Despite consistent annual growth in China's coalbed methane (CBM) extraction output, its utilization efficiency remains suboptimal due to the declining efficiency of extraction boreholes. To address this challenge, this study developed a novel fracture sealing material (FSM), characterized by low viscosity, micro-expansion, controlled gel time, and appropriate strength for application via secondary grouting. Single-factor experiments were conducted to analyze the influence of the water-to-material (W/M) ratio and the dosage of phenol-formaldehyde (PF), crosslinker, and foaming agent on FSM's properties, including apparent viscosity, compressive strength, gel time, and expansion rate. Subsequently, Response Surface Methodology (RSM) was implemented to investigate multifactorial interaction effects. Quadratic regression models were established to optimize the compositional proportions, which demonstrated high predictive accuracy, with relative errors all below 5 %. Field tests demonstrated that, in comparison with traditional cement mortar, boreholes treated with immediate FSM secondary grouting in Test Group I exhibited a 32.32 % increase in average methane concentration, maintaining high levels of 56.84 %-64.62 % during the subsequent extraction stage. In Test Group II, where FSM grouting was implemented following a 30-day period of borehole extraction, the methane concentration increased instantaneously by 42.83 %, representing an 11.35 % increase compared to the pre-grouting concentration. The findings indicate that the FSM exhibits superior performance in sealing multiscale fractures around boreholes, which is an effective remedy for mitigating concentration decay and prolonging borehole lifespan, thereby enhancing overall CBM extraction efficiency.

This study investigates the chain reaction mechanisms of active groups during low-temperature coal oxidation using FTIR spectroscopy and Materials Studio simulations. Hydroxyl, methyl, carbonyl, and carboxyl groups were identified as key reactive species. FTIR analysis revealed that -OH oxidizes to form H2O between 30 and 90 degrees C, while oxygen-containing groups remained stable initially and increased significantly in later stages. Aliphatic hydrocarbon side chains were oxidized to generate -CH3/-CH2, which were further consumed to produce hydrocarbon gases. Aromatic hydrocarbons showed minimal reactivity at low temperatures. Reactivity analysis demonstrated distinct trends: individual groups followed -CHO > -COOH > -CH3, whereas within the coal molecular structure, the order shifted to -COOH > -CH3 > -CHO. Simulations of oxidation pathways identified the key intermediates and energy barriers for CO/CO2 formation. Results indicated that functional group reactivity depends on nucleophilic reaction sites rather than energy gap values, with temperature predominantly enhancing product formation over transition state activation.The chain reaction of reactive groups in coal provides theoretical support for understanding the coal-oxygen interaction mechanism and guides efforts to curb spontaneous coal combustion.

Microseisms in mining engineering may not only damage the structure of mines, but also interfere with their production activities and induce other geological disasters. Therefore, accurately distinguishing micro-seismicity in mining engineering is of great significance for ensuring mine safety and preventing geological disasters. To distinguish microseisms in mining engineering, a signal denoising method grounded on variational mode decomposition (VMD) algorithm and permutation entropy was studied and designed, and sparrow search algorithm was introduced to optimise the parameters of VMD algorithm. High-quality input data foundation for subsequent micro-seismic resolution models was provided through this denoising method. Subsequently, a micro-seismic resolution model combining transformer and convolutional neural network was developed, which utilises transformer to focus on important information and obtains feature information through depthwise separable convolution. The findings denoted that the designed denoising method achieved maximum signal-to-noise ratios of 33.142 dB, 34.021 dB and 33.743 dB on simulated signals from Blocks, Doppler and Heavyisine, respectively, all of which were higher than the comparison method. The average root mean square error of this method in practical applications was 3.088 × 10 −6 . The accuracy and maximum root mean square error of the micro-seismic resolution model were 97.54% and 2.95 × 10 −6 , respectively. The average time consumption and F1 score were 7.12 ms and 0.9456, which were better than the comparison model. On the training set, the model correctly identified 491, 497, 493, 508 and 498 micro-seismic information, rubber hammer vibration information, iron hammer vibration information, excavation vibration information and blasting vibration information, respectively, which were closer to the true values. The designed noise reduction method and resolution model have good effects and can provide accurate signal processing and analysis tools for micro-seismic resolution in mining engineering. The novelty of the research lies in the combination of micro-seismic signal denoising and micro-seismic identification resolution, which avoids the uncertainty caused by manually setting parameters and comprehensively improves the resolution accuracy of micro-seismic research in mining engineering, surpassing previous research efforts in micro-seismic monitoring accuracy in mining engineering.

