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In order to explore a new method and mode of gently inclined hard roof treatment, the hydraulic fracturing axial roof cutting technology based on abrasive jet is introduced, and the key technical parameters of abrasive jet axial cutting and fracturing are determined based on indoor experiments and field industrial experiments. Taking the mining of working face under the condition of hard roof in Kuangou Coal Mine as the background, the implementation process and the effect of mining process are tested by means of water pressure gauge, drilling peep and observation well water level observation, mi-croseismic monitoring, support fracture monitoring and coal stress monitoring. The research results show that the key technical parameters of slotting and fracturing are mastered in the axial cutting test of abrasive jet. Wherein the kerf depth is 200 m, the kerf length is 300 m, the kerf pressure is 40–50 mpa, the fracturing pressure is 50–55 mpa, and the fracturing time is 20–30 min. After grooving fracturing, the cracks in the roof strata are effectively generated and expanded, which destroys the integrity of the roof, and the fracturing radius is 10–20 m. During the mining period, compared with the tradi-tional blasting technology, the concentrated area of microseismic events was shifted from 80 m in front of the working face to 130 m after the combined treatment of abrasive jet axial roof cutting and blasting, and the microseismic energy release was mainly small energy events. After the application of abrasive jet axial roof cutting and scour prevention technology in hard roof, the periodic weighting step is obviously reduced, the influence range of mining stress and stress concentration coefficient are obviously reduced, the activity intensity and dynamic load effect of surrounding rock are obviously weakened. The research results provide a basis for effective prevention and control of rockburst disasters under the condition of hard roof. [ABSTRACT FROM AUTHOR]

The rockburst phenomenon in excavation endeavours reveals a multitude of complexities and obstacles that significantly impact both the technical and financial dimensions of project execution. Investigating critical rockburst factors in underground excavations is of considerable importance for addressing pivotal safety issues and operational complexities within the field of underground excavation projects. This research proposes an innovative approach based on an expert-based fuzzy cognitive map (FCM) framework, aiming to identify and prioritize the key critical rockburst factors prevalent in underground excavations and tunnelling. A tailored cognitive map of the parameters of problem was constructed, integrating 56 critical and critical factors meticulously curated by a team of seasoned managers, engineers, deputy managers, trainee engineers and assistant managers. The structured cognitive map was meticulously developed, considering the relative weights of the identified critical factors and their intricate interrelationships—all informed by the invaluable insights and expertise of seasoned engineers in the field. Subsequently, the cognitive map underwent a systematic solution process, whereby the causal relationships and influences amongst the identified critical factors were analysed and factored in. The outcomes of the comprehensive analysis unveiled several critical factors: lack of rockburst risk assessments, high in situ stress, presence of rock seams and weak layers, rock quality variations, and geological heterogeneity as the most paramount concerns demanding immediate attention and strategic intervention. By adopting the proposed FCM approach and leveraging the collective expertise of industry professionals, this research offers a robust and systematic framework for comprehensively assessing and addressing the key challenges associated with rockburst events in underground excavations and tunnelling projects, thereby fostering enhanced project performance and efficacy within the field. Highlights: A comprehensive fuzzy cognitive map, based on industry professionals, emphasiSes 56 critical rockburst factors. In rockburst events, the created map considers factor weights, enabling systematic analysis and strategic intervention for project efficacy. Key concerns revealed include the absence of risk assessments, high in situ stress, rock seams, quality variations and geological heterogeneity. Utilising fuzzy cognitive map and industry expertise provides a robust framework for addressing rockburst challenges in underground projects. [ABSTRACT FROM AUTHOR]

With the increase in mining depth and intensity, dynamic disasters such as rockburst in mines are becoming more severe. Deep resource extraction is characterized by a high in-situ stress geological environment, closely associated with geological dynamic disasters. However, there is currently no quantitative analysis method for the correlation between the two. In this study, an elastic energy density calculation method is employed, considering the dissipative effect of the self-weight stress field on the tectonic stress field. The remaining energy, referred to as impact energy, is used to classify the risk of coal seam impact, providing a computational method for rapid assessment of impact risk before mining production. The proposed calculation method is compared with 22 mine impact engineering practices in the literature, showing accurate predictions for 21 mines. Since measuring in-situ stress and coal seam physical and mechanical properties is a preliminary work in coal seam extraction, the comprehensive analysis of these data holds significant research and practical value. [ABSTRACT FROM AUTHOR]

Nowadays, the seismological monitoring system in China is a valuable tool in the rockburst risk evaluation for deep coal mines. In the past, only parameters, like source location and energy, are widely used to estimate the risk level of rockburst. Sometimes, it is effective; however, some other important physical parameters, such as apparent stress drop, static stress drop, P‐wave velocity, and moment tensor, should also be included in order to improve the accuracy of risk assessment. In this study, these parameters are calculated using mine tremor signals recorded in the LW35001 workface of Liangbaosi Coal Mine. These calculations provide an overall identification of periodical stress distribution and rock mass energy‐releasing type under high concentrated stress. Via linear moment tensor inversion procedure, the source mechanism of mine tremors and stress state of the rock mass is determined whether it is risk or not to underground roadway. This comprehensive analysis provides a specific guidance for rockburst prevention for coal mine management, that is, knowing when and where measures must be taken to decrease the risk level or induce the occurrence of rockburst under control. [ABSTRACT FROM AUTHOR]

This study presents a strategy for preventing and controlling rockbursts in deep and vast seams during the mining operation. We analyzed the main factors influencing rockburst by combining the geological structure of the rock mass with field‐collected microseismic monitoring data. Determined the disturbance strain sensitive threshold through mechanical experiments on coal's antidisturbance characteristics, the indoor pull‐out test of the supporting bolt was carried out. Studied the rockburst support technology and the antirockburst capability of the support system based on the energy method. The key governing variables of regional impact risk in the big buried deep coal seam operating face include high tectonic stress, goaf effect, fault, and fault protection coal pillar. The uniaxial compressive strength of the coal sample in the 3308 working face is 15.11 MPa, the antidisturbance strength is 10 MPa. When the extreme stress is 86.03%, the specimen fails; the ultimate failure strength under disturbance is 13 MPa. The support system's antishock ability is analyzed based on its energy absorption, under the premise of ensuring the support quality and support strength, the antiscour ability of 3308 Tailentry support meets the anti‐impact requirements. It is believed that the system offers adequate lateral confining pressure for the internal creep disturbance‐sensitive area, enhancing the area's resistance to disturbance. This is crucial in preventing and managing rockburst incidents. [ABSTRACT FROM AUTHOR]

In addition to the high stress, hard rocks around deep mine entries are also subject to the disturbed stress by mining activities nearby, which increases the risk of rockburst incidents. One preventative measure is the employment of drilling pressure relief (DPR) on hard rocks. This paper analyzes the borehole parameters effects on strength weakening of red sandstone through numerical simulation based on the finite difference method. Input parameters for the numerical simulation were determined by the calibration with laboratory test results. A series of uniaxial compression tests were conducted on red sandstone specimens (100 mm × 50 mm × 50 mm). The mechanical properties and strain energy characteristics of red sandstone were analyzed under different drilling schemes (borehole number, borehole diameter, borehole depth, borehole position, and borehole arrangement angle). The results show that the uniaxial compressive strength (UCS) and strain energy storage capacity of red sandstone decrease by 1.60-39.20% and 35.84-92.77%, respectively after DPR. Moreover, there is a positive correlation between the UCS and elastic strain energy. Further sensitivity analysis of borehole parameters has concluded that the UCS of the specimens is significantly affected by the number of boreholes. In contrast, the borehole diameter prominently affects the strain energy storage capacity. This study verified that DPR has a substantial strength-weakening effect on hard rock, providing a theoretical foundation for further improving the mechanism of DPR in rockburst prevention. [ABSTRACT FROM AUTHOR]

