Mining Stage Research Articles

Analisis Unsurfaced Road Condition Index Untuk Kualitas Jalan Tambang PT Antareja Mahada Makmur Kalimantan Timur

Overburden stripping is a process of removing overburden to extract the underlying minerals, and is an activity in the early stages of mining. A company that carries out mining activities must carry out stripping activities. The purpose of this study is to analyse the quality of haul roads using the URCI and CBR methods, analyse the obstacles that occur to provide recommendations for improvement, and provide recommendations for the thickness of road layers for overburden haul roads. The research method used is a quantitative method. Road geometry consists of straight road width, bend road width, road slope, superelevation and also crossfall. Based on the test results with the help of dynamic cone penetrometer test, it is known that the CBR value of 6 test points obtained values of 67.5, 42, 59.25, 70.90, 50 and 60, where the limit of good condition of a road based on percent CBR is 55 so that there are 2 roads that are not in good condition. Based on observations using the URCI method with 7 parameters, a value of 65 was obtained for 2 observation locations. Based on the observation results, it is known that in the three rock samples that have been soaked in water for three days, it is known that the material contained in HEX4035 is a material that dissolves quickly in water, resulting in mud. Meanwhile, the material in the mining front of HEX4036 and HEX1440 does not dissolve quickly in water so that the material can be a material for road layers as high as 9 inches for sub base and 7 inches for surface course.

The focal mechanism and field investigations of mining-induced earthquake by super-thick and weak cementation overburden strata fracturing

Mining-induced earthquake (MIE) is a non-natural earthquake induced by mining activities. In Ordos mining area, super-thick and weak cementation overburden strata (STWCS) are common occurrence in Jurassic coal seam overlying strata. To explain and quantify the focal mechanism and roof fracture characteristics of MIE under the STWCS, the surface subsidence, ground borehole televiewer imaging and microseismic monitoring technologies were used to observe the fracturing of STWCS. The relative moment tensor method was also used to explore quantify focal mechanism of MIE. The results show that the development height of rock fractures increases, and the STWCS start to break when the panel below retreats along goafs. During this period, the surface stepped subsidence increases rapidly, and MIEs with magnitude above 2.0 begin to appear. The inversion matrix is constructed with the relative moment tensor method to solve the source mechanism of coal mining microearthquakes. The matrix improves the inversion efficiency and accuracy, thus being suitable for solving the focal mechanism of MIE by roof breaking. When coal seam is mined under the STWCS, the dip angle of focal rupture surface is mainly between 0° and 30°, accounting for about 50% of the total. The seismic source is mainly featured with roof horizontal separation tension and roof rotation compression instability. During mining along goafs, the seismic sources displayed a tendency of upward expansion and the shear slip ruptures were more than that in the solid coal mining stage. The focal mechanism of the MIEs in Shilawusu Coal mine was caused by the primary and periodic tension rupture of the STWCS and shear slip rupture. With the continuous mining of the panel, there is still the possibility of another round of MIEs. The research results provide a reference for the prediction, risk assessment and disaster control of MIEs under extremely thick overburden strata.

Radiological considerations in using uranium mine waste rock for road construction materials.

India's road construction is vital for its infrastructure growth, requiring approximately 20,000 tons of high-quality aggregates per kilometer - materials that are increasingly scarce, leading to higher costs and delays. The industrial sector, a cornerstone of the Indian economy, also struggles with waste management. Earlier studies suggested that industrial waste can be used in road construction materials however, the radiological considerations were not focused. This paper explores the potential of utilizing uranium mine waste rock in road construction materials. In the early stages of uranium mining in India, millions of tons of waste rock are generated and typically discarded, requiring extensive land and costly management. In this study, we assessed the radiological considerations in using waste rocks as road construction material generated from lean uranium ore. For this, a typical layered road design in India is adopted and dose rate were evaluated by QAD-CGGP code calculations and real-world measurements. Results indicate that the external radiation dose by using these waste rock in road construction materials remains below 1mSv/year for the public. The observed dose rate complies the National regulatory agency; Atomic Energy Regulatory Board criteria of 1 mSv/y for the unrestricted use of bulk materials in public domain. This approach not only addresses resource scarcity but also supports environmental sustainability by conserving natural resources, reducing ecological imbalances, and promoting a circular economy.

