Outburst Intensity Research Articles

Experimental investigation on the gas pressure influence laws and mechanical mechanism of coal and gas outbursts

With the increasing frequency and intensity of coal and gas outburst disasters under deep mining conditions, studying the outburst mechanism of occurrence has great significance for outbursts prevention and control. The evolution law of coal and gas outbursts under different gas pressure is proposed. The outbursts law is analyzed utilizing the self-developed simulation experiment system of coal and gas outbursts, and the simulation experiment is carried out under the gas pressure of 0.45, 0.8, and 1.5 MPa. In the experiment, the gas pressure drops curves, the relative intensity change, the interval distribution of coal powder, and the evolution of outburst hole and the migration rate of coal powder are analyzed. The results indicate that (1) the gas pressure detected by the No. 4 gas pressure sensor starts to drop first; (2) the gas pressure is positively proportional to the relative outburst intensity. When the gas pressure increases from 0.45 to 0.80 MPa and then to 1.5 MPa, the farthest outburst distance of coal powder increases from 10 to 15 m and then to 21 m, and the corresponding relative outburst intensity increases from 22.94% to 35.74% and then to 45.73%, respectively. (3) The average proportion of coal particles size less than 0.28 mm and larger than 1 mm under each corresponding outburst interval is 40.75% and 22.53%, respectively. Experimental results show that the gas pressure plays an essential role in the secondary crushing and pulverization of coal samples during the outburst process. (4) The throwing velocity of the pulverized coal is increased with the gas pressure near the outburst hole. When the gas pressure is 0.8 MPa, the throwing velocity of pulverized coal reaches the maximum value of 32.40 m/s. (5) The dimensional characteristics and the location initiation of the outburst hole are obtained. The results showed that the outburst process of coal is mainly in two failure forms: pulverization and spallation. The research results provide a theoretical basis and test data support for the prevention and control of coal and gas outburst disasters.

Gas pressure, in-situ stress and coal strength effects on the evolution process of coal and gas outbursts based on the experimental data

ABSTRACT This paper investigated the effects of gas pressure, in-situ stress, and coal strength on coal and gas outbursts (CGO) based on the laboratory CGO experimental data. Based on the hypothesis of the comprehensive of CGO, the single-factor control variable method was used to analyze and evaluate the relative outburst intensity, the characteristics of outburst holes, the distribution of pulverized coal, the drops of outburst gas pressure, and the pulverized coal density under different outbursts experimental condition. The improved CGO energy equation and instability criterion are proposed as a direction to study the occurrence of CGO as an energy evolution direction. Furthermore, the results shows that the initial outburst gas pressure was 0.45 MPa during the experimental conditions of in-situ stress was 5 MPa, and the coal strength was 0.24 MPa. The gas pressure is directly proportional to the relative outburst intensity, while the in-situ stress and coal strength are inversely proportional to the relative outburst intensity. After the CGO occurred, the outburst coal always show spallation and pulverization characteristics. The results highlight that the gas pressure plays a key role in pulverizing and throwing out the pulverized coal, and the in-situ stress mainly plays a role in destroying the coal, and the coal strength plays a resistance role during the CGO occurs. It is also found that pulverized coal particles size less than 0.28 mm can be used to represent the distribution pattern of the total weight of outburst pulverized coal particles in the different outburst interval. These results clearly illustrate that using effective methods to control gas pressure, in-situ stress, and coal strength has an important role in preventing and controlling CGO on coal mining sites.

Experimental Study on Coal and Gas Outburst Risk under Different Water Content Rates in Strong Outburst Coal Seams.

To investigate the alleviation potency of coal seam water infusion on coal and gas outburst, this paper focuses on the Qidong coal mine outburst coal seam, where outburst accidents have occurred many times, and obtains the impact of water content on outburst prediction parameters by studying the features of outburst parameters and gas desorption law under different water content rates. How water content affects outburst was also researched through the use of a self-made outburst simulation test system, and the relationship between water content and outburst intensity and critical gas pressure was studied. It can be concluded that with the rise of water content, the initial velocity of gas diffusion, the gas desorption index of drilling cuttings, and the adsorption constant a decrease, but the firmness coefficient (f) increase, and these indicators are exponentially related to the water content. Meanwhile, as the water content raises, the outburst pressure threshold increases, the outburst intensity gradually decreases, and the less likely outburst occurs. Under 0.5 MPa pressure, as the water content arose from 2.02 to 5.14%, the outburst intensity was significantly weakened, while no outburst occurred as the water content reached to 10.25%. Fitting analysis of the influence curve of outburst parameters and comparing the vital values of outburst prediction indexes finally determined that the water content rate of 5.14% could be used as a key index for water injection measures for coal and gas outburst prevention coal seam in Qidong coal mine no. 9. This research offers a guiding significance for the outburst prevention measures of water infusion in outburst coal seams and gives a feasible scheme for the safe mining of outburst coal mines.

