Rock bursts are devastating hazards induced by the coupling of geological dynamic environments and mining-induced disturbances, which trigger a sudden release of energy when accumulated elastic strain exceeds the strength threshold of rock masses.As one of the key characterization parameters of the geological dynamic environment, the crustal deformation characteristics of the mining area can effectively reveal the dynamic evolution law of the overlying coal and rock mass structure from stress deformation to instability failure during the mining process of the underground working face.Based on the GNSS monitoring data of Junde mining area, through the analysis of the crustal deformation characteristics of Junde coal mine, it is determined that the crustal deformation of Junde coal mine area shows a trend of extrusion to the southeast as a whole, and its horizontal movement direction is consistent with the overall movement direction of the region as a whole, showing SEE direction, with an average movement rate of about 30 mm / a ; By comparing the vertical time series of 3 # station with the time series of energy events, most of the time periods show the phenomenon of rising and falling at the same time. It is determined that when the energy background value is high (exceeding 100 events/day), if the GNSS station exhibits a rapid vertical subsidence reaching 30 mm, the Junde Coal Mine faces a significantly increased probability of large-energy events. Through the analysis of the influence of the epicentral distance of the earthquake on the vertical movement of the crust and the characteristics of energy events, it is determined that the vertical rapid decline of GNSS stations is related to the epicentral distance. The farther the epicentral distance, the greater the rapid decline of GNSS stations before the occurrence of large energy events of the same magnitude.

The change of stope migration caused by the failure and instability of the overlying thick key strata has a control effect on the occurrence of rock burst in front of the working face. The main disaster-causing factors of rock burst in front of the working face are explored to predict and prevent rock burst. Through the distribution characteristics of microseismic energy events, it is determined that the instability of hard roof has a great influence on the mining of working face. The influence mechanism of the instability and fracture of the overlying hard rock strata on the rock burst of the working face is clarified, and the distribution of the advance abutment pressure of the working face and the energy accumulation of the coal and rock mass under the static load condition are calculated by establishing the mechanical model of the advance abutment pressure of the working face under the condition of full mining. The superposition of dynamic and static load energy on the working face by the initial and periodic instability fracture and synergistic fracture energy release of the overlying hard rock strata is calculated theoretically. It is determined that the superposition energy transmitted to the working face by the synergistic fracture of the middle and low hard rock strata is 1.23 × 104 J, which is higher than the critical energy of Gengcun rock burst. The low hard rock layer is determined as the monitoring target layer, and the on-line monitoring scheme of hard rock layer activity is established. The dynamic change of anchor cable data of stress evolution law of low hard rock layer in the process of working face mining is quantitatively determined, which reflects the stress evolution law of coal and rock mass in front of working face, and quantitatively determines the three-stage division of the influence of working face mining on coal and rock mass in front of working face.