Multiparameter analysis of small non-flying mammals' response to forest restoration post-bauxite mining in eastern Amazonia.

Bauxite mining has been caused severe changes in the natural ecosystems of the Amazon, but the restoration of these areas is mandatory by federal law in Brazil. The recolonization of fauna is crucial to establishing the ecological functions of recovering forests, and the small nonflying mammals can stand out in this process. Assessing taxonomic and functional diversity parameters, we demonstrated that in the early stages of forest recovery post-bauxite mining, between 6 and 11 years, it is possible to restore approximately 45% of the richness of small non-flying mammal species from the original habitats, that in this case were altered Primary Forests. However, the species richness parameter alone does not reflect the recovery of taxonomic or functional diversity at this stage of forest succession. Although 34.8% of the species composition is shared between the Altered Primary Forest and Forest Areas in Restoration, the abundance distribution per species is less balanced in the latter habitat. The areas did not exhibit significant difference between the functional divergence and functional evenness of ecological functions performed by small nonflying mammals; however, they present differences in terms of the functional richness. We also observed that some functional traits of species, such as larger body mass, are more closely related to the structural characteristics of the Primary Forest, such as high basal area values, litter and percentage forest cover. In the forest recovery areas, we observed a predominance of terrestrial species and those with granivorous and insectivorous diets. Furthermore, our results highlight the importance of applying different taxonomic and functional diversity parameters to understand better the fauna recovery patterns in degraded areas undergoing restoration.

Data lakes: Opportunities, Challenges, Threats and Ways to Mitigate Them

Data lakes, which collect and store huge amounts of structured and unstructured data, are currently one of the most important technological tools. Their structure differs from traditional databases, as they are more flexible and allow organizations to store diverse data in a single repository for further processing and analysis. Their use is advisable in many fields, ranging from business and science to public administration. However, the rapid development of data lakes presents new challenges. The paper presents the key characteristics of data lakes and data warehouses, along with a comparative analysis. It discusses the opportunities for using data lakes, which are related to the diversity of the data stored within them. The main stages of data mining from lakes are presented. The strengths of using data lakes are also described. The paper places great emphasis on analyzing the risks associated with data lakes and proposes ways to mitigate them and the future prospects of data lakes are presented. The paper places significant emphasis on analyzing the risks associated with data lakes and proposes ways to mitigate them. Future perspectives for data lakes are also presented. Working with data lakes is a complex but important process. With the right approach and consideration of the challenges outlined in this paper, organizations will be able to maximize the potential of data lakes and gain competitive advantages.

Research on dust and rockburst control technology for coal mining and mathematical correlation

As many coal mines in China enter the deep mining stage, underground mining is starting to cause some problems, including dust disasters, rockburst, and coal and gas outburst in enclosed sites. In this study, water injection tests were conducted on coal samples using a coal rock multi-field seepage simulation experimental system under geo-stress conditions. Experimental results demonstrate that, as the cycle period increases, permeability exhibits a gradual increase. Areas with high permeability change rates are predominantly observed at the beginning and end of the cycle. The relationship between permeability and the number of cycles is initially linear during the early and middle cycles. However, beyond 30 cycles, the relationship transitions from linear to nonlinear, indicating an accelerated permeability change after a certain cycle threshold. In conclusion, this study addressed and refined the mathematical relationship between volumetric strain and permeability. The findings of this research have significant implications for the prevention of dust emissions and the mitigation of rockburst disasters in the field.