Experimental study on the transporting and crushing effect of gas on coal powder during the develop stage of coal and gas outburst in roadway.

In recent years, coal and gas outburst disasters are still occurring and difficult to prevent, seriously endangering the safety of coal mine production. It is well known that the transporting and crushing of outburst coal is the main pathway of energy dissipation during the coal and gas outburst process. However, a consensus regarding how much gas involves in outburst and affects energy dissipation is still lacking. Quantitative study on the gas effect on migration and fragmentation characteristics of outburst coal in restricted roadway space can improve the energy model and guide the prevention and control of gas outburst. In this paper, an improved visual coal and gas outburst dynamic effect simulation experiment system was used to conduct outburst simulation experiments at different gas pressure conditions. The results showed that the movement of outburst coal in the roadway has experienced various flow patterns. In the initial stage of the outburst, under low gas pressure condition, the motion of the outburst coal was dominated by stratified flow. However, as the gas pressure increases, the initial acceleration increases, and the outburst coal mainly move forward rapidly in the form of plug flow. The average velocity at 0.3, 0.5, and 0.8MPa gas pressure condition were 6.75, 22.22 and 35.81m/s, respectively. Gas also has a crushing effect on outburst coal. With increasing gas pressure, the number of coal powder particles of the same mass increased significantly, and the range of the particle size distribution of the particles decreaed, and the median particle size decreased. As the gas pressure increases, the outburst intensity gradually increases, and the total energy involved in the outburst work also increases. However, the energy dissipation pathways are different. At 0.3MPa, the energy dissipation is dominated by crushing energy, which is about six times the ejection energy. As the gas pressure increased to 0.8MPa, the proportion of the ejection energy gradually increases to about twice that of the crushing energy. Under the experimental conditions, 2.71-13.43% of the adsorbed gas involves in the outburst (AGIO) through rapid desorption, and the proportion increases with increasing gas pressure. This paper improves the energy model of coal and gas outburst, which is applicable to risk assessment and prevention of outburst disasters.

Discussion on Classification of Outburst Coal Seam Based on Outburst Intensity

Discussion on Classification of Outburst Coal Seam Based on Outburst Intensity

Experimental study on the contribution of desorbed gas to the propagation and disaster-causing of coal-gas outbursts

Coal-gas outburst will take a large amount of coal-gas mixture into the coal mining workspace within a short time, and most of the energy in this process is provided by high-pressure gas. To figure out whether desorption gas participates in the process and how much contribution it makes, we performed comparative simulation experiments with adsorptive/non-adsorptive gas. Contributions of desorption gas in outbursts are revealed from the aspects of its propagation and disaster-causing effects. Then, combining the energy equation of outburst process with the large-scale pipeline transportation equation, a method that can accurately work out the energy contribution of desorption gas in outburst experiments is proposed. The results indicate that the desorption gas will promote the propagation of outburst two-phase flow, delay the attenuation of dynamics and strengthen the disaster-causing effects. With the same outburst pressure, the relative outburst intensity of CO2 as outburst gas is 8.08–12.48% higher than that of N2. When the outburst pressure is 0.5 MPa, in the experiment with 1–2.36 mm coal sample and N2, the overpressure attenuation from sensor 1# to 4# is 83.01%, while it is only 63.16% using < 0.25 mm coal sample and CO2. The action duration of positive pressure (ADPP), specific impulse and damage level of outbursts with CO2 are higher than that with N2, and the smaller the particle size of coal sample, the greater the difference. The total outburst energy of coal samples < 0.25 mm is 1.44 ∼ 1.78 times that of 1–2.36 mm coal samples. For coal samples with larger particle size of 1–2.36 mm, the energy contribution rate of desorption gas increased from 35.05% to 48.23%, while the contribution rate of desorption gas exceeded that of free gas for coal samples with particle size of < 0.25 mm, reaching to 55.35 ∼ 59.46%, verifying the key role of desorption gas in outbursts. Findings of this study highlight the importance of quantifying contributions of rapidly desorbed gas towards effective interpretation of outburst disaster-causing mechanisms.