To study the influence of structural planes on rockbursts in the rock surrounding deep tunnels, a series of true triaxial compression tests were carried out on 100 mm × 100 mm × 100 mm red sandstone specimens (including 50 mm diameter circular holes and prefabricated structural planes). The characteristics of the rockburst process and acoustic emission under different structural plane conditions were studied, and the microscopic characteristics of the fracture surface were observed by scanning electron microscope (SEM). The test results show that: (1) The location of the initial damage and the mode and scale of the damage have changed significantly, regardless of the location of the structural plane and its exposure status. The existence of the structural plane will promote the occurrence of rock burst, and the intensity of the structural plane rock burst has also been greatly enhanced, but after the occurrence of the structural plane rock burst, the number and intensity of the rock burst are weakened. The failure process of the specimen with exposed symmetrical structural plane is dominated by slab spalling, and the initial failure position of the unexposed structural plane specimen is the corresponding position of the structural plane. (2) The existence of a structural plane changes the structure of the rock mass, and the transfer path of internal stress in the rock mass changes, It accelerates the overall failure of the specimen, has a significant "weakening effect" on the strength of the specimens, and the final damage of the specimen is more serious.According to the fracture behavior dominated by the structural plane, structural plane rockburst is divided into structural plane–plane pressure/column pressure rockburst and structural plane-buckling rockburst. Note that this failure mode may change with the distance between the structural plane and the hole and the nature of the rock. (3) According to the acoustic emission (AE) events, the existence of structural planes changes the scale of rockburst, the activity of acoustic emission is obviously enhanced, but the number of events is reduced, the generation of microcracks in the rock is reduced, and the proportion of shear cracks is increased. (4) Through SEM observation, the structural plane changes the energy transfer inside the rock mass, showing different micro-crack morphologies. A variety of crack morphologies are observed in the test samples containing structural planes, showing complex crack propagation modes, which means that the internal energy transfer path and scale have changed. The results of this study can enhance the understanding of the influence mechanism of structural planes on the rockburst in deep underground engineering. Highlights: A true triaxial physical simulation test of the rockburst process of surrounding rock with a structural plane near the boundary of a deeply buried tunnel was carried out. The existence of structural planes has significantly changed the development process of rockburst in deep tunnels. The existence of structural planes weakens the structural effect of circular holes in a rock mass. The existence of structural planes promotes the occurrence of rockburst, and an unexposed structural plane significantly increases the intensity of rockburst. [ABSTRACT FROM AUTHOR]

Rock bursts are among the most severe and unpredictable hazards encountered in deep rock engineering, posing substantial threats to both construction safety and project progress. This study provides a comprehensive investigation into how moisture infiltration influences the propensity for rock bursts, aiming to establish new theoretical foundations and practical methods for their prevention. Through the analysis of meticulous laboratory mechanical experiments and sophisticated numerical simulations, we analyzed the variations in the physical and mechanical properties of rocks under different moisture conditions, with a particular focus on strength, brittleness, and energy release characteristics. The findings reveal that moisture infiltration significantly diminishes rock strength and reduces the likelihood of brittle fractures, thereby effectively mitigating the risk of rock bursts. Additionally, further research indicates that in high-moisture environments, the marked reduction in rock burst tendency is attributed to increased rock toughness and the suppression of crack propagation. This study advocates for the implementation of moisture control measures as a pre-treatment strategy for deep rock masses. This innovative approach presents a viable and effective solution to enhance engineering safety and improve construction efficiency, offering a practical method for managing rock burst risks in challenging environments. [ABSTRACT FROM AUTHOR]

Frequent rockburst disasters in deep-buried engineering projects severely impact construction. To explore the influence of axial stress on rockburst in deep-buried tunnels, large-scale true triaxial rockburst experiments were conducted under four different axial stress ratio conditions (ηt, axial loading stress/vertical loading stress) using a self-developed true triaxial loading device under the condition of "pre-loading before excavation". The influence of axial stress on the rockburst process and failure characteristics in deep tunnels was studied using a combination of real-time video monitoring, rockburst debris sieving, and acoustic emission monitoring. The results indicate: (1) all four specimens subjected to different axial stress ratio loading conditions exhibited three stages of macroscopic failure: small particle ejection, flake spalling, and large fragment ejection. Ultimately, "V"-shaped notches appeared on both sides of the tunnel. (2) The failure stress, fragment volume, and fragment size distribution of the rockburst specimens exhibited a clear two-stage failure characteristic with increasing axial stress ratio. In the lower axial stress ratio stage (ηt ≤ 0.7), the increase in the axial stress ratio enhances lateral confinement, thereby increasing the crack initiation strength of the surrounding rock, inhibiting crack formation and propagation, and thus suppressing damage to the surrounding rock of the tunnel. In the higher axial stress ratio stage (ηt > 0.7), the increase in axial stress ratio makes the Poisson effect of the surrounding rock more pronounced, promoting the generation and propagation of cracks along the tunnel axis direction, thereby promoting damage to the surrounding rock. (3) Based on the analysis of acoustic emission parameters (fracture properties), it can be concluded that in the lower axial stress ratio stage (ηt ≤ 0.7), an increase in the axial stress ratio leads to a higher proportion of shear fracture in rockburst damage. Conversely, in the higher axial stress ratio stage (ηt > 0.7), the increase in axial stress ratio gradually reduces the proportion of shear fracture in rockburst damage. [ABSTRACT FROM AUTHOR]

Rockbursts frequently occur in tunneling projects and pose a serious threat to workers and the environment. Therefore, accurate prediction of rockbursts is of great practical significance. Currently, various rockburst prediction methods exist, with static and dynamic indicators playing a key role. This paper analyzes the importance of rockburst prediction methods based on Citespace software. The results indicate that microseismic monitoring, acoustic emission, and machine learning are the most important methods. The paper focuses on four common rockburst prediction methods: empirical methods, microseismic monitoring, acoustic emission, and machine learning, from the perspective of static and dynamic indicators. The performance and application of static and dynamic indicators in the four common prediction methods in recent years are summarized, the limitations of static and dynamic indicators at this stage are discussed, and possible future development directions are proposed. This paper provides the necessary perspective and tools for better understanding the advantages and disadvantages of static and dynamic indicators in the four rockburst prediction methods. [ABSTRACT FROM AUTHOR]