Analysis of work productivity and compatibility of excavation-loading equipment and transport equipment in soil salvaging activities at Katala Hill area of PT. Amman

Abstract PT. Amman Mineral Internasional Tbk in Katala Hill, West Nusa Tenggara Province, Indonesia, is an open-pit mining company producing copper as its main commodity, followed by gold and silver. The initial stage of mining involves soil removal in land clearing activities for reclamation, waste disposal areas, and construction of other infrastructure. In soil salvaging activities, it is essential to understand the influential factors to productivity and the match factor in mechanical equipment, including work efficiency, delay time, cycle time, fill factor, and swell factor. The objective of this study is to determine the productivity and match factor values of the digging-loading equipment and transportation equipment in soil salvaging activities in the Katala Hill area. This study applied the descriptive quantitative method, involving direct field observations of the digging-loading and transportation equipment activities and interviews with mining workers. Based on the results, the actual work efficiency of the digging-loading equipment was 59% and the transportation equipment was 76%, the actual productivity of the digging-loading equipment was 825.00Bcm/h, the transportation equipment productivity was 611.17 Bcm/h, and the compatibility factor value is 0.7408. After increasing the work efficiency of the conveyance by 83%, the conveyance productivity was 667.46 Bcm/h with the match factor increasing to 0.8090.

Applications of Kuz–Ram Models in Mine-to-Mill Integration and Optimization—A Review

The Mine-to-Mill (M2M) approach aims to enhance efficiency and reduce costs in the mineral processing industry by optimizing the mining and processing stages. M2M integrates orebody characterization, blasting, and downstream processes, such as grinding and flotation, demonstrating that material fragmentation directly impacts downstream efficiency. This review studies the development and applications of fragmentation models in M2M integration and optimization, finding that their study is divided into three phases. In the first, the potential of M2M is investigated through simulation models that improve fragmentation in blasting to optimize grinding. The second focuses on the practical application of these models in mines, while the third phase integrates geometallurgical data into mine block models, enhancing production planning and selective ore extraction. The M2M integration has demonstrated significant improvements in plant performance, particularly in increasing grinding efficiency through optimized blast fragmentation. The literature also emphasizes the role of optimizing crushing and grinding conditions through models and circuit adjustments to enhance performance and reducing energy consumption. Geometallurgy plays a crucial role in plant optimization by identifying areas with better processing characteristics and adjusting operating parameters to maximize efficiency. Recent studies have shown how the implementation of integrated models can increase the profitability and sustainability of mining operations.

Data Collection and Preprocessing in Web Usage Mining: Implementation and Analysis

Data collection and data preprocessing are crucial stages in web usage mining, mainly because of the unstructured, diverse, and noisy nature of log data. During data collection, log file datasets are loaded and merged. Effective and comprehensive data preprocessing plays a vital role in ensuring the efficiency and scalability of algorithms used in the pattern discovery phase of web usage mining. This work aims to address these phases by introducing two innovative approaches. The first approach focuses on determining the device used for accessing the web, distinguishing between computers and mobile devices. The second approach aims to determine user sessions and complete paths by utilizing the referrer URL. The entire preprocessing pipeline has been implemented using the C# programming language, and the source code is available on GitHub at the following link: https://github.com/Mohammed91/Web-Usage-Mining.

An aftermath analysis of caving characteristics and movement of overlying strata in fully mechanized longwall gob

The large-scale collapse of overlying strata in the gob directly affect the safe production of coal mines; they are also the major causes of geological disasters, such as ground cracks, surface subsidence, and ground collapse. In this paper, the movement and caved characteristics of overlying strata during coal seam excavation are studied by conducting a physical model experiment. Results show that overlying strata have different movement and caved laws during the initial, intermediate, and later mining stages. During the initial mining stage, overlying strata do not collapse, and the subsidence is extremely small. During the intermediate mining stage, overlying strata cave along the vertical direction, and caved height gradually increases. Large numbers of cavities, abscission layers, and fractures exist between caved strata. The fractured area gradually increases upward, and the subsidence increases considerably. During the later mining stage, overlying strata cave along the horizontal direction. The abscission layers between the caved strata of the central are compacted. The compacted area is surrounded by a fractured area. The compacted and fractured areas increase along the horizontal direction. The subsidence curves exhibit a horizontal variation. Overlying strata evolve from the self-equilibrium stage to the vertical collapse stage, and finally, the horizontal collapse stage. The fractured area changes from a no fractured area to a fractured area, increases vertically, and finally, increases horizontally. The subsidence curve changes from extremely small to large, and finally, changes horizontally.

