its software teacher combines background-referenced veiling (C1), local texture decay (C2), and absolute dark-channel response (C3) with a probabilistic soft-OR, then applies glare and chroma gates. The teacher returns a dimensionless response map in [0, 1], a binary plume mask and the corresponding image-area ratio; it does not estimate dust concentration, particle-size distribution, respirable exposure, or hazard categories. Teacher outputs from 342 frames in 114 clips/24 sessions supervise a 0.47 M parameter TinyU-Net. Evaluation uses a 144-image synthetic calibration set and a 72-frame real test set drawn from 72 clips in 18 sessions, with all roles separated at clip and session levels. Thresholds are selected only on synthetic masks and frozen before real scoring. After replacing per-image score normalization with fixed baseline-normal calibration and using reference implementations of the anomaly methods, DustVeil obtains IoU/F1 of 0.366/0.500 and the lowest clean-frame false-positive area (3.7% versus 13.9–59.9%). A separate water-spray set quantifies visual specificity. TinyU-Net runs at 610 FPS for network-only inference and 233 FPS aggregate in the measured six-stream decode-to-mask pipeline; optical flow is excluded from these figures. The validated scope is six fixed visible-light RGB cameras with camera-specific unlabelled calibration at one site, rather than concentration monitoring or camera-disjoint deployment.

Artificial support system takes advantages of self-bearing capacity of surrounding rock mass in roadway support, which is one of the important supporting ideas in modern times. The implementation way of an artificial support system is worthy of deep investigation. In this study, an HLBR hypothesis was proposed with comprehensive consideration of mechanical properties of surrounding rock mass based on the reinforced arch theory and axial variation theory. A model of bearing structure in surrounding rock mass was constructed, and the stress state on the bearing structure was analyzed. It was believed that when the axial ratio (k) of this bearing structure is equal to the lateral stress factor (λ) (which is the optimal axial ratio), the tangential stress on the bearing boundary reaches the minimum and is in uniform distribution. At this moment, the roadway and the supporting structure can make good use of the self-carrying capacity of surrounding rock mass, which is conducive to lowering the stress distribution level of surrounding rock mass. According to prestress diffusion characteristics of bolt, some ways to achieve HLBR were proposed, which were the optimal axial ratio design, difference support and local grouting modification, and finally performance of the original support design in a belt roadway of the mining district IV of a mine in Shanxi Province. A new supporting scheme was provided according to the HLBR hypothesis. In addition, the FLAC3D strain-softening model was modified by C++, which was used to interpret the reasonability of the suggested supporting scheme. The proposed HLBR hypothesis discloses ways to use self-capacity of surrounding rock mass. This study provides a new idea for roadway sectional design and roadway support design, which are beneficial to maintaining the stability of surrounding rock mass in roadways.