Study on the law of initial gas expansion energy and its feasibility in coal and gas outburst prediction

In order to explore the relationship between IEERG and outburst intensity and verify the feasibility of the former in predicting coal and gas outburst, a series tests with different gases and different gas pressures were conducted on the basis of self-developed coal and gas outburst simulation system and IEERG measuring instrument. The results show that with the increase of gas pressure, the IEERG increases gradually. Under the same gas pressure, the coal has the strongest adsorption capacity for CO2, followed by CH4 and N2. When the IEERG is less than 24.40mJ·g-1, no outburst will occur. When the IEERG is greater than 24.40mJ·g-1, weak outburst will occur. When the IEERG is greater than 34.72mJ·g-1, strong outburst will occur. This shows that the magnitude of IEERG is closely related to the outburst. The larger the IEERG, the greater the possibility of outburst and the greater the intensity of outburst. It is feasible to predict the risk of outburst using IEERG, and it can be quantified.

Gas pressure evolution characteristics of deep true triaxial coal and gas outburst based on acoustic emission monitoring

Coal and gas outburst is one of the geological disasters that seriously threaten the safety of coal mines production. In recent years, with the increase of mining depth, outbursts become frequent. To further explore the occurrence mechanism of deep coal and gas outburst, a self-developed true triaxial coal and gas outburst simulation device was used to simulate the coal and gas outburst at different depths. The results show that with the increase of simulation depth, the critical gas pressure of outburst gradually decreases, and the unit outburst intensity increases sharply. The gas threshold of deep coal and gas outburst is lower. During the incubation and excitation, gas pressure has three special variation rules, namely self-increasing characteristic, stage and instantaneous. In the early incubation, acoustic emission (AE) energy is at a low level, low energy frequency is dominant; in the later incubation, AE energy increases greatly, high energy frequency is dominant. From the perspective of AE energy, a quantitative index that reflects the danger of coal and gas outburst in the incubation is defined, which provides a scientific reference for the prediction and prevention of disasters of coal and gas outburst in deep mining.

Prediction Method of Coal and Gas Outburst Intensity Based on Digital Twin and Deep Learning

Digital twin can well solve complex problems, especially in the case of mechanical failures. Digital twin technology can be applied in 3D IoT smart factories, new smart city construction, smart medical care, digital energy, digital archives, warehousing and logistics visualization and other fields. Deep learning covers a wide range of applications and is extremely common. This paper discusses the application of the two in the risk prediction of coal and gas outburst strength. This paper firstly describes the method of predicting coal and gas outburst intensity. For example, the BP neural network algorithm applied to the prediction of coal and gas outburst intensity in deep learning, the air flow control system model of digital twin for coal mines, and the risk assessment algorithm of coal and gas outburst intensity in coal mines based on grey relational analysis, and various ways to predict risk. And the system model is designed in this paper. Combined with the Formula, this paper describes the process of predicting risk in detail, and then conducts experiments based on digital twin and deep learning to predict coal and gas outburst intensity. In this paper, digital twin is used to systematically design coal and gas outburst intensity prediction, and a neural network prediction model based on optimized quantum gate nodes is established. In this paper, the practical application experiment and result analysis of the optimization algorithm in the coal and gas outburst prediction model are carried out, and the conclusion is drawn. After QGNN is optimized by the sdPSO algorithm, the error is extremely small, only 2.0914, and the specific value of the prediction accuracy in practical applications is as high as 95%. The experimental data verifies the feasibility of digital twin and deep learning technology in the prediction of coal and gas outburst intensity.

Experimental study on intensity and energy evolution of deep coal and gas outburst