Improvement of Coal Mining-Induced Subsidence-Affected (MISA) Zone Irregular Boundary Delineation by MT-InSAR Techniques, UAV Photogrammetry, and Field Investigation

Coal mining-induced ground subsidence is a severe hazard that can damage property, infrastructure, and the environment in the vicinity when the deformation is not negligible. The boundary of a mining-induced subsidence-affected zone refers to the area beyond which the ground subsidence is less concerned. Accurately measuring mining-induced ground deformation is essential for delineating the irregular boundary of the impacted area. This study employs multitemporal interferometric synthetic aperture radar (MT-InSAR) techniques, including differential InSAR (DInSAR), InSAR stacking, and interferometric point target analysis (IPTA), to analyze coal mine subsidence and delineate the boundaries of the mining-impacted zones. DInSAR accurately reconstructs, locates, and detects the trend in mining-induced subsidence and correlates well with documented mining operations. The InSAR stacking method maps the spatial variation of the ground’s average line-of-sight (LOS) velocity over the mining area, delineating the boundary of the impacted zone. IPTA analysis combining multilook and single-pixel phases achieves millimeter-level surface measurement above tunnel alignments and measures unevenly distributed deformation fields. This study considers an average of 4 cm per year of surface deformation in the LOS direction as the subsidence threshold value for delineating the boundary of the mining-induced subsidence-affected (MISA) zone during the active coal mining stage. Interestingly, there are twin transportation tunnels near the mining area. The twin tunnels completed before the coal mining activities started were functioning well, but damage was observed after the mining began. Our study reveals the tunnels are located within the InSAR-derived MISA zone, although the tunnels approach the MISA boundary. As direct signs of subsidence, ground fissures have been identified near the tunnels via field investigations and UAV photogrammetry. Furthermore, the derived distribution of ground fissures validates and verifies InSAR measurements. The integrated approach of MT-InSAR, UVA photogrammetry, and field investigation developed in this study can be applied to delineate the irregular boundary of the MISA zone and study the accumulating effects of mining-induced subsidence on the performance of infrastructure in areas proximate to coal mining activities.

Effect of Thick–Hard Main Roof Fracturing on the Spatiotemporal Evolution of Overburden Fractures

Gas gushing and the co-mining of coal and gas outbursts are common disasters in coal mines. The weakening of thick–hard main roof fracturing can effectively alleviate the gas overrun in the initial mining stage. Four numerical simulation schemes were designed to determine the optimal fracturing treatment scheme for the gas overrun problem in the initial mining stage of the 6505# working face in the Huanghou Coal Mine. Compared with the scheme of the non-fracturing main roof, the weakening of the main roof fracturing could alleviate the concentration of advanced abutment stress. The fissure ratio of the overburden was solved by the binary method, and the dominant channels of gas migration and their morphological evolution under different fracturing schemes were obtained. On this basis, the permeability model of “permeability–fissure ratio–fractal dimension” was established. The results show that the overburden fracture network of the horizontal fracturing scheme has a larger fractal dimension, indicating that the overburden fracture under the scheme is more fully developed and more conducive to gas migration. The research results provide valuable reference for the design of the gas extraction scheme.