To investigate the influence of joints on the rockburst process in the surrounding rock of deep tunnels, a free-face true-triaxial test was conducted on the rockburst of the jointed surrounding rock of a tunnel. The rockburst ejection failure process (i.e., failure mode, rock strength, and deformation characteristics), rockburst debris characteristics, and acoustic emission evolution characteristics of red sandstone specimens under different joint conditions were investigated. The experimental results indicate that the failure modes of red sandstone specimens with a joint condition perpendicular to the tunnel direction generally exhibit 'internal shear and external splitting', which can suppress the occurrence of rockbursts, whereas the failure mode of red sandstone specimens with a joint condition parallel to the tunnel direction is mainly shear fracture, which can also promote the occurrence of rockbursts. The variation trend of the peak strength and the joint angle of the specimen exhibits a 'U' type shape, and the debris pertaining to the joint specimen's rockburst exhibits fractal characteristics. With the increase of the joint inclination angle, the fragment's ejection kinetic energy exhibits a trend of decreasing first and subsequently increasing. There are significant differences in the total number pertaining to impacts of acoustic emissions during rockburst under different joint conditions. The distribution range pertaining to the dominant frequency signal of the acoustic emission signal at the time of rockburst is mainly a low-frequency signal, and the intermediate-frequency, high-frequency, and ultra-high-frequency signals also exist, thus indicating that the rockburst damage exhibits strong complexity. Finally, the strain rockburst mechanism of jointed rock is significantly different from that of jointless intact rock. The rockburst mechanism is mainly divided into two typologies: shear fracture and slab buckling-shear fracture. The research results contribute to a deeper understanding of the underlying mechanisms of rockburst disasters in jointed rock formations. Highlights: Successfully performed a free-face true-triaxial rockburst test in the jointed surrounding rock of a tunnel. The presence of different joints under true-triaxial conditions significantly alters the mechanism of strain-induced rockburst. Joints perpendicular to the tunnel direction reduce the occurrence of rockbursts, whereas joints parallel to the tunnel direction promote the occurrence of rockbursts. With the increase of the joint inclination angle, the fragments' ejection kinetic energy exhibits a trend of decreasing first and subsequently increasing, where the joint inclination angle of 30° is the transition's inflection point. [ABSTRACT FROM AUTHOR]

Based on the polycrystalline modelling system and basic theory of 3D discrete element, a 3D polycrystalline discrete element method (3DPDEM) that can indicate the microstructure of heterogeneous rocks was proposed to simulate the catastrophe process of rockburst. Interface program of NEPER-DEM data was developed to automatically output a simulation fine model of crystal scale (CSFM) for the consideration of mineral grain composition. The evolution characteristics of rockburst considering grain size and excavation under the condition of true triaxial with one-sided unloading was investigated. The findings show that the catastrophe process of rockburst in coarse-grained sample can be classified into: grain ejection, rock spalling into plate, rock shearing into fragment, and rock fragment ejection. The fine and medium grained sample have undergone processes such as small grain ejection, spalling, buckling, loosening, etc. The peak stress of coarse-grained sample is 28.19% and 10.05% higher than that of fine and medium-grained sample, respectively. The grain size has an important influence on the rockburst proneness, and the coarser the grain size, the stronger the rockburst proneness. The acoustic emission count of coarse-grained sample is 1.27 and 1.16 times higher than that of fine and medium-grained sample, respectively. The fine and medium-grained sample demonstrate rupture-loosening type rockburst, and the coarse-grained sample demonstrate burst-ejection type rockburst under the same loading and unloading path. The shape of rock slice (rock block) formed by the rockburst in the simulation (coarse-grained) and the actual engineering is similar, and the effect of CSFM the engineering scale problem is achieved. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Dalian University of Technology / Dalian Ligong Daxue Xuebao is the property of Journal of Dalian University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Effective monitoring techniques and equipment are essential for the prevention and control of coal and rock dynamic disasters such as rockburst. Based on the fact that there is charge generation during deformation and rupture of coal rock body and the charge signals contain a large amount of information about the mechanical process of deformation and rupture of coal rock, the rockburst charge sensing monitoring technology has been formed. In order to improve the charge sensing technology for monitoring and early warning of rockburst disasters, this paper develops a new generation of portable coal rock charge monitoring instrument on the basis of the original instrument and carries out laboratory and underground field application. The primary advancement involves enhancing the external structure of the sensor and increasing the charge sensing area, which can more comprehensively capture the charge signals from the loaded rupture of the coal rock body. The overall structure of the data acquisition instrument has been improved, the monitoring channels have been increased, and the function of displaying the monitoring data curve has been added, so that the coal and rock body force status can be grasped in time. The results of the experimental study show that the abnormal charge signals can be monitored during the rupture process of rock samples under loading, and the monitored charge signals are in good agreement with the sudden change of stress in the rock samples and the formation of crack extension. There is a precursor charge signal before the stress mutation, and the larger the loading rate is, the earlier the precursor charge signal appears. The charge monitoring instrument can monitor the charge signal of the coal seam roadway under strong mining pressure. In the zone of elevated overburden pressure, the amount of induced charge is large, and anomalously high value charge signals can be monitored when a coal shot occurs. The change trend of the charge at different measuring points of strike and inclination has a good consistency with the distribution of overrunning support pressure and lateral support pressure, which can reflect the stress distribution and the degree of stress concentration of the coal body through the size and location of the charge, foster early warning and analysis of rockburst, and provide target guidance for the prevention and control of rockburst. [ABSTRACT FROM AUTHOR]

Supporting and controlling rockburst hazards is a great challenge for deep rock engineering. A new cable, the negative Poisson's ratio (NPR) cable, exhibits excellent mechanical properties, including high energy absorption and resilience to impacts. To investigate its control effect on rockburst, a series of true triaxial strainburst experiments were conducted on sandstone specimens under different anchoring conditions (no support, ordinary support, NPR cable support). The model NPR cables were developed based on similar principles. In addition, the acoustic emission response and fragmentation characteristics were analysed. The experimental results indicate that the NPR cables are capable of co-deforming with the rock and absorbing energy, increasing rock strength and promoting internal rock tensile fracture. The rapid response of the NPR cables during rockbursts provided effective support, exerted better impact resistance and significantly reduced the mass and fractal dimension of the ejected fragments. Thus, NPR cables can reduce kinetic energy release and effectively control rockburst hazards compared to ordinary cables. The aim of this paper is to provide a reference for the design of rockburst support in engineering. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Geology & Exploration is the property of Xian Research Institute of China Coal Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rupture of super-thick key strata is a crucial factor in triggering mine dynamic disasters. Investigating the impact of their non-uniform thickness on mining-induced stress environments and rupture dynamic loads, and further revealing the mechanism of dynamic and static loading on rock burst pressure, is the theoretical foundation for predicting rock burst risks and disaster prevention and control. This paper investigates the non-uniformly thick “bow-shaped” super-thick key strata in the Binchang mining area of Shaanxi. Through comprehensive theoretical analysis and numerical simulation, it analyzes the mechanical principle of abnormal stress concentration in the coal rock mass beneath the “bow-shaped” super-thick key strata, clarifies the influence of the “bow-shaped” morphology on the rupture characteristics of the super-thick key strata and reveals the mechanism of dynamic and static load superposition in the area beneath the “bow-shaped” formation, leading to rock bursts. Based on the study above, a method for predicting the disaster risks caused by the rupture of “bow-shaped” super-thick key strata is proposed. The results show that in the convex area under the “bow-shaped” formation of the super-thick key strata, the high stress is exceptionally concentrated, increasing the coal rock body stress by an additional 22.1 MPa, with an increase rate of up to 56%, which is the fundamental reason for the high static load formation in the underlying coal-rock body. At the same time, the principal stress in the concave area of the “bow-shaped” formation concentrates and undergoes significant deformation, increasing the risk of strong dynamic loads due to rupture. Under the combined action of dynamic and static loads in the non-uniformly thick “bow-shaped” super-thick key strata, the rock bursts are likely to occur in the pillar and roadway areas. The proposed method for predicting the disaster risks due to the rupture of “bow-shaped” super-thick key strata effectively guides the disaster prevention and control in high-risk mining areas prone to rock bursts. Additionally, the distributed fiber optic field measurement results validate the intrinsic connection between the rupture of super-thick key strata and the generation of dynamic loads.