Coal and gas outburst is the most serious dynamic disasters in coal mining. The essence of mechanics is the instability and destruction process of coal and rock caused by energy accumulation and release. With mining depth increase, complex geological and stress conditions make coal and gas outburst present new characteristics, which severely restricts the reliability and effectiveness of disaster warning. For this study, the coal and gas outburst tests at different simulation depths were carried out to explore more effective prediction and prevention measures. The results show that a two-phase flow of coal and gas is ejected from the outburst mouth at high speed for 0.6–1.5 s. As the simulation depth increases, both the critical gas pressure and relative outburst intensity decrease, but the unit outburst intensity increases. The deep coal and gas outburst was characteristic of low threshold of gas pressure, easy to trigger and high intensity. The evolution of acoustic emission (AE) energy has experienced “steady-rise-peak” process. The cumulative AE energy in the early incubation is relatively small which is gradually increases at the later incubation. The cumulative AE increases sharply exposed strong outburst risk at the excitation. The propagation of impact force in the roadway has experienced “rise-peak-decrease” process, showing a “crest effect”. The cumulative AE energy increases exponentially with the peak impact force. According to the range of changes in the outburst indicators N1 and N2, the outburst risk is divided into five levels: no risk, low risk, medium risk, high risk and strong risk. A new prediction method for coal and gas outburst based on acoustic emission parameters is proposed, and its applications are discussed.

Influence of coal seam gas pressure on the propagation mechanism of outburst two-phase flow in visual roadway

Coal and gas outbursts are serious disasters that occur during coal mine production. In these instances, the outburst two-phase flow is the main cause of casualties. To investigate the propagation and mechanism responsible for the disaster of the outburst two-phase flow, a visual test system for coal and gas outburst simulation was independently developed. The outburst simulation experiments under different gas pressures were carried out and the propagation process of outburst two-phase flow in a visual roadway was monitored in real time to analyze the propagation mechanism and outburst intensity. The experimental results showed that the first shock wave overpressure reached its peak value immediately after the outburst and the characteristics of turbulent pulse appeared at the front of the outburst cavern, which was followed by one to two successive waves with lower peak values in the negative-pressure region. The flow pattern of pulverized coal observed in the visual roadway included suspended, stratified, dune, and plug flows. The velocity of pulverized coal flow was calculated based on the image method, which can be divided into the acceleration phase, and the acceleration and deceleration cycling phases. When the gas pressure increased from 0.35 MPa to 2.0 MPa, the velocity of pulverized coal flow increased from 34.19 m/s to 71.20 m/s, while they had a nonlinear relationship. The shock wave propagated in the roadway ahead of the pulverized coal flow at supersonic speed, and the velocity of shock wave front was as high as 344.75–370.02 m/s, which was much higher than that of pulverized coal flow. The higher the gas pressure was, the more pulverized coal ejected, and the relative outburst strengths increased from 36.1% to 63.7% with the increase of gas pressure from 0.35 MPa to 2.0 MPa.

The Effects of Large-scale Magnetic Fields on the Model for Repeating Changing-look AGNs

Abstract Periodic outbursts are observed in several changing-look (CL) active galactic nuclei (AGNs). Sniegowska et al. suggested a model to explain the repeating CL in these AGNs, where the periodic outbursts are triggered in a narrow unstable zone between an inner advection-dominated accretion flow and outer thin disk. In this work, we intend to investigate the effects of large-scale magnetic fields on the limit cycle behaviors of CL AGNs. The winds driven by magnetic fields can significantly change the structure of thin disk by taking away the angular momentum and energy of the disk. It is found that the period of outburst in repeating CL AGNs can be substantially reduced by the magnetic fields. Conversely, if we keep the period unchanged, the outburst intensity can be raised by several times. These results can help to explain the observational properties of multiple CL AGNs. Besides the magnetic fields, the effects of transition radius , the width of the transition zone ΔR, and the Shakura–Sunyaev parameter α are also explored in this work.

Prediction Model for Gas Outburst Intensity of Coal Mining Face Based on Improved PSO and LSSVM

For the problems of nonlinearity, uncertainty and low prediction accuracy in the gas outburst prediction of coal mining face, the least squares support vector machine (LSSVM) is proposed to establish the prediction model. Firstly, considering the inertia coefficients as global parameters lacks the ability to improve the solution for the traditional particle swarm optimization (PSO), an improved PSO (IPSO) algorithm is introduced to adjust different inertia weights in updating the particle swarm and solve the fitness to stagnate. Secondly, the penalty factor and kernel function parameter of LSSVM are searched automatically, and the regression accuracy and generalization performance is enhanced by applying IPSO. Finally, to verify the proposed prediction model, the model is applied for gas outburst prediction of Jiuli Hill coal mine in Jiaozuo City, and the results are compared with that of PSO-SVM model, IGA-LSSVM model and BP model. The results show that the relative errors of the proposed model are not greater than 2.7%, and the prediction accuracy is higher than other three prediction models. The IPSO-LSSVM model can be used to predict the intensity of gas outburst of coal mining face effectively.