Spatiotemporal Evolution Mine Groundwater’s Hydrogeochemical Characteristics Under Influence of Mining and Grouting in Gubei Coal Mine, China

Geological conditions or human activities will affect the hydrochemical characteristics and formation mechanism of mine groundwater to varying degrees. The northern part of the Beiyi mining area of Gubei Coal Mine is taken as the research area in this study. Based on the data of 52 groups of limestone water (Taihui water) samples in the primary environment, in the mining stage and after grouting, the spatial and temporal variation trend of the chemical characteristics of Taihui water was studied by means of constant index mathematical statistics, a Piper diagram, total ionic salinity, correlation analysis, the ion ratio method and the saturation index. The purpose of this study is to analyze the influence of special geological structures, mining activities and grouting treatment on the formation process of the chemical characteristics of Taihui water, and to provide a basis for the identification of water inrush sources and the resource utilization of deep mine water in this area. The results show that in the three stages, the order of cation concentration is Na+ + K+ > Ca2+ > Mg2+, and the order of anion concentration is changed from Cl− > SO42− > HCO3− to Cl− > HCO3− > SO42−. The hydrochemical type is the most abundant in the mining stage, and tends to be unified after grouting. The dissolution of carbonate minerals, gypsum, rock salt and silicate minerals; cation exchange; pyrite oxidation; and the mixing of grouting precipitation liquid mainly occur in the limestone water. These effects are enhanced or weakened due to the influence of pumping and drainage and grouting precipitation liquid. The results of this study may be beneficial to the sustainable utilization of deep groundwater resources in other similar mines, and promote the establishment of data management and identification mechanisms of water inrush sources in deep coal seams.

Using geochemical and geophysical data to characterise inter-aquifer connectivity and impacts on shallow aquifers and groundwater dependent ecosystems

Understanding inter-aquifer connectivity within sedimentary basins is crucial for determining how groundwater extraction will impact groundwater resources and groundwater dependent ecosystems (GDEs). Geophysical, geochemical and radioisotope data were combined to understand whether dewatering for open-cut coal mining in Australia's Galilee Basin will be likely to impact groundwater levels in overlying aquifers sustaining the ecologically significant Doongmabulla Springs Complex and Carmichael River. Groundwater salinities (<300 mg/L), measurable 3H (0.43 TU), and activities of radiocarbon a14C (14.1 – 95.3 pMC) and chlorine-36 R36Cl (78.1 × 10−15 – 161 × 10−15) imply that preferential pathways for groundwater flow and recharge occur through the weathered sub-crop of the Galilee Basin sediments. These high permeability zones occur consistently within 5 km of the mine (and further to the south), where strong overlap in major ion and radioisotope compositions indicates significant groundwater connectivity between aquifers. Elevated groundwater HCO3 and F concentrations and heavy fraction hydrocarbons (>100 μg/L C10–C40) also imply deep groundwater in the coal measures discharges into overlying non-coal bearing aquifers, most likely via faults. Since coal mine dewatering commenced, drawdown has spread preferentially southward from the mine, driven by geological heterogeneity including into aquifers that are not targeted by mining. Drawdown is also migrating gradually into shallow aquifers west of the mine, towards GDEs along the Carmichael River valley. Numerical modelling of the mine's groundwater impacts, which was the basis of the mine's approval, did not anticipate this level of drawdown in shallow aquifers at this stage of mining. Mining impacts on shallow groundwater resources and GDEs, including the Doongmabulla springs and the Carmichael River, may have thus been underestimated and require re-evaluation. This study highlights that multiple lines of evidence must be assessed to carefully develop conceptual and numerical models, and to protect groundwater and GDEs.

Enhancing Generalizability in Biomedical Entity Recognition: Self-Attention PCA-CLS Model.