Coal mining industry has complex geological conditions, high safety risks, frequent mine dynamic disasters such as rock burst, coal and gas outburst, which are the core problems restricting the safe production of coal mines and affecting the high-quality development of the industry. The traditional disaster prevention and control technology is mainly concentrated in the combination of local areas of the mine field and a single influencing factor, which is difficult to adapt to the complex geological environment of multi plate intersection and active tectonic activity in China. There are problems such as insufficient prediction accuracy, weak prevention and control pertinence, and imperfect technical system. In view of the above difficulties, this paper systematically combs the whole process of the introduction, adaptation, iterative optimization and independent innovation of the geo dynamic zoning theory in China for more than 30 years, focuses on the application scenarios in the field of mine safety, summarizes and sorts out the technical iteration process, core innovation achievements, engineering application achievements and existing technical shortcomings of the theoretical system, and systematically improves the geo dynamic zoning research system and engineering application paradigm adapted to China’s geological characteristics. Using the research methods of theoretical innovation, technology research and development, system integration and engineering verification, relying on the theory of plate tectonics and the principle of geodynamics, breaking through the limitations of the application of Russia's primary geodynamic zoning theory, and combining the regional geological characteristics of the intersection of three tectonic domains, the development of fault structures, and the active neotectonic movement in China, we carried out multi-dimensional and multi-level technological innovation and practice optimization. At the basic theoretical level, the "three conditions" criterion for the occurrence of mine dynamic disasters is established, the coupling mechanism of the three core elements of geological dynamic environment, mining disturbance and prevention and control measures is clarified, the national first-class geological dynamic zoning work is completed, the national geological dynamic cell bureau is divided, the macro spatial distribution characteristics of "1-1-0" of mine dynamic disasters in China are revealed, and the differential distribution characteristics of disasters in the Tan Lu fault zone, the Qinling Dabie orogenic belt and the Sichuan basin tectonic area are clarified, which provides a theoretical basis for the prevention and control of mine disasters at the national scale. At the technical method level, three core methods, namely multi factor pattern recognition risk prediction, quantitative evaluation of geo dynamic environment and evolution analysis of coal and rock dynamic system, have been formed to break through the limitations of traditional single geological factor analysis and realize the transformation of mine dynamic disasters from qualitative research and judgment to quantitative prediction and from local analysis to overall analysis. At the system R&D level, three software systems are developed iteratively, including rock mass stress state analysis, multi factor pattern recognition risk prediction, and geo dynamic zoning information management. An integrated data integration and visual management platform is built to achieve efficient integration and intelligent analysis of geological data, structural parameters, stress data, and disaster information. In terms of monitoring technology, integrate the global navigation satellite system (GNSS), interferometric synthetic aperture radar (InSAR) surface deformation monitoring, mobile seismic network seismic monitoring, and underground fault activity dynamic monitoring technology, build an integrated surface-underground multidimensional monitoring system, and effectively improve the ability of mine dynamic disaster precursor information capture and risk prediction. Relying on theoretical and technological innovation, the research team has formed a patented technology and industry standard system covering disaster prediction, monitoring, prevention and control. Relevant technical concepts have been incorporated into the 2016 version of the coal mine safety regulations and the 2018 version of the detailed rules for the prevention and control of coal mine rockburst, realizing the deep integration of scientific research achievements and industry standards. By comparing the research systems at home and abroad, it is found that there are some problems in foreign related research, such as difficulty in adapting to deep complex engineer scenes and limited engineering practicability. China’s research has formed significant technical advantages in multi factor coupling analysis, quantitative prediction, engineering adaptability, and systematic application. At the same time, identify the shortcomings of the current research, including the lack of disaster prediction accuracy under complex geological conditions, the low level of technical intelligence, and the lack of dynamic adaptive prevention and control ability. Based on the existing research foundation, in the future, we will focus on technical breakthroughs such as optimization of generalized pattern recognition algorithm, intelligent automatic division of fault block structure, accurate simulation of three-dimensional rock mass stress, and dynamic application evaluation of geo dynamic environment, integrate cutting-edge technologies such as big data, artificial intelligence, and machine learning, build an intelligent, refined, and integrated geo dynamic zoning technology system, promote the in-depth integration of geo dynamic zoning and mine dynamic disaster prevention and control technology, comprehensively improve the level of intelligent prevention and control of coal mine dynamic disasters in China, and provide solid theoretical support and technical support for mine safety production and high-quality development of the industry.

This study investigates the mechanical properties and damage mechanisms of bolt-resin-rock anchorage systems subjected to shear under dynamic normal disturbances. The effects of initial normal load F-nd, cyclic normal amplitude f(a), cyclic normal frequency f, and shear rate v on the shear load, normal displacement, wear characteristics and strain evolution are analysed. The test results show that the peak shear load decreases by 7.82 % similar to 28.95 % with increasing f(a), whereas it increases linearly by 15.77 % similar to 79.85 % with F-nd. The load bearing capacity of the anchorage system is significantly weakened with increasing f, but is not sensitive to the changes of v. The system undergoes shear-induced consolidation and exhibits normal shear contraction during the initial shearing stage. As shearing progresses, the developing penetration plane enhances the climbing effect, leading to pronounced normal dilation. The resin-rock interface is more prone to debonding failure under intensified normal disturbances, whereas the shear penetration surface forms at the bolt-resin interface under high-frequency but low-amplitude normal disturbances. The force chain evolution characteristics of the anchorage system under dynamic normal disturbances from a mesoscopic perspective are analysed via the particle flow numerical simulation method from 3D point, including interface shear force distribution, cracks propagation patterns, and debonding failure mechanisms.