The Energy Principle of Coal and Gas Outbursts: Experimentally Evaluating the Role of Gas Desorption

Outburst energy is a major factor influencing coal and gas outbursts, albeit its estimation is difficult owing to the lack of amenable means for quantification of gas desorption. In the past decades, determining the mechanism of outbursts is one of the most challenging issues in rock mechanics. In this study, a triaxial coal and gas outburst simulation system was employed to perform simulated experiments using He (to rule out the influence from gas ad-desorption), N2, and CO2. This facilitated understanding of the energy principle underlying the said outbursts and evaluation of the effects of gas desorption on outburst development. Results of this study indicate that outburst energy and energy consumption are influenced by several factors, including outburst pressure, outburst intensity, ejection distance, and particle size of ejected coal. Among these, gas desorption demonstrates the greatest influence when performing controlled tests (using He). Considering the effects of gas desorption, the total outburst energy can be increased by 1.35–2.95 times, thereby causing an enormous increase in the destructive potential of outbursts. Additionally, values of the coal crushing and transport energies can be enhanced by the order of 118.9–206.6% and 157.8–406.6%, respectively, thereby resulting in a stronger conveying capacity of outburst coal–gas flow along with severe coal fragmentation. A further analysis of the energy distribution indicated that in the development stage, gas desorbed from coal acts as the force driving coal transport, whereas free gas energy is mainly consumed during coal crushing. Findings of this study highlight the importance of quantifying contributions of coal gas towards effective interpretation of outburst-causing mechanisms.

Experimental Study of Coal–Gas Outburst: Insights from Coal–Rock Structure, Gas Pressure and Adsorptivity

Coal–gas outburst is a complex dynamic phenomenon in underground coal mines that has occurred frequently over the past 150 years. This phenomenon has seriously restricted the efficient development of coal resources and it poses a great threat to global energy security. Physical simulation experiments under different conditions that considered the coal–rock combination structure and gas adsorptivity were carried out by using a true triaxial coal–gas outburst experimental system, and the experiments controlled for the type of adsorbable gas, the presence (or absence) of a roof and the gas pressure. The influence of the coal–rock structure and gas adsorptivity on the disaster occurrence conditions and dynamic response characteristics was discussed, and the gas–solid-coupling disaster-inducing mechanisms of coal–gas outburst under unloading were obtained. The results show that outburst pulverized coal does not present an obvious sorting performance under the experimental conditions of this work. All the outburst holes are characterized by small openings and large cavities. Coal walls around the holes are damaged by spallation, and the strength of the outburst holes is low, but relatively stable. Stronger gas adsorptivity and greater gas pressure correspond to more intense outburst dynamic effects. Moreover, greater outburst intensity corresponds to more obvious coal spallation characteristics. Whether there is roof or not has no significant effect on the sweeping and handling of thrown pulverized coal. Compared with the condition without roof, the existence of a roof will promote an increase in the outburst intensity and more obvious spallation damage of the outburst coal. The coal–gas outburst process includes four stages: outburst occurrence, rapid development, deceleration development and outburst termination. The research results have certain guiding significance for studies on the mechanism of coal–gas outburst.

Experimental investigations of stress‐gas pressure evolution rules of coal and gas outburst: A case study in Dingji coal mine, China

AbstractCoal and gas outburst is a potentially fatal risk during the mining of gassy coal seams, which seriously threatens the safe mining of collieries. To understand the outburst mechanism and evolution rules, a new apparatus (LSTT) was developed to conduct simulated experiment. In the context of an outburst accident in Dingji coal mine, the authors launched an authentic outburst experiment to replay the outburst accident. Experimental apparatus, similar criterion, coal‐like materials and gas sources, and experimental design were discussed systematically in this paper. Experimentally, the study analyzed the geo‐stress has significant influence on the outburst evolution. At the driving face, the stress concentration possibly caused gas outburst, under the influence of mining‐induced stress. After the outburst occurred, the stress balance of the coal changed, resulting in the instability of the coal. Furthermore, the elastic energy, gas enthalpy, and gravitational potential energy were released rapidly. The experimental result stated that outburst coal has the sorting characteristics, in line with the field outburst law. The intensity prediction model has been built based on the energy model. Moreover, the factors that impact outburst intensity were analyzed. In the process of coal and gas outburst, the gas enthalpy of gas and the elastic potential of coal are the main energy sources. This study provides guidance for the development of the outburst mechanism and outburst mine management.