Abstract With the increase in mining depth and intensity, dynamic disasters such as rockburst in mines are becoming more severe. Deep resource extraction is characterized by a high in-situ stress geological environment, closely associated with geological dynamic disasters. However, there is currently no quantitative analysis method for the correlation between the two. In this study, an elastic energy density calculation method is employed, considering the dissipative effect of the self-weight stress field on the tectonic stress field. The remaining energy, referred to as impact energy, is used to classify the risk of coal seam impact, providing a computational method for rapid assessment of impact risk before mining production. The proposed calculation method is compared with 22 mine impact engineering practices in the literature, showing accurate predictions for 21 mines. Since measuring in-situ stress and coal seam physical and mechanical properties is a preliminary work in coal seam extraction, the comprehensive analysis of these data holds significant research and practical value.

Abstract This study presents a strategy for preventing and controlling rockbursts in deep and vast seams during the mining operation. We analyzed the main factors influencing rockburst by combining the geological structure of the rock mass with field‐collected microseismic monitoring data. Determined the disturbance strain sensitive threshold through mechanical experiments on coal's antidisturbance characteristics, the indoor pull‐out test of the supporting bolt was carried out. Studied the rockburst support technology and the antirockburst capability of the support system based on the energy method. The key governing variables of regional impact risk in the big buried deep coal seam operating face include high tectonic stress, goaf effect, fault, and fault protection coal pillar. The uniaxial compressive strength of the coal sample in the 3308 working face is 15.11 MPa, the antidisturbance strength is 10 MPa. When the extreme stress is 86.03%, the specimen fails; the ultimate failure strength under disturbance is 13 MPa. The support system's antishock ability is analyzed based on its energy absorption, under the premise of ensuring the support quality and support strength, the antiscour ability of 3308 Tailentry support meets the anti‐impact requirements. It is believed that the system offers adequate lateral confining pressure for the internal creep disturbance‐sensitive area, enhancing the area's resistance to disturbance. This is crucial in preventing and managing rockburst incidents.

Abstract Nowadays, the seismological monitoring system in China is a valuable tool in the rockburst risk evaluation for deep coal mines. In the past, only parameters, like source location and energy, are widely used to estimate the risk level of rockburst. Sometimes, it is effective; however, some other important physical parameters, such as apparent stress drop, static stress drop, P‐wave velocity, and moment tensor, should also be included in order to improve the accuracy of risk assessment. In this study, these parameters are calculated using mine tremor signals recorded in the LW35001 workface of Liangbaosi Coal Mine. These calculations provide an overall identification of periodical stress distribution and rock mass energy‐releasing type under high concentrated stress. Via linear moment tensor inversion procedure, the source mechanism of mine tremors and stress state of the rock mass is determined whether it is risk or not to underground roadway. This comprehensive analysis provides a specific guidance for rockburst prevention for coal mine management, that is, knowing when and where measures must be taken to decrease the risk level or induce the occurrence of rockburst under control.

How to achieve intelligent, safe and efficient mining of rockburst coal seams is a major engineering and technical challenge facing deep coal mining. The core connotation of this issue lies in the intelligent, unmanned, and inherently safe mining of coal seams with rockburst. Through accurate perception and intelligent early warning of coal and rock burst risks, as well as self-adaptation and self-optimization of mining engineering, intelligent anti-burst and mining control technologies are formed to achieve a fundamental shift from engineering-induced disasters to engineering-prevented and mitigated disasters. By implementing measures such as mining source design, roof area fracturing, localized targeted management, and strengthening roadway support, a low-stress environment and safe roadway space are created for the safe and efficient mining of coal seams with rock burst. On this basis, a big data analysis software platform that integrates static geological, dynamic monitoring, working conditions, personnel positioning, production organization, historical data and other information, as well as an intelligent mining control system that integrates impact pressure decision-making information, has been developed. The anti-impact information source has been transformed into an intelligent mining control source, forming a new flexible intelligent mining model of "low pressure fast pushing, medium pressure slow mining, and high pressure production stop". Field application shows that in the intelligent anti-impact and control mining area, the degree of mine pressure in working face and roadway is smaller,, and the energy release of coal and rock is more stable, which is conducive to the reasonable release of impact mine production capacity.

The surrounding rock of the impact hazard roadway is often disturbed by external dynamic loads, which often leads to the occurrence of impact ground pressure. In order to explore the anti impact and pressure relief effects of large-diameter pre relief boreholes in coal seams under dynamic load disturbance conditions, a comprehensive method including theoretical analysis, laboratory experiments, and numerical simulations was used to study the dynamic load response law and limit of coal seam anti impact and pressure relief boreholes. The results indicate that the coal body in the pressure relief zone of large-diameter drilling forms a weak structure, increases the ability to attenuate dynamic loads, and reduces the possibility of impact. Under low dynamic load disturbance, the expansion of pores and cracks, and the cumulative acoustic emission events show an upward trend with the increase of disturbance period; Under higher dynamic load disturbances, the degree of damage and rupture of coal samples in boreholes intensifies, and acoustic emission events are mainly high-energy. As the dynamic load level and disturbance period increase, the distance between the stress concentration zone, elastic high-energy zone and the borehole shortens, the influence range increases, the rock movement trend strengthens, and the degree of elastic energy accumulation increases. Under low dynamic load level disturbances, drilling plays a role in energy dissipation, pressure relief, and anti-collision, which can maintain the stability of the surrounding rock. However, under high-energy dynamic load disturbances, the anti-collision of large-diameter drilling fails, and the drilling wall is prone to dynamic instability and damage, causing instability of the surrounding rock. Overall, large-diameter pressure relief boreholes have weakened structures that can dissipate energy, reduce impact, and lower the degree of dynamic load disturbance. However, under high-energy and high-frequency dynamic load disturbances, the movement trend of the surrounding rock of the pressure relief borehole increases, the degree of fracture response is severe, and the anti impact effectiveness is limited.

Microseismic monitoring data plays a crucial role in predicting and warning dynamic hazards such as coal mine rockburst. Utilizing historical microseismic monitoring data to forecast the evolution characteristics of future microseismic events is an effective approach to enhance the timeliness and accuracy of rockburst prediction and early warning. However, due to the non-stationary nature of microseismic data, conventional time series prediction methods often struggle to achieve accurate forecasts. To address this issue, this paper proposes a microseismic time series prediction method based on the combination of modal decomposition technique and deep learning methods. Firstly, the adaptive noise complete ensemble empirical mode decomposition (CEEMDAN) is employed to decompose the microseismic data into multiple intrinsic mode sequences. Subsequently, the decomposed sequences are reconstructed into high-frequency, low-frequency, and trend sequences using sample entropy. Furthermore, the variable mode decomposition (VMD) method is utilized to further decompose the high-frequency and low-frequency sequences into multiple new intrinsic mode sequences, which serve as the multivariate feature time series of microseismic data. Finally, a convolutional neural network (CNN) and long short-term memory network (LSTM) combined microseismic time series prediction model is established, with the microseismic multivariate feature time series within a certain time window and historical microseismic data as inputs, and the next moment microseismic monitoring data as output. The Bayesian optimization method is employed to optimize the hyperparameters of the model, aiming to improve the accuracy of microseismic prediction. Based on the microseismic monitoring data from the multiple working faces of the Xinjulong coal mine, the proposed method is applied to predict the daily maximum energy, daily average energy, and daily frequency of microseismic events, and a series of comparative experiments are conducted on the prediction of daily maximum energy data. The results show that the proposed method can effectively predict the evolution trend of microseismic events, with small errors between the predicted results and actual monitoring values. It demonstrates a good predictive performance and generalization ability.