Taking the mining of extra-thick coal seam of Carboniferous hard overburden in tongxin coal mine of datong mining area as the engineering background, the movement characteristics of hard overburden in fully-mechanized caving mining of 3–5 # extra-thick coal seam are analyzed based on the key stratum theory. Based on the elastic plate theory, the mechanical model and mathematical model of the cylindrical shell structure of hard overburden in large space stope are established, and the ultimate span of the cylindrical shell structure is determined and applied in 8105 working face.The results show that the limit span of sub-key stratum II in 8105 working face is 65.11 m, and the limit span of main key stratum is 222.77 m. The calculation results are basically consistent with the actual mine pressure behavior. The mechanism of special mine pressure phenomena such as large and small periodic weighting, large mining influence range and easy impact load in the mining process of 8105 working face is revealed, which provides a theoretical basis for mine pressure control in the mining face of Carboniferous hard overburden and extra-thick coal seam in Datong mining area.

In order to identify the spatial distribution and properties of fracture network, as well as pre-production water saturation distribution and stress sensitivity of multi-stage fractured horizontal well for unconventional oil and gas reservoir, a data assimilation algorithm is proposed in this work. In terms of model establishment and parameterization, the fracture network is conceptualized as comprising a major fracture and a Stimulated Reservoir Volume (SRV), which is created through the interconnection of secondary and natural fractures. The major fracture is characterized by permeability, porosity, and half-length. The SRV is represented using the double-porosity double-permeability (DPDP) model, and is characterized by its spatial distribution and the DPDP model parameters. While, the SRV spatial distribution is characterized by the level set function. Pre-production water saturation is assumed to be a function of the vertical distance from horizontal well. Reservoir stress sensitivity is taken into consideration by considering the change of transmissibility with reservoir pressure. The data assimilation algorithm employs the ensemble-based iterative data assimilation algorithm. The implementation process of the algorithm is based on covariance information, which avoids the calculation of gradient and is easy to implement. The data assimilation case studies involving a shale gas well in Fuling and two tight oil wells in Jimsar Sag of the eastern Junggar Basin in China demonstrate that compared with the initial ensemble, the updated ensemble by data assimilation can better fit the data and have reliable prediction in the pure prediction stage. The SRV exhibits different spatial extents at different fracturing stages. The pre-production water saturation varies with the changes in the vertical distance from horizontal well. The reservoir may be stress-sensitive, and its identification requires observation data that are responsive to such sensitivity.

Rock burst is the result of the coupling effect of geological dynamic environment and mining engineering disturbance.The crustal deformation characteristics of mining area are one of the important influencing factors of geological dynamic environment,which can directly reflect the dynamic evolution characteristics of stress deformation-instability of overlying coal and rock mass structure in un-derground working face mining.The disturbance of mining engineering increases the stress of coal and rock mass and accumulates energy.When the critical condition of coal and rock is reached,it is easy to induce the instantaneous release of energy and cause the disaster of rock burst.Therefore,there is a close relationship between the regional crustal deformation characteristics and rock burst in the mining area.In order to deeply analyze the relationship between the crustal deformation characteristics and the micro-seismic energy events of rock burst in the mining area,based on the InSAR monitoring data of Hegang mining area,the temporal and spatial evolution characterist-ics of surface deformation in Fuli coal mine,Xing'an coal mine and Junde coal mine were studied.Taking the second section of the work-ing face of the 17-layer three-four area of Junde coal mine as an example,the InSAR monitoring results of 10 points in the region were se-lected,and the average crustal deformation characteristics and the total energy of rock burst micro-seismic were comprehensively ana-lyzed,and the"time-space-strong"characteristics of the occurrence of high-energy micro-seismic events and regional crustal deformation were quantitatively determined.The research shows that the vertical deformation of the crust in the mine field of Junde Coal Mine is con-sistent with the total energy change trend of the 17-layer microseismic events,reaching 69%,and there is a high consistency in time fre-quency.The energy of 24 large-energy microseismic events in the typical period(2020-12-02-2021-12-28)and the average deforma-tion of 10 monitoring points were selected for Pearson correlation analysis.It was concluded that the magnitude of microseismic energy was positively correlated with the average deformation,and the correlation coefficient was 0.56.The epicentral distance was negatively correlated with the average deformation,and the correlation coefficient was-0.75,which reflected the spatial and intensity relationship between crustal deformation characteristics and rock burst.It shows that InSAR monitoring has a high degree of matching with microseis-mic events in time,space,deformation and microseismic monitoring.

