Search Results (8)

Under deep, high-intensity mining conditions, a high mineral pressure develops at the working face, which can easily cause floor heave deformation of the roadway. In this paper, with the geological conditions of Buertai coal mine as the background, through on-site monitoring and numerical simulation, the mechanism of strong dynamic pressure roadway floor heave is clarified and a cooperative control method for roadway floor heave deformation is proposed. The main conclusions are as follows: (1) The overall strength of the floor of this strong dynamic pressure roadway is low, which can easily cause roadway floor heave, and on-site multivariate monitoring of the mine pressure is carried out, which clarifies the evolution law of the mine pressure of the mining roadway and along-the-airway roadway. (2) Combined with FLAC3D numerical simulation software, we analyze the influence of coal seam depth and floor lithology on the stability of the roadway floor and find that both have a significant influence on the stability of the roadway. Under the condition of high-intensity mining, the floor will deteriorate gradually, forming a wide range of floor heave areas. (3) Based on the deformation and damage mechanism of the roadway floor, a synergistic control method of “roof cutting and pressure relief + floor anchor injection” is proposed and various technical parameters are designed. An optimized design scheme is designed for the control of floor heave in Buertai coal mine. Full article

Implementing precise and advanced early warning systems for rock bursts is a crucial approach to maintaining safety during coal mining operations. At present, FEMR data play a key role in monitoring and providing early warnings for rock bursts. Nevertheless, conventional early warning systems are associated with certain limitations, such as a short early warning time and low accuracy of early warning. To enhance the timeliness of early warnings and bolster the safety of coal mines, a novel early warning model has been developed. In this paper, we present a framework for predicting the FEMR signal in deep future and recognizing the rock burst precursor. The framework involves two models, a guided diffusion model with a transformer for FEMR signal super prediction and an auxiliary model for recognizing the rock burst precursor. The framework was applied to the Buertai database, which was recognized as having a rock burst risk. The results demonstrate that the framework can predict 360 h (15 days) of FEMR signal using only 12 h of known signal. If the duration of known data is compressed by adjusting the CWT window length, it becomes possible to predict data over longer future time spans. Additionally, it achieved a maximum recognition accuracy of 98.07%, which realizes the super prediction of rock burst disaster. These characteristics make our framework an attractive approach for rock burst predicting and early warning. Full article

Accurate prediction of methane concentration in mine roadways is crucial for ensuring miner safety and enhancing the economic benefits of mining enterprises in the field of coal mine safety. Taking the Buertai Coal Mine as an example, this study employs laser methane concentration monitoring sensors to conduct precise real-time measurements of methane concentration in coal mine roadways. A prediction model for methane concentration in coal mine roadways, based on an Improved Black Kite Algorithm (IBKA) coupled with Informer-BiLSTM, is proposed. Initially, the traditional Black Kite Algorithm (BKA) is enhanced by introducing Tent chaotic mapping, integrating dynamic convex lens imaging, and adopting a Fraunhofer diffraction search strategy. Experimental results demonstrate that the proposed improvements effectively enhance the algorithm’s performance, resulting in the IBKA exhibiting higher search accuracy, faster convergence speed, and robust practicality. Subsequently, seven hyperparameters in the Informer-BiLSTM prediction model are optimized to further refine the model’s predictive accuracy. Finally, the prediction results of the IBKA-Informer-BiLSTM model are compared with those of six reference models. The research findings indicate that the coupled model achieves Mean Absolute Errors (MAE) of 0.00067624 and 0.0005971 for the training and test sets, respectively, Root Mean Square Errors (RMSE) of 0.00088187 and 0.0008005, and Coefficient of Determination (R²) values of 0.9769 and 0.9589. These results are significantly superior to those of the other compared models. Furthermore, when applied to additional methane concentration datasets from the Buertai Coal Mine roadways, the model demonstrates R² values exceeding 0.95 for both the training and test sets, validating its excellent generalization ability, predictive performance, and potential for practical applications. Full article

The construction of underground reservoirs in coal goaf is a new technology aimed to realize the sustainable development of coal mining-water storage-surface ecology in arid areas of northwest China. The key to the feasibility of this technology is that underground coal mining cannot affect the near-surface aquifer, and the amount of water entering the underground reservoir must meet the needs of the coal mine. Taking Buertai Coal Mine, one of the largest underground coal mines in the world, as an example, this article used similar simulation, numerical simulation and in-situ test methods to study the height of the water-conducting fracture zone of overlying strata and water inflow of underground reservoirs. The results show that, under the repeated mining of the 22- and 42-coal seams, the maximum height of the water-conducting fracture zone is 178 m, and the distance between the near-surface aquifer and the 42 coal is about 240 m, so the mining has little effect on the near-surface aquifer. During the mining period of the 22-coal seam, the groundwater of the Zhidan and Zhiluo Formations was mainly discharged vertically, while the groundwater of the Yanan Formation was mainly a horizontal flow during the period of the 42-coal mining. In this way, the total water inflow of Buertai Coal Mine reaches 500 m³/h, which not only meets the needs of the mine, but also, the rest of the water can irrigate about 98 hectares of farmland nearby. Underground reservoirs in coal goaf could achieve sustainable development of coal mining, groundwater storage and surface ecology in semi-arid areas. Full article