One of the primary tasks in the early stages of data mining involves the identification of entities from biomedical corpora. Traditional approaches relying on robust feature engineering face challenges when learning from available (un-)annotated data using data-driven models like deep learning-based architectures. Despite leveraging large corpora and advanced deep learning models, domain generalization remains an issue. Attention mechanisms are effective in capturing longer sentence dependencies and extracting semantic and syntactic information from limited annotated datasets. To address out-of-vocabulary challenges in biomedical text, the PCA-CLS (Position and Contextual Attention with CNN-LSTM-Softmax) model combines global self-attention and character-level convolutional neural network techniques. The model's performance is evaluated on eight distinct biomedical domain datasets encompassing entities such as genes, drugs, diseases, and species. The PCA-CLS model outperforms several state-of-the-art models, achieving notable F1-scores, including 88.19% on BC2GM, 85.44% on JNLPBA, 90.80% on BC5CDR-chemical, 87.07% on BC5CDR-disease, 89.18% on BC4CHEMD, 88.81% on NCBI, and 91.59% on the s800 dataset.

FBG and BOTDA Based Monitoring of Mine Pressure Under Remaining Coal Pillars Using Physical Modeling.

Strong mine pressure often emerges when the working face of the lower coal seam in a closely spaced coal seam system passes through the remaining coal pillar in the overlying goaf. This study investigates the law of overburden movement and the manifestation of mine pressure during mining under the remaining coal pillar. A physical model measuring 2.5 × 0.2 × 1.503 m is constructed. Fiber Bragg grating sensing technology (FBG) and Brillouin optical time domain analysis technology (BOTDA) are employed in the physical model experiment to monitor the internal strain of the overlying rock as the working face advances. This study determines the laws of overlying rock fracture and working face pressure while mining coal seams beneath the remaining coal pillar. It analyzes the relationship between the pressure at the working face and the strain characteristics of the horizontally distributed optical fiber. A fiber grating characterization method is established for the stress evolution law of overlying rock while passing the remaining coal pillar. The experimental results indicated that the fracture angle of overlying rock gradually decreases during the mining stage through and after the coal pillar. In the mining stage through the coal pillar, the cycle pressure step distance of the working face is reduced by 33.3% compared to the stage after mining through the coal pillar. Initially, the strain pattern of the horizontal optical fiber is unimodal when pressure is first applied to the working face, and it transitions from unimodal to bimodal during periodic pressure. The peak value of fiber Bragg grating compressive strain and the range of influence of advanced support pressure are 3.6 times and 4.8 times, respectively, before passing through the remaining coal pillar. Finally, the accuracy of the FBG characterization method is verified by comparing it to the monitoring curve of the coal seam floor pressure sensor. The research results contribute to applying fiber optic sensing technology in mining physical model experiments.

Study on Coal Seam Roof Failure Based on Optical Fiber Acoustic Sensing and the Parallel Electrical Method

As China enters the stage of deep coal mining, the accidents caused by roof failure pose increasingly serious threats. Current research on roof failure zones often use single methods, but single geophysical data may result in multisolution issues during interpretation. This paper employed similar simulation experiments, exploring the strain failure characteristics and the changes in apparent resistivity caused by stress variations, taking the 11-3106 working face of a mining area as the research object. Through optical fiber strain and apparent resistivity, the locations and degrees of fracture in postmining rock strata were identified. The feasibility of using distributed optical fiber sensing and the parallel electrical method for qualitative and quantitative analysis of mining-induced fractures was verified. The results showed that optical fiber strain increased significantly at the location of rock fracture, with apparent resistivity anomalies rising correspondingly. The peak strain region corresponded well with the region of apparent resistivity anomalies. In a similar simulation with a geometric ratio of 1:100, the height of the caving zone was measured to be 31.65 cm, with a caving-to-mining ratio of 6.33. In the field working face, the caving zone height was 29.47 m, with a caving-to-mining ratio of 6.01, consistent with the actual conditions of the 11-3106 working face.