The activation of reverse faults can significantly increase the risk of rock burst, as the fault's dip angle and stiffness control the accumulation and release of energy that triggers such events. To assess the impact of varying fault dip angles and stiffness on rock burst risk in coal mines, this study uses the F16 reverse fault in Gengcun Coal Mine, located in the Yima mining area, as a case study. Through a combination of theoretical analysis, numerical simulations, and field monitoring, the study investigates how changes in fault dip angle and stiffness influence the evolution of the stress field in the working face and the activation-induced instability of the fault. The results show that when the dip angle of the reverse fault exceeds 60°, significant concentrations of shear and vertical stresses occur, increasing the slip risk coefficient (β) and making the fault more susceptible to activation. Additionally, when the fault stiffness ratio is below 1/5, the peak abutment stress ahead of the working face rises, and horizontal displacement grows nonlinearly, creating a “stress barrier” effect. This intensifies energy accumulation in the coal seam and elevates the risk of rock burst. Using the F16 reverse fault as an example, it is shown that the 13200 working face at Gengcun Coal Mine lies within the fault's influenced zone. Monitoring data from the F16 fault reveal that mining activities at the 13200 working face triggered the activation of the fault, leading to the concentrated release of accumulated energy in the coal-rock mass and the occurrence of five high-energy microseismic events. This study offers valuable theoretical insights and practical guidelines for predicting and preventing fault-induced rock burst.

Rock burst results from the interaction of multiple factors.Its occurrence is not only related to mining engineering effects but also closely linked to the geo-dynamic environment of the mine.In complex geodynamic conditions,rock burst occurs more frequently.To study the influencing factors of rock burst in such environments,methods such as theoretical analysis,field monitoring,and geological ex-ploration are employed,with 12240 working face of Gengcun Coal Mine as the research subject.The study analyzes the geodynamic envir-onment characteristics of Gengcun Coal Mine and assesses the risk of rock burst.The critical depth for rock burst at 12240 working face is calculated,and this depth is verified using rock burst and large energy microseismic events,revealing the relationship between the occur-rence depth of rock burst and its source.The"three-condition criterion for rock burst"is used to analyze the frequency,energy,and spatial distribution of microseismic events.By analyzing changes in the frequency and energy of microseismic events before and after roof pre-splitting blasting at 12240 working face,and examining the results from borehole inspections after pre-splitting blasting,the effectiveness of the far-field hazard mitigation measures for 12240 working face is verified.The research results indicate that Gengcun Coal Mine has a medium level of geo-dynamic disaster environment and is a serious rock burst mine.The critical depth for rock burst occurrence at Gengcun Coal Mine is an elevation of-545.79 meters.The burial depth of 12240 working face is close to this critical depth,indicating a risk of rock burst.The F16 fault,as a major geological structural factor at Gengcun Coal Mine,is an important component of the geo-dy-namic environment and provides an energy basis for the formation and occurrence of high-energy rock burst.Mining effects are a suffi-cient condition for rock burst but have little impact on 12240 working face during the initial mining period.Hazard mitigation measures are control conditions that effectively reduce the risk of rock burst at 12240 working face.The research results provide a basis and reference for preventing and controlling dynamic disasters such as rock burst in complex geodynamic environments.