The underground roadway of the Buertai Coal Mine adopts the double-roadway layout. Double-roadway layout mode has a roadway that is affected by repeated mining, called reserved roadways. The reserved roadway is strongly affected by mining, and the strata behaviors appear violently. This paper studies the strata behaviors that occur in auxiliary haulage roadway (AHR) during the mining of panel 42106. By analyzing geological conditions, mining influencing factors, and roadway layout, the mechanism of strong rock behavior has been clarified. Then, based on the theoretical analysis, we put forward the treatment method for the manifestation of strong strata behaviors by using hydraulic fracturing technology to break the key stratum. In this way, the high stress of the surrounding rock can be reduced by forcing the hard roof to be broken. After the application of hydraulic fracturing technology, we monitored the deformation of roadways and the periodic weighting law of the working face. The strength of strata behaviors has significantly weakened, and the application of this technology ensures the safe production of coal mines. Full article

To study the stability control of stope mining roadways below remaining coal pillars, the present study investigates the destabilization mechanism of coal pillars and roadways in sections under the dual action of supporting pressure on the floor of the remaining coal pillar in the overlying coal seam and the mining at the working face of the lower coal seam and clarify the principle of surrounding rock stability control based on theoretical analysis, numerical simulation, and industrial testing. The results yielded the following findings. After the stope mining of the overlying coal seam working face, the stress transfer of the T-shaped remaining coal pillar significantly increased the vertical stress of the lower coal seam. The lateral support pressure generated by the stope mining at the lower coal seam working face further aggravated the stress concentration in the coal, leading to severe compression-shear failure of the surrounding rock. As the sectional coal pillar becomes wider, the roadway gradually avoids the area of peak superimposed support pressure. The vertical stress curve of the sectional coal pillar shifts from single-peaked to asymmetrically double-peaked, and the stress difference between the two roadway ribs and the stress concentration coefficients decrease continuously. A stability control method of long anchor cable reinforcement support is proposed. In-situ industrial testing showed that the surrounding rock deformation was basically stable during the service period of the 42202 stope mining roadway, thus achieving the stability control of the stope mining roadway. Full article

As thick rock partings delay the efficient mining of coal seams and constrain the sustainable development of coal mines, an innovative extraction method for a coal seam with thick rock parting was proposed. The coal seams were divided into different sub-zones according to the thickness of rock parting and then the sub-zones were mined by separately using three mining schemes involving full-seam mining, combined mining using backfill and caving (CMBC), and reducing height mining. Afterwards, the study introduced the basic mechanism and key devices for the CMBC and analysed the working state of the backfill support in detail. Moreover, the method for calculating the length of the backfill zone was proposed to design the length of backfill zone and the influences of four factors (including bulking coefficient) of rock parting on the length of the backfill zone were also explored. By taking the No. 22203 panel, Buertai mine, Inner Mongolia, China as an example, the mined coal resource by using the CMBC extraction method will increase by 1.83 × 10⁶ tons and the recovery ratio will rise from 56.2% to 92.4% compared with mining of the 2-2 upper coal seam alone. Moreover, by applying CMBC, a series of environmental and ecological problems caused by rock parting is reduced, which can improve the environment in mined areas. The research can provide technological guidance for mining panels of a coal seam with a thick rock parting and the disposal thereof under similar conditions. Full article

High-intensity coal mining (large mining height, shallow mining depth, and rapid advancing) frequently causes large-scale ground damage within a short period of time. Understanding mining subsidence under high-intensity mining can provide a basis for mining-induced damage assessment, land remediation in a subsidence area, and ecological reconstruction in vulnerable ecological regions in Western China. In this study, the mining subsidence status of Shendong Coalfield was investigated and analyzed using two-pass differential interferometric synthetic aperture radar (DInSAR) technology based on high-resolution synthetic aperture radar data (RADARSAT-2 precise orbit, multilook fine, 5 m) collected from 20 January 2012 to June 2013. Surface damages in Shendong Coalfield over a period of 504 days under open-pit mining and underground mining were observed. Ground deformation of the high-intensity mining working faces 22201-1/2 in Bu’ertai Mine, Shendong Coalfield was monitored using small baseline subset (SBAS) InSAR technology. (1) DInSAR detected and located 85 ground deformation areas (including ground deformations associated with past-mining activity). The extent of subsidence in Shendong Coalfield presented a progressive increase at an average monthly rate of 13.09 km² from the initial 54.98 km² to 225.20 km², approximately, which accounted for 7% of the total area of Shendong Coalfield; (2) SBAS-InSAR reported that the maximum cumulative subsidence area reached 5.58 km² above the working faces 22201-1/2. The advance speed of ground destruction (7.9 m/day) was nearly equal to that of underground mining (8.1 m/day). Full article