Study on the heat transfer performance of coaxial casing heat exchanger for medium and deep geothermal energy in cold regions

To accurately assess the heat transfer performance of a medium-depth coaxial casing heat exchanger, this study introduced the concepts of the annual stabilized mining stage and the effective thermal influence distance for each layer of non-homogeneous thermal storage. The study area was stratified into six layers based on the geothermal temperature gradient fitting results. The findings revealed that the maximum injected circulating fluid temperature for the mid-depth coaxial casing geothermal system was 37 °C, with a maximum mass flow rate of 16.67 kg/s. When the injected circulating fluid temperature increased from 2 °C to 25 °C, the duration of the annual stabilized exploitation stage extended from 23 to 26 years. Similarly, increasing the injected circulating fluid mass flow rate from 2.78 kg/s to 16.67 kg/s prolonged the maintenance period in the annual stable mining stage from 22 to 28 years. The study further indicated that the effective thermal influence distance for each layer of thermal storage was significantly impacted by varying injection circulating fluid temperatures. These results offered theoretical insights into the heat transfer performance of medium-depth coaxial casing geothermal systems under both short- and long-term operational conditions.

Investigation of Load Characteristics and Stress-Energy Evolution Laws of Gob-Side Roadways Under Thick and Hard Roofs

The stress environments of gob-side roadways (GSRs) are becoming increasingly complex during deep coal mining under thick and hard roofs. This leads to strong strata behaviors, including roadway floor heave, roof subsidence, and even coal bursts. Among them, coal bursts pose the greatest threat to production safety in coal mines. Coal bursts in a GSR strongly correlate with the load characteristics and stress-energy evolution laws of the roadway. This study analyzes the roof structures of double working faces (DWFs) during the initial weighting stage (IWS) and full mining stage (FMS) of gob-side working faces (GSWFs). This study also explores how varying roof structures affect the stability of GSRs. Three-dimensional roof structure models of DWFs and mechanical models of dynamic and static loads superposition on a GSR throughout the IWS and FMS of a GSWF were developed. An analysis identified the primary stress sources affecting the GSR throughout various mining stages of the GSWF. Subsequently, the principle of “three-load” superposition was developed. A novel method was proposed to quantify the stress state in the GSR surrounding rock across different mining stages of the GSWF. The method quantitatively characterizes the load of the GSR surrounding rock. Based on this, the criterion for judging the burst failure of the roadway was established. Numerical simulations are used to analyze the stress-energy evolution laws of the working face, coal pillar, and GSR surrounding rock during the mining process of the GSWF. These findings offer valuable references for studying and preventing coal bursts in GSRs under equivalent geological situations.

Failure mechanism of severe deformation in gob-side entry rib and unloading-supporting coupling control technology

Given the problem of the solid coal side produces strong mine pressure in the stage of strong mining and lagging dynamic pressure in the gob-side entry retaining (GER). Using the W3233 ventilation roadway in the West-Third mining area as a case study, the research employs numerical simulation, field observation, and engineering analogy. Key findings include: (1) The optimal plan reduces maximum stress on the coal side and shifts it inward, primarily by severing the main roof and alleviating the gangue wall load, offering limited pressure relief on the solid coal rib. (2) When hole-creating depth is too close to the solid coal rib (b = 6 m), it compromises integrity. If the depth exceeds the stress maximum region (b = 10 m), it fails to effectively sever the peak stress area. However, a depth within the stress maximum region (b = 8 m) effectively absorbs and transfers stress, with a buffer area of approximately 3.7 m from the external support area. (3) The length of the hole (l = 2, 4, 6 m) directly affects deformation absorption and pressure relief, while longitudinal row spacing (s = 2.7, 3.6, 4.5 m) has an inverse effect. For optimal results, a hole length of 4 m and a row spacing of 3.6 m are recommended. (4) After 150 days, the new bag pressure regulating system maintains about 40 % of the absorbable deformation space in the LPRH, confirming simulation results. Observations show that external support forces remain stable at around 250 kN, and coal rib displacement is controlled within 350 mm, over 65 % less than similar GER sections with comparable geological conditions. This research introduces a novel technology and methodology for managing large deformations of the solid coal rib in gob-side dynamic pressure roadways, providing significant reference value.