In order to establish a quantitative relationship between fault activity and rock burst,realize the effective prevention and control of rockburst.We analyzed the geological structure environment of rockburst in Yima mining area theoretically,and analyzed the relative position relationship between panel 13200 and fault influence zone in Gengcun coal mine by taking the evaluation method of geo-dynamic conditions of rockburst.We further discussed the macro-control effect of the fault structure on rock burst.On this basis,we calculated the tectonic stress in the minefield and divided the tectonic stress into different zones,and analyzed the control effect of tectonic stress on rockburst.We designed the actual quantitative monitoring method of underground fault,monitored the activity of F16 fault in Gengcun mine field directly,analyzed the changes of fault displacement and stress increase during the preparation and occurrence of high-energy microseismic events quantitatively.We constructed a model of"the scale of coal and rock mass in the focal area is equal to that of the dy-namic core area,and the energy of the focal area gradually attenuates with the transmission distance,"which provides an important tool for establishing the relationship between large-energy microseismic events and fault activities,establishes the relationship between high-en-ergy microseismic events and fault activities,and determines the influence of fault activity on rock burst.The research results show that in Yima coalfield,the complex thrust nappe structure system constitutes the geological tectonic background of rockburst in Yima mining area.The width of F16 fault influence zone is 7 000 to 7 600 m,and the whole panel 13200 is within the influence zone of F16 fault,which further increases the risk of rockburst under the influence of mining activities.The areas controlled byⅠ-2 fault,Ⅲ-4 fault andⅣ-7 fault are the main areas for the occurrence of rockburst and large energy microseismic events in Gengcun Coal Mine.Most of the rockburst and large energy microseismic events are located in stress gradient areas.During the preparation and occurrence of large energy microseismic events,the displacement of F16 fault increased by 50 mm and 45 mm respectively.Before the two large energy microseismic events occur,the increase of fault activity tension are relatively the highest,which are 2.58 kN and 2.93 kN.The rapid increase of fault displacement and higher stress increase constitute the main energy source of large energy microseismic events.The occurrence of large energy microseismic events and rockburst are closely related to the activity of faults.The actual quantitative monitoring method of underground faults can be widely used in the guidance of mine rockburst prediction and prevention and control.

Coal and rock dynamic disasters occur frequently in deep coal mining. The loading rate affects the mechanical properties and behaviors. Uniaxial compression acoustic emission (AE) tests of bump-prone coal under various loading rates were carried out, and the mechanical properties, AE spatiotemporal evolution, and spatial fractal characteristics were analyzed. The experimental results indicate that the uniaxial compressive strength is positively related to the loading rate, and the elastic modulus increases before decreasing with the loading rate. The failure strain is positively related to the loading rate, and the percentage of the compaction phase relative to the pre-peak phase decreases with the loading rate. The hit rate, absolute energy, AE events, and amplitude evolution of coal samples under various loading rates are the same, and the maximum of AE absolute energy and hit rate is positively related to the loading rate. The spatial evolution of AE events of coal samples under various loading rates is the same, showing a “slow increase → slow increase → fast increase → rapid increase → slow increase” trend. The spatial fractal dimension ranges from 2.1 to 2.9, and the evolution of coal samples under various loading rates is the same, exhibiting a downward trend.

The crustal deformation characteristics of the mining area are a reflection of the evolution of the overburden rock structure force and deformation of coal seam mining, Impact geopressure is a result of the overburden rock movement, which disrupts the stress balance of the coal rock body surrounding the quarry, leading to a dynamic disaster, and the crustal deformation characteristics are closely related to Impact geopressure.To gain a deeper understanding of the relationship between crustal deformation and impact ground pressure in the Hegang mining region. Using the available GNSS observation data from the study area, six new GNSS observation stations in the key areas of the mining region have been encrypted, a thorough analysis is conducted on both the regional microseismic events catalog and the mine earthquake events catalog, which are under the surveillance of seismic stations, and the regional crustal deformation overtime during the occurrence of larger energy events is studied quantitatively. The findings indicate a direct relationship between the frequency of energy occurrences in the mining region and the vertically aligned time series of the GNSS stations, as the vertical direction experiences a rapid decline, the magnitude increases and the greater the cumulative energy emitted by the subsequent energy occurrences. The findings of this research can serve as a point of reference for proactively alerting and averting microseismic energy incidents in the southern mining region of Hegang