Microseismic source location is crucial for the early warning of rockburst risks. However, the conventional methods face challenges in terms of the microseismic wave velocity and arrival time accuracy. Intelligent techniques, such as the full convolutional neural network (FCNN), can capture spatial information but struggle with complex microseismic sequence. Combining the FCNN with the long short-term memory (LSTM) network enables better time-series signal classification by integrating multi-scale information and is therefore suitable for waveform location. The LSTM-FCNN model does not require extensive data preprocessing and it simplifies the microseismic source location through feature extraction. In this study, we utilized the LSTM-FCNN as a regression learning model to locate the seismic focus. Initially, the method of short-time-average/long-time-average (STA/LTA) arrival time picking was employed to augment spatiotemporal information. Subsequently, oversampling the on-site data was performed to address the issue of data imbalance, and finally, the performance of LSTM-FCNN was tested. Meanwhile, we compared the LSTM-FCNN model with previous deep-learning models. Our results demonstrated remarkable location capabilities with a mean absolute error (MAE) of only 7.16 m. The model can realize swift training and high accuracy, thereby significantly improving risk warning of rockbursts.

Rockburst has always been a challenge for the safe construction of deep underground engineering. This study investigated the rockburst characteristics in highly-stressed D-shape tunnels under impact loads from rock blasting and other mining-related dynamics disturbances. The biaxial Hopkinson pressure bar was utilized to apply varying biaxial prestress and the same impact loads to cube specimens with D-shape hole. High-speed camera and digital image correlation (DIC) were used to capture the failure process and strain field of specimen. The test results demonstrate that the D-shape hole specimen experience rockburst under coupled static stress and impact load. Under this circumstance, the rockburst mechanism of the D-shaped hole specimens involves spalling in sidewall induced by impact load, indicating dynamic tensile failure. The high static prestress provides the initial stress field, while the impact load disrupts the stress equilibrium, result in the stress or strain concentration in the sidewall of the D-shape hole, inducing rockburst. Moreover, the rockburst process can be divided into (1) calm stage, (2) crack initiation, propagation, and coalesce stage, (3) spalling stage and (4) rock fragments ejection stage. Impact load triggers rockburst occurrence, while vertical stress further determines the rockburst characteristics. The influence range and magnitude of strain concentration zone and displacement deformation of the tunnel surrounding rock increases with increasing vertical stress, thus inducing more severe rockburst.

Abstract Practical experience in coal mines has suggested that establishing a loose and soft structure in the surrounding rock of roadways can play a role in wave attenuation, energy absorption and erosion prevention, which is conducive to the prevention of and reduction in the severity of rockburst disasters in coal mines. The scale parameters of soft structures includes two aspects: the size and the fracture degree of soft structures. The FLAC3D numerical simulation software was used to study the failure characteristics of roadways with different impact positions (roof impact, side impact) and different impact energies (104, 105, 106, and 107 J). The stress reduction rates of soft structures with different sizes and fracture degrees were calculated. Based on the stress reduction rate of the soft structure, the energy absorption effect of the soft structure around the roadway was obtained as a logarithmic function of the soft structure size, which is a power function related to its fracture degree, and the intersection range of the two curves was fitted. The stress reduction rate was 30% when the soft structure size of the surrounding rock of the roadway was 10–15 m and the fracture degree was represented by 30–40% of the coal strength, which was the most reasonable range of scale parameters. The research conclusions provide a parametric basis for improving the theory and practice of rockburst prevention and support in coal mine roadways.

Abstract The Qinling water conveyance tunnel has a large buried depth and high in-situ stress level, and rockburst disasters frequently occurred during excavation. In order to find out the mechanical mechanism of rockburst, the research work in this paper is as follows: (1) In-situ three-dimensional hydraulic fracturing method was used to measure the in-situ stress of the deep buried tunnel crossing the ridge. (2) Based on the measured in-situ stress results, the stress distribution characteristics of the tunnel crossing the ridge were obtained by the multiple linear regression method, and the rockburst tendency during construction was predicted. (3) A three-dimensional numerical model of tunnel excavation was established to analyze the dynamic adjustment characteristics of the surrounding rock stress and elastic strain energy during TBM excavation, and to clarify the mechanical mechanism of rockburst. The research results show that the maximum principal stress of the deep-buried tunnel crossing the ridge of Qinling is 40–66 MPa, which belongs to extremely high in-situ stress level, and medium-strong rockburst may occur during excavation. In the process of TBM excavation, the stress of the surrounding rock in the range of 2.6 times the diameter of the tunnel before and after the working face is adjusted violently, and the concentrated zones after the stress redistribution are mainly distributed in the arch roof and arch bottom, and the stress concentration coefficient can reach 2.06. The arch roof, arch waist, and arch bottom are susceptible to immediate rockburst due to stress transient unloading at the moment of excavation. After the elastic strain energy of the surrounding rock at the arch roof and the arch bottom is released and accumulated, it is easy to cause time delayed rockburst, and the depth of the rockburst pit can reach 3.5 m, which is consistent with the rockburst phenomenon in the field.

Rockburst disaster has become a major safety hazard for deep cavern construction worldwide. Using the new true triaxial rockburst test system, an indoor physical simulation test of “single face lateral unloading-three direction and five faces stress-vertical continuous loading” under different intermediate principal stresses was conducted. The ejection failure process, failure mode, acoustic emission characteristics, fragment characteristics and ejection kinetic energy of rock samples under different intermediate principal stresses were compared and analyzed. Based on the three-dimensional discrete element theory and the polycrystalline modeling technique (randomly generated Voronoi mineral grains), the entire process of rockburst inoculation-occurrence-development-failure as well as the energy evolution characteristics under true triaxial single face unloading conditions were studied. The results indicate that the ejection failure process of rockburst under different intermediate principal stresses can be summarized as four stages: grains ejection, rock spalling into plates, rock shearing into fragments, and rock fragments ejection. Among them, the rock spalling into plates is an inevitable failure phenomenon in the process of rockburst. The failure modes of free face of rock samples have similar multi-zone failure characteristics. That is, the splitting cracks dominated by tensile failure are generated near the free face, and the penetrating shear cracks dominated by shear failure are generated away from the free face. The evolution process of AE hits can be divided into four stages: relatively stable, rapid rising, overall failure stage and quiet period. As the intermediate principal stress increases, the ejection kinetic energy of the fragments increases. Rockburst fragments is mostly coarse-grained, medium-grained, and fine-grained fragments. With the increase of intermediate principal stress, the mass of fine particles is basically unchanged, while the mass of fine, medium and coarse particles shows a steady increase trend. The entire process of rockburst inoculation−occurrence−development−failure is successfully simulated using the crystal scale fine model (CSFM) considering the grain mineral composition. The variation trend of the stress-strain curve of the rock sample is basically consistent with the indoor test results and the curve is in good agreement. The evolution curve of elastic strain energy can be roughly divided into the early growth rate increasing stage, the approximate linear growth stage, the growth rate decreasing stage during the yield platform period and the post-peak sharp decline stage.