Prediction of coal and gas outburst intensity based on LLE-FOA-BP model

Prediction of coal and gas outburst intensity based on LLE-FOA-BP model

Coal and gas outburst risk prediction based on the F-SPA model

ABSTRACT As the depth of coal mining is gradually increased in China, the intensity of related coal and gas outbursts will become ever-greater. Accurate forecasting of coal and gas outburst is the key to preventing and controlling such incidents. This study uses gray relational analysis (GRA) to identify the four main geological and environmental indicators of coal and gas outburst risk based on the characteristics of the factors influencing coal and gas outburst and their relationships with outburst strength. A Fuzzy SPA (F-SPA) model was constructed using set pair analysis and the coupled weighting method, and coal and gas outburst intensity level was predicted for 25 locations in coal mine No. 8 in the Pingdingshan mining area using the F-SPA model and applying a confidence criterion. The forecast results were compared with those derived using three other methods as well as against actual outbursts that have occurred at those locations. The results of this comparison show that the method proposed in this study has a forecast accuracy of up to 96%. The reliability of the prediction model is verified by error analysis. This case study demonstrates the reliability of the proposed method and provides a new tool for the prevention and control of coal and gas outburst hazards.

A Study on the Energy Condition and Quantitative Analysis of the Occurrence of a Coal and Gas Outburst

With mining depths increasing, coal and gas outburst disasters are becoming more and more serious and complicated, which directly restricts the production efficiency of coal mines. In order to study the rules of energy dissipation during the occurrence of a coal and gas outburst based on the occurrence mechanisms, a simulation experiment of a coal and gas outburst with a ground stress of 16 MPa and a gas pressure of 0.5 MPa was carried out using a self‐developed large‐scale coal and gas outburst simulation experimental system. A quantitative analysis was given based on the energy model. The results showed the following: (1) In the process of the coal and gas outburst, the main energy source originated from the elastic potential energy of the coal body and the gas internal energy. The main energy loss was used for coal crushing and throwing. (2) The outburst coal sample in this experiment had a mass of 18.094 kg, and the relative outburst intensity was 1.21%. Additionally, the farthest throwing distance of the outburst coal samples was 3.3 m away from the outburst hole wall. The distribution of the outburst coal sample decreased along the roadway, and the proportion of the coal sample grain size in each area first decreased and then increased with the decrease of the grain size. The coal samples with a grain size less than 0.2 mm after the outburst accounted for 6.34% of the mass of the total coal samples. (3) The elastic potential energy of the coal body accounted for 0.34% of the total outburst energy, while the gas internal energy accounted for 99.66%. It was verified that gas internal energy was the key energy source for the coal and gas outburst, and this internal energy was two orders of magnitude more than the elastic potential energy, playing a leading role in the outburst process. After the outburst initiation, most of the energy was consumed in coal crushing, which was in the same order of magnitude as the gas internal energy. Moreover, the energy losses due to friction, vibration, and sound during the outburst process comprised no more than 10% of the total energy. The research results can provide certain guidance for clarifying the mechanism of a coal and gas outburst and the quantitative analysis of outburst energy.

Gas Release Characteristics in Coal under Different Stresses and Their Impact on Outbursts

The impact mechanism of in situ stress on outbursts plays a key role in the prevention of outbursts during deep coal mining. The in situ stress may influence the outburst by affecting the gas release intensity according to theoretical analysis, but none of the existing studies have taken into consideration this perspective. To explore whether the influence of in situ stress on gas release in coal is an important reason for stress-induced outbursts, experiments on gas release in coal under different axial stresses and on exposure-induced outbursts with different gases were conducted to respectively study the influence of in situ stress on gas release and the impact of gas release on outburst. The results show that with the increase of stress, the methane release intensity rises by 1~2.4 times and shows an obvious periodicity due to different degrees of fracture development. A small increase in gas release intensity can lead to huge increase in the outburst intensity based on an energy analysis of the outburst experiments, indicating that the gas release intensity is a sensitive physical quantity that influences outbursts. The differences in gas release in coal with different stresses will result in differences in the outburst results based on data from the two experiments, proving that the change in gas release intensity during variations of in situ stress is an important factor for in situ stress-induced outbursts. The research achievements can enrich the impact mechanism of in situ stress on outbursts.