In order to obtain the characteristics of the effects of cyclic impact loading on the damage of coal-rock in the presence of a local static load constraint, the evolution of the damage factor and the fracture rate during the process and incremental cyclic impact on raw coal and briquettes has been studied. Experimental results show that the presence of local static load restraint improves the impact resistance of the coal-rock, and the damage factor of the coal-rock shows obvious zoning characteristics. When the coal-rock is in an elastic state, the partition with a larger static load restraint area has stronger impact resistance, when the coal-rock is in a plastic state, the partition with a larger static load restraint area has a weaker impact resistance. Increasing impulsive cyclic impacts have a higher damage efficiency to coal-rock than constant impulsive cyclic impacts. The difference in rock breaking efficiency between the two cyclic impact methods is mainly reflected in the partition with the largest constrained area. The crack propagation on the coal-rock surface is more consistent with the partition characteristics of the damage factor. When the static load constrained zone is in an elastic state, the static load has an inhibitory effect on the crack growth. When the static load confinement zone is in a plastic state, the cracks mainly propagate in the static load confinement zone, and the constrained zone mainly consists of tensile cracks that grow in the vertical direction, while the cracks in the non-constrained zone mainly grow in an oblique direction. Finally, fracture mechanics was applied to analyze the failure type of the sample.

Rockbursts are some of the most severe dynamic disasters in coal mines. In this paper, the discrimination method of the tectonic stress field is proposed by analyzing the modern stress field in China. The tectonic stress field formed by modern tectonic movement guides in situ stress measurements. According to the stress state classification, most rockbursts in coal mines in China are closely associated with tectonic stress. For tectonic stress-driven rockbursts, modern tectonic movement and modern tectonic stress fields must be considered. The stress change and energy transfer caused by tectonic movement affect the geological structure where coal mines are located. Energy accumulation under rockburst conditions is mainly formed by natural geo-dynamic movement and the mining configuration, and energy accumulation is the basis for rockbursts. The application of the geo-dynamic environmental evaluation method to determine the coalfield geo-dynamic process and the influence of modern tectonic movement is proposed. Accordingly, the classification method of rockbursts in coal mines is established. Based on the distribution characteristics of modern tectonic conditions in China, it is revealed that these dynamic disasters follow a “110” distribution. Finally, a “three condition” criteria of rockbursts is proposed: the geo-dynamic environment is a necessary condition for rockbursts, mining disturbance is a sufficient condition for rockbursts, and risk-releasing measures are a condition controlling rockburst risk mitigation.

Rock burst induced by mining is one of the most serious dynamic disasters in the process of coal mining. The mechanism of a rock burst is similar to that of a natural earthquake. It is difficult to accurately predict the “time, space, and strength” of rock burst, but the possibility of rock burst can be predicted based on the results of microseismic monitoring. In this paper, the rock burst system under the tectonic stress field is established based on the practice of coal mining and the result of mine ground crustal stress measurement. According to the magnitude of microseismic monitoring, the amount of the energy and spatial position of the rock burst are determined. Based on the theory of explosion mechanics, aiming at the prevention and control of rock burst in the coal mine, the technique of liquid CO2 fracturing blasting is put forward. By the experiment of blasting mechanics, the blasting parameters are determined, and the controlling mechanism of rock burst of liquid CO2 fracturing blasting is revealed. The application of liquid CO2 fissure blasting technology in the prevention and control of rock burst in Jixian Coal Mine shows that CO2 fracturing blasting reduces the stress concentration of the rock burst system and transfers energy to the deeper part, and there is no open fire in the blasting. It is a new, safe, and efficient method to prevent and control rock burst, which can be applied widely.

In order to predict the residual gas content in coal seam in front of roadway advancing face accurately and rapidly, an improved prediction method based on both drilling cuttings indices and bat algorithm optimizing extreme learning machine (BA-ELM) was proposed. The test indices of outburst prevention measures (drilling cuttings indices, residual gas content in coal seam) during roadway advancing in Yuecheng coal mine were first analyzed. Then, the correlation between drilling cuttings indices and residual gas content was established, as well as the neural network prediction model based on BA-ELM. Finally, the prediction result of the proposed method was compared with that of back-propagation (BP), support vector machine (SVM), and extreme learning machine (ELM) to verify the accuracy. The results show that the average absolute error, the average absolute percentage error, and the determination coefficient of the proposed prediction method of residual gas content in coal seam are 0.069, 0.012, and 0.981, respectively. This method has higher accuracy than other methods and can effectively reveal the nonlinear relationship between drilling cuttings indices and residual gas content. It has prospective application in the prediction of residual gas content in coal seam.