It is of great significance to accurately identify the rockburst hazard areas and give the hazard level and its evolution law for rockburst prevention and control. In this study, the method combining deformation localization with multivariate geophysical indicators spatial scanning is used to explore the precursor characteristics of microseismic in the area of high-energy microseismic events and track the dynamic evolution process of rockburst hazard areas. Based on the principle of deformation localization, the gradient significance indicator is used to identify the deformation localization areas and delineate the hazard area. The sliding window scanning method is used to study the spatial distribution characteristics of physical indicators such as b value, A(b) value and S value in the deformation localization areas. The b value, A(b) value, S value, ∆F and A(t) value corresponding to the high-energy microseismic events identified by the gradient significance index during excavation are used as the threshold values for classifying the rockbrust hazard level during the mining operation. The Bayesian network method is used to analyze the effectiveness of each physical indicator in predicting the hazard areas, and a comprehensive predicting hazard areas model is constructed to calculate the weight of physical indicators and obtain the comprehensive predicting indicators. The 513 working face is analyzed as an example. The results show that the geophysical indicators can identify the microseismic gathering signal and assess the hazard areas. Three microseismic events gathering areas are determined according to the measured data of 513 working face. The spatial scanning results of physical indicators and the gathering areas of microseismic data have the synchronization characteristics. When some high-energy microseismic events occur, the physical indicator value of the area is higher than the rockburst hazard threshold, and the hazard areas identified by the physical indicator spatial scanning is basically consistent with the gathering areas of microseismic data. The integrated prediction model is used to predict the hazard area during the mining period of the working face. The results show that the rockburst hazard events mostly occur in the strong high hazard areas predicted by the integrated prediction indicator. With the superposition of microseismic data during the mining period, the high rockburst hazard areas is further concentrated, and the overlap degree with the high hazard event location is higher. The prediction efficiency of the integrated prediction indicator is generally higher than that of single physical indicator, which significantly enhances the ability to accurately predict the rockburst hazard areas.

Rockburst are often encountered in tunnel construction due to the complex geological conditions. To study the influence of unloading rate on rockburst, gneiss rockburst experiments were conducted under three groups of unloading rates. A high-speed photography system and acoustic emission (AE) system were used to monitor the entire process of rockburst process in real-time. The results show that the intensity of gneiss rockburst decreases with decrease of unloading rate, which is manifested as the reduction of AE energy and fragments ejection velocity. The mechanisms are proposed to explain this effect: (i) The reduction of unloading rate changes the crack propagation mechanism in the process of rockburst. This makes the rockbursts change from the tensile failure mechanism at high unloading rate to the tension-shear mixed failure mechanism at low unloading rate, and more energy released in the form of shear crack propagation. Then, less strain energy is converted into kinetic energy of fragments ejection. (ii) Less plate cracking degree of gneiss has taken shape due to decrease of unloading rate, resulting in the destruction of rockburst incubation process. The enlightenments of reducing the unloading rate for the project are also described quantitatively. The rockburst magnitude is reduced from the medium magnitude at the unloading rate of 0.1 MPa/s to the slight magnitude at the unloading rate of 0.025 MPa/s, which was judged by the ejection velocity.

Practical experience in coal mines has suggested that establishing a loose and soft structure in the surrounding rock of roadways can play a role in wave attenuation, energy absorption and erosion prevention, which is conducive to the prevention of and reduction in the severity of rockburst disasters in coal mines. The scale parameters of soft structures includes two aspects: the size and the fracture degree of soft structures. The FLAC3D numerical simulation software was used to study the failure characteristics of roadways with different impact positions (roof impact, side impact) and different impact energies (104, 105, 106, and 107 J). The stress reduction rates of soft structures with different sizes and fracture degrees were calculated. Based on the stress reduction rate of the soft structure, the energy absorption effect of the soft structure around the roadway was obtained as a logarithmic function of the soft structure size, which is a power function related to its fracture degree, and the intersection range of the two curves was fitted. The stress reduction rate was 30% when the soft structure size of the surrounding rock of the roadway was 10–15 m and the fracture degree was represented by 30–40% of the coal strength, which was the most reasonable range of scale parameters. The research conclusions provide a parametric basis for improving the theory and practice of rockburst prevention and support in coal mine roadways. [ABSTRACT FROM AUTHOR]

The Qinling water conveyance tunnel has a large buried depth and high in-situ stress level, and rockburst disasters frequently occurred during excavation. In order to find out the mechanical mechanism of rockburst, the research work in this paper is as follows: (1) In-situ three-dimensional hydraulic fracturing method was used to measure the in-situ stress of the deep buried tunnel crossing the ridge. (2) Based on the measured in-situ stress results, the stress distribution characteristics of the tunnel crossing the ridge were obtained by the multiple linear regression method, and the rockburst tendency during construction was predicted. (3) A three-dimensional numerical model of tunnel excavation was established to analyze the dynamic adjustment characteristics of the surrounding rock stress and elastic strain energy during TBM excavation, and to clarify the mechanical mechanism of rockburst. The research results show that the maximum principal stress of the deep-buried tunnel crossing the ridge of Qinling is 40–66 MPa, which belongs to extremely high in-situ stress level, and medium-strong rockburst may occur during excavation. In the process of TBM excavation, the stress of the surrounding rock in the range of 2.6 times the diameter of the tunnel before and after the working face is adjusted violently, and the concentrated zones after the stress redistribution are mainly distributed in the arch roof and arch bottom, and the stress concentration coefficient can reach 2.06. The arch roof, arch waist, and arch bottom are susceptible to immediate rockburst due to stress transient unloading at the moment of excavation. After the elastic strain energy of the surrounding rock at the arch roof and the arch bottom is released and accumulated, it is easy to cause time delayed rockburst, and the depth of the rockburst pit can reach 3.5 m, which is consistent with the rockburst phenomenon in the field. [ABSTRACT FROM AUTHOR]

The utilization of machine learning (ML) for rockburst assessment is hindered by an incomplete problem formalization in prior studies, which have focused more on predictive accuracy and less on factors such as explainability and uncertainty quantification. Despite achieving commendable accuracies, practitioners remain apprehensive about real-time implementation due to concerns surrounding transparency and validity, particularly when dealing with challenging or unfamiliar rock samples. This uncertainty may result in arbitrary predictions which are mostly incorrect. Establishing trust in ML applications, particularly in critical domains like rockburst assessment, requires models to provide transparent reasoning, communicate uncertainty, and exercise caution when making assertive predictions with unfamiliar data. This paper addresses these concerns by introducing a novel framework that combines interpretable ML techniques specifically Shapley additive explanation (SHAP), with adaptive conformal prediction (CP), built atop extreme gradient boosting to establish a transparent and reliable predictive framework. The validity of the proposed framework was rigorously assessed using conformal metrics, including marginal coverage, conditional coverage, and average prediction set size. Additionally, the SHAP technique was employed to elucidate explanations for predictions flagged as unreliable through CP. The results justify the framework's high effectiveness in generating valid predictions for rockburst grades, concurrently providing corresponding confidence levels and insights into the underlying mechanisms that drive these predictions. The proposed framework facilitates the identification of unreliable predictions, ensuring that only reliable predictions inform decision-making. This not only enhances user confidence in the predictive model but also contributes to the overall safety of underground engineering projects. Highlights: A framework that combines conformal prediction and interpretable machine learning for rockburst assessment is proposed. The proposed framework guarantees marginal coverage and, in most cases, conditional coverage on the test dataset. The conformal prediction identifies several predictions as unreliable, which require expert verification for decision-making purposes. Analysis using Shapley additive explanation revealed that the most important input feature for predicting rockbursts is wet condition. [ABSTRACT FROM AUTHOR]