In order to calculate the critical depth of a typical rockburst coal mine quantitatively, which is helpful in rockburst prevention and control, in this paper, the concept of typical rockburst coal mine and atypical rockburst coal mine is put forward, energy characteristics of a coal-rock dynamic system is identified, and the relationship between rockburst and the coal-rock dynamic system is analysed by the model of the coal-rock dynamic system. Energy characteristics of the coal-rock dynamic system in the gravity stress field, tectonic stress field, and mining stress field are determined, respectively, and corresponding calculation methods are put forward at the same time, and the calculation method of the coal-rock dynamic system energy can forecast the occurrence of rockburst, with an accuracy of 80%. The calculation method of the critical depth in a typical rockburst coal mine is put forward, and the accuracy of which is validated in one typical rockburst coal mine. The degree of coincidence for the result of this method is 93.1%, which shows that the calculation method of a critical depth in a typical rockburst mine is highly reliable and practical, which could be widely used in forecasting the hazard of rockburst in typical rockburst mines. This method will be validated in more coal mines, and the calculation method of the critical depth in an atypical rockburst mine will be further researched in the future.

Understanding the dynamic mechanical behaviors and microstructural properties of outburst-prone coal is significant for preventing coal and gas outbursts during underground mining. In this paper, the split Hopkinson pressure bar (SHPB) tests were completed to study the strength and micro-structures of outburst-prone coal subjected to compressive impact loading. Two suites of coals-outburst-prone and outburst-resistant-were selected as the experimental specimens. The characteristics of dynamic strength, failure processes, fragment distribution, and microstructure evolution were analyzed based on the obtained stress-strain curves, failed fragments, and scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) images. Results showed that the dynamic compressive strength inclined linearly with the applied strain rate approximately. The obtained dynamic stress-strain responses could be represented by a typical curve with stages of compression, linear elasticity, microcrack evolution, unstable crack propagation, and rapid rapture. When the loading rate was relatively low, fragments fell in tension. With an increase in loading rates, the fragments fell predominantly in shear. The equivalent particle size of coal fragments decreased with the applied strain rate. The Uniaxial compressive strength (UCS) of outburst-prone coal was smaller than that of resistant coal, resulting in its smaller equivalent particle size of coal fragments. Moreover, the impact loading accelerated the propagation of fractures within the specimen, which enhanced the connectivity within the porous coal. The outburst-prone coal with behaviors of low strength and sudden increase of permeability could easily initiate gas outbursts.

In order to calculate the concrete scale range of coal and rock mass in rockburst of different degrees of danger and to prevent and control rockburst in coal mines, the concept of dynamic system of coal and rock is put forward in this paper. The model of the relationship between the occurrence of rockburst and dynamic system is built at the same time, which could be used to analyze the rockburst risk of coal and rock in different scales. The calculation method of dynamic nuclear zone scale and its evaluation system and quantitative indicators are put forward based on the energy release process of dynamic system of coal and rock. Combined with the fracturing technology of liquid CO2, the accuracy of the calculation method for the radius of dynamic nuclear zone is verified in a coal mine in Shanxi Province. The degree of coincidence between the results of the two methods is 96.9%∼97.5%, which shows that the calculation method for the radius of dynamic nuclear zone has high reliability and practicability. This method can be widely used in forecasting the risk of rockburst. The liquid CO2 fracturing method can be well used to simulate the blasting source of rockburst at the same time and can be applied to more mines in the future.

In order to reveal the occurrence mechanism of coal and gas outburst and optimize the measures to prevent the disaster, a coal mine in Henan Province was undertaken as the research background. Based on the geological and mining conditions of the coal mine, the gas geological analysis method is applied to determine the outburst occurrence and to classify the risk levels. A multifactor pattern recognition method is used to determine the risk probability of the dynamic disasters such as coal and gas outburst. The relationship between geological structure, rock mass stress, and mine dynamic hazards is determined using geo-dynamic division method and FLAC 3D numerical simulation. The occurrence and manifestation characteristics of the dynamic hazards are determined. COMSOL Multiphysics software is used to evaluate the original prevention measures and to optimize the measures. The research results determine the main influencing factors and regional distribution law of coal and gas outburst, which is of great significance to the risk prediction and prevention of dynamic disasters such as coal and gas outburst.