Structural plane plays an important role in affecting the rockburst, especially when it is subjected to an external dynamic disturbance. To investigate the influence of weak dynamic disturbances on a structural rockburst, a series of rockburst tests were conducted using a true triaxial rockburst testing machine enhanced by a video monitoring system. The granite specimens were thin squares (200 mm × 200 mm × 30 mm) with a circular hole (diameter of 50 mm) in the center. These specimens were used to simulate the occurrence of structural rockbursts in tunnels. The structural rockburst process and the corresponding acoustic emission (AE) and energy release were systematically investigated. The results indicated that weak dynamic disturbance decreased the stress level and made the rockburst occur more easily. The type of structural plane changed the influence of the weak dynamic disturbance on the structural rockburst. For the specimens with unexposed structural planes, more rock split and collapsed but fewer local rockbursts occurred, the intensity of the final rockburst was smaller than that of the static loading, and the stress when the final rockburst occurred was approximately 9% lower compared with those without a weak dynamic disturbance. For the specimens with exposed structural planes, the stress when the final rockburst occurred was approximately 10% lower but with a higher rockburst intensity compared with those without a weak dynamic disturbance. The AE characteristics indicated that tensile fractures dominated the rock failure process during the weak dynamic disturbance. The proportion of shear fractures increased with the increasing number of weak dynamic disturbances. In addition, the characteristics of the energy release indicated that weak dynamic disturbance decreased the local energy release rate (LERR) of the unexposed structural planes but increased the LERR of the exposed structural planes. The dip angle of the structural plane had an obvious effect on the rockburst. As the dip angle of the unexposed structural planes increased, the rockburst intensity, variation in the AE parameters, and LERR initially increased and then decreased which indicated that the rockburst was more intense under the dip angles of 30° and 45°. For exposed structural planes, the rockburst intensity, variation of the AE parameters, and LERR increased with increasing dip angle (0°–60°), which indicated that the 60° dip angle was more dangerous. Highlights: The physical simulation tests of the rockburst process of surrounding rocks with a small structural plane near the excavated boundary under the weak dynamic disturbance were successfully carried out. The weak dynamic disturbance decreases the stress level when the structural rockburst occurs and promotes the occurrence of rockburst. Under weak dynamic disturbances, the influence of the structural plane dips of surrounding rock on rockburst is significant and cannot be ignored. With the increasing dip angle of the unexposed structural planes, the rockburst intensity, variation of the AE parameters, and LERR first increase and then decrease. With the increasing dip angle of the exposed structural planes, the rockburst intensity, variation of the AE parameters, and LERR increase. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Central South University is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As a unique geological hazard in a high-geo-stress environment, rockburst happens with strong suddenness, randomness, and destructiveness, but the mechanism of its occurrence in a deep-buried tunnel in a high-geo-stress environment needs further study. Based on the analyses of the stress field of the rockburst section of Ping'an Tunnel, which is over-long and deep-buried, the occurrence mechanism of rockburst is figured out. Furtherly, the intensity and location of rockburst are predicted by using the rockburst criterion. Results show that there exists large compressive stress at the side wall of the tunnel, which is the main cause of rockburst. Under a high-geo-stress condition, due to the existence of unfavorable factors like structural planes, high intensity rockburst is likely to happen in the middle of the tunnel face after the sudden release of original rock stress. Arranging stress-releasing holes in the rockburst section can effectively reduce the possibility of rockburst by releasing the original rock stress in advance. The research results can deepen the understanding of the mechanism of rockburst in a high-geo-stress environment and provide scientific basis for the prevention and control of rockburst in similar engineering projects. [ABSTRACT FROM AUTHOR]

The gradual depletion of shallow resources necessitates the imperative shift towards deep mining. In deep mining, dynamic disasters, such as rockburst, caused by high in-situ stress and other complex geological environments, have persistently posed a significant challenge to the safe and efficient extraction of deep minerals. Despite the longstanding occurrence of rockburst disasters, they have not been effectively resolved due to limitations in their occurrence mechanisms and monitoring methods. In this paper, the evaluation system and the prevention and control technology of rockburst were systematically summarized and concluded through literature research. The current research progress shows that there are many evaluation systems of rockburst, which can evaluate and predict the grade and tendency of rockburst disasters well. Regarding rockburst prevention and control systems, they can generally be classified into passive and active control technology based on the timing of disaster management and protective mechanisms. The overall planning concept was developed based on mining plan optimization and stress environment reconstruction, providing a new idea and method for rockburst prevention and control in deep mining of metal mines. Finally, taking the deep mining of Sanshandao Gold mine as the background, the advantages and effects of the unloading mining scheme in rockburst control and prevention under the integrated planning concept were verified, which provided an effective reference for the advanced intervention and active prevention and control of rockburst in deep mining of metal mines in the future. [ABSTRACT FROM AUTHOR]

Rockburst is a phenomenon where sudden, catastrophic failure of the rock mass occurs in underground deep regions or areas with high tectonic stress during the excavation process. Rockburst disasters endanger the safety of people's lives and property, national energy security, and social interests, so it is very important to accurately predict rockburst. Traditional rockburst prediction has not been able to find an effective prediction method, and the study of the rockburst mechanism is facing a dilemma. With the development of artificial intelligence (AI) techniques in recent years, more and more experts and scholars have begun to introduce AI techniques into the study of the rockburst mechanism. In previous research, several scholars have attempted to summarize the application of AI techniques in rockburst prediction. However, these studies either are not specifically focused on reviews of the application of AI techniques in rockburst prediction, or they do not provide a comprehensive overview. Drawing on the advantages of extensive interdisciplinary research and a deep understanding of AI techniques, this paper conducts a comprehensive review of rockburst prediction methods leveraging AI techniques. Firstly, pertinent definitions of rockburst and its associated hazards are introduced. Subsequently, the applications of both traditional prediction methods and those rooted in AI techniques for rockburst prediction are summarized, with emphasis placed on the respective advantages and disadvantages of each approach. Finally, the strengths and weaknesses of prediction methods leveraging AI are summarized, alongside forecasting future research trends to address existing challenges, while simultaneously proposing directions for improvement to advance the field and meet emerging demands effectively. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To investigate the influence of water content on the rockburst phenomena in tunnels with horizontal joints, experiments were conducted on simulated rock specimens exhibiting five distinct levels of water absorption. Real-time monitoring of the entire blasting process was facilitated through a high-speed camera system, while the microscopic structure of the rockburst debris was analyzed using scanning electron microscopy (SEM) and a particle size analyzer. The experimental findings revealed that under varying degrees of water absorption, the specimens experienced three stages: debris ejection; rockburst; and debris spalling. As water content increased gradually, the intensity of rockburst in the specimens was mitigated. This was substantiated by a decline in peak stress intensity, a decrease in elastic modulus, delayed manifestation of pre-peak stress drop, enhanced amplitude, diminished elastic potential energy, and augmented dissipation energy, resulting in an expanded angle of rockburst debris ejection. With increasing water content, the bond strength between micro-particles was attenuated, resulting in the disintegration of the bonding material. Deformation failure was defined by the expansion of minuscule pores, gradual propagation of micro-cracks, augmentation of fluffy fine particles, exacerbation of structural surface damage akin to a honeycomb structure, diminishment of particle diameter, and a notable increase in quantity. Furthermore, the augmentation of secondary cracks and shear cracks, coupled with the enlargement of spalling areas, signified the escalation of deformation failure. Simultaneously, the total mass of rockburst debris gradually diminished, accompanied by a corresponding decrease in the proportion of micro and fine particles within the debris. [ABSTRACT FROM AUTHOR]

Microseismic data are widely employed for assessing rockburst risks; however, significant disparities exist in the monitoring capabilities of seismic networks across different mines, and none can capture a complete dataset of microseismic events. Such differences introduce unfairness when applying the same methodologies to evaluate rockburst risks in various mines. This paper proposes a method for assessing the monitoring capability of seismic networks applicable to heterogeneous media in mines. It achieves this by integrating three gradient boosting algorithms: Extreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), and Categorical Boosting (CatBoost). Initially, the isolation forest algorithm is utilized for preliminary data cleansing, and feature engineering is constructed based on the relative locations of event occurrences to monitoring stations and the working face. Subsequently, the optimal hyperparameters for three models are searched for using 8508 microseismic events from the a Coal Mine in eastern China as samples, and 18 sub-models are trained. Model weights are then determined based on the performance metrics of different algorithms, and an ensemble model is created to predict the monitoring capability of the network. The model demonstrated excellent performance on the training and test sets, achieving log loss, accuracy, and recall scores of 7.13, 0.81, and 0.76 and 6.99, 0.80, and 0.77, respectively. Finally, the method proposed in this study was compared with traditional approaches. The results indicated that, under the same conditions, the proposed method calculated the monitoring capability of the key areas to be 11% lower than that of the traditional methods. The reasons for the differences between these methods were identified and partially explained. [ABSTRACT FROM AUTHOR]

Aiming at roadway rockbursts induced by near-field dynamic disturbances, this study explored the mechanical response and failure mechanism of anchored roadway surrounding rocks under this condition through the similarity simulation experiment and theoretical modeling analysis. Results show that the greater the disturbance energy is, the stronger mechanical response of surrounding rocks while the faster its attenuation. The starting acceleration amplitude is relatively smaller while the braking acceleration amplitude is larger in the bolt densification area, which has a better self-stabilizing ability. Anchored roadway surrounding rocks exhibit local impact failure characteristics, and the region facing disturbance is most seriously damaged. The bolt-mesh-cable support structure shows the good resistance to low-energy disturbances, while the impact failure is induced with damages inside support structure increasing abruptly under high-energy disturbances. The impact resistance of local surrounding rocks can be improved by bolt densification. Based on the failure criterion, the surrounding rocks only undergo impact failure in the region facing disturbance, while quasi-static failure occurs in remaining regions. The experimental and theoretical research results have been verified through in-situ measurements, which can provide an important reference for the mechanism and prevention of roadway rockburst under near-field dynamic disturbance. [ABSTRACT FROM AUTHOR]

The precise forecasting of rockburst is fundamental for safeguarding human lives and property, upholding national energy security, and protecting social welfare. Traditional methods for predicting rockburst suffer from poor accuracy and extended model training durations. This paper proposes a distributed training rockburst prediction method called Distriformer, which uses deep learning technology combined with distributed training methods to predict rockburst. To assess the efficacy of the Distriformer rockburst model proposed herein, five datasets were used to compare the proposed method with Transformer and Informer. The experimental results indicate that, compared with Transformer, the proposed method reduces the mean absolute error by 44.4% and the root mean square error by 30.7% on average. In terms of training time, the proposed method achieves an average accelaration ratio of 1.72. The Distriformer rockburst model enhances the accuracy of rockburst prediction, reduces training time, and serves as a reference for development of subsequent real-time prediction models for extensive rockburst data. [ABSTRACT FROM AUTHOR]

Upon reaching deeper levels of extraction, dynamic hazards such as rockburst become more pronounced, with the high energy storage characteristics of rock masses in high-stress environments being the fundamental factor behind rockburst disasters. Additionally, deep-seated mineral extraction commonly involves drilling and blasting methods, where the vibrational energy generated by mining explosions combines with the elastic energy of rock masses, leading to a sudden growth in the risk and intensity of rockburst disasters. This paper, with deep mining at Sanshandao Gold Mine as the focal point, systematically investigates the impact of blasting vibrations on rockburst disasters in deep mines. Initially, based on extensive data on measured geostress considering the tri-arch cross-section form of deep tunnels, the elastic energy storage of the surrounding rocks in deep tunnels was calculated. The results indicate that the maximum energy storage of the surrounding rocks occurs at the bottom of the tunnel, with the peak accumulation position located at a distance of five times the tunnel radius. On this basis, the Map3D numerical simulation analysis was adopted to systematically capture the accumulation behavior and distribution characteristics of disturbance energy. Subsequently, by conducting the dynamic impact experiments with an improved Split Hopkinson pressure bar (SHPB) and monitoring vibration signals at various locations, the paper provides insights into the propagation patterns of impact energy in a long sample (400 mm in length and 50 mm in diameter). Analysis of the scattering behavior of vibrational energy reveals that the combined portion of blasting vibration energy constitutes 60% of the total vibrational energy. Finally, a rockburst disaster evaluation model based on energy accumulations was proposed to analyze the rockburst tendencies around deep tunnels. The results indicated that the disaster-driven energy increased by 19.9% and 12.2% at different places on the roadway. Also, the probability and intensity of a rockburst would be raised. [ABSTRACT FROM AUTHOR]

Microwave irradiation has been considered a promising solution for high-temperature cracking rock. Most of the current researches are concentrated on investigating the effects of microwave irradiation on the physical and mechanical properties of rock. However, there is a paucity of reports on the application of microwave irradiation for controlling rockburst disasters. The novelty of this investigation lies in the utilization of microwave irradiation to modify the energy storage capacity and fracture characteristics of brittle rock with rockburst proneness. Based on the phenomenon of overheating in rock under microwave irradiation, the concept of progressive damage in granite was proposed for the first time. The weakening of energy storage capacity due to microwave irradiation was evaluated by defining an energy storage coefficient. A novel index for assessing the rockburst proneness of brittle rock was proposed. By combining this index with the strain energy release rate, the potential value of microwave irradiation in reducing the proneness and intensity of rockburst was explored. This study also introduced the concept of ''sensitive stress level'' which influences the closure state of cracks, and found that SSL and mechanical properties show high sensitivity to microwave power. A threshold power of 4.5 kW was identified, at which numerous parameters undergo significant changes.

In order to explore a new method and mode of gently inclined hard roof treatment, the hydraulic fracturing axial roof cutting technology based on abrasive jet is introduced, and the key technical parameters of abrasive jet axial cutting and fracturing are determined based on indoor experiments and field industrial experiments. Taking the mining of working face under the condition of hard roof in Kuangou Coal Mine as the background, the implementation process and the effect of mining process are tested by means of water pressure gauge, drilling peep and observation well water level observation, mi-croseismic monitoring, support fracture monitoring and coal stress monitoring. The research results show that the key technical parameters of slotting and fracturing are mastered in the axial cutting test of abrasive jet. Wherein the kerf depth is 200 m, the kerf length is 300 m, the kerf pressure is 40–50 mpa, the fracturing pressure is 50–55 mpa, and the fracturing time is 20–30 min. After grooving fracturing, the cracks in the roof strata are effectively generated and expanded, which destroys the integrity of the roof, and the fracturing radius is 10–20 m. During the mining period, compared with the tradi-tional blasting technology, the concentrated area of microseismic events was shifted from 80 m in front of the working face to 130 m after the combined treatment of abrasive jet axial roof cutting and blasting, and the microseismic energy release was mainly small energy events. After the application of abrasive jet axial roof cutting and scour prevention technology in hard roof, the periodic weighting step is obviously reduced, the influence range of mining stress and stress concentration coefficient are obviously reduced, the activity intensity and dynamic load effect of surrounding rock are obviously weakened. The research results provide a basis for effective prevention and control of rockburst disasters under the condition of hard roof.