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Innovative and entrepreneurial talents is the main driving force for local universities to promote the smooth development of the society, and is also a key factor in improving the employment rate of graduates. Using the example of undergraduate safety engineering students, this study analyzed the important role that the innovative and entrepreneurial talents of students play in the society development. The current problems in teaching are analyzed in terms of theoretical teaching, practical teaching, lack of practical ability of the teaching staff and assessment methods. In order to solve the above problems, this study constructed a multidisciplinary cross-fertilization teaching system in theoretical and practical teaching, and proposes a diversified evaluation method, and applying them to teaching practice with some success. To cultivate talents with innovative thinking and skills, and to provide a reference for the cultivation of high-quality applied talents in China's security engineering profession.

“Mine Ventilation and Safety” is a fundamental course for safety engineering students. However, the current teaching mode has several shortcomings, including low student motivation, an irrational teaching mode, inefficient teacher-student interaction, and unreasonable process assessment. These issues fail to meet the requirements of the information age for undergraduate engineering education objectives. The course “Mine Ventilation and Safety” will be reformed based on the development of the Internet and the widespread application of information technology. The basic knowledge of the course will be reorganized, and the teaching content will be reconstructed. The implementation of a network information platform to create a “smart classroom” can enhance students' learning initiative, improve teacher-student interaction efficiency, and enhance students' ability to solve practical problems. This can lead to the cultivation of high-quality, professional, and skilled individuals.

Enhanced coalbed methane (ECBM) recovery by gas injection is regarded as a feasible method for ECBM recovery. To investigate the mechanism of CH4 displacement by N2 injection, a series of physical experiments were conducted in the laboratory under different N2 injection pressures. The experimental results showed a continuous increase in the N2 volume fraction and a decrease in the CH4 volume fraction with the N2 injection pressure. The CH4 displacement efficiency increases rapidly in the initial stage and then gradually stabilizes. Given the effect of matrix shrinkage and effective stress on coal permeability, a dynamic multi-field coupling model of ECBM recovery by N2 injection (N2-ECBM) was proposed in this work. Then, numerical simulations were implemented by the coupling model to analyze the key factors affecting coal permeability, N2 injection pressure and CH4 pressure during the N2-ECBM process. Furthermore, the Response Surface Methodology (RSM) was used to investigate the interactions of multiple factors, the results reveal that an increase in one factor would weaken the influence of another factor. In addition, a RSM regression model was obtained and verified by the experimental data, with a well-fitting outcomes. Therefore, the RSM model can be used in practical engineering applications to optimize specific extraction parameters for ECBM recovery at minimum cost in a limited extraction period.

在"四新"建设背景下,物理化学教学秉承"以学生为中心,以目标为导向"的教学理念,采用雨课堂与三课融合的线上线下混合式教学模式;以学生的"知识、能力、素质"协同发展为目标,把教学内容整合成基础知识、实际应用、内容拓展三大模块;针对不同的教学内容采用适用的教学方法,并通过绘制思维导图、撰写小组报告、课程论文、文献研读报告等形式对教学评价形式进行改革,构建系统的知识体系,培养学生的自学能力、创新意识、科学思维方法和团队协作精神.

《通风安全学》作为安全工程专业本科教育的核心课程,其教学质量直接关乎现代化煤炭经济体系的专业人才培养.通过剖析传统教学模式下《通风安全学》课程教学与人才培养现状,针对教师队伍、实践教学、考核模式、思政元素方面存在的问题,提出"以学生为中心、以实践为导向、化思政为内涵"的《通风安全学》教学实践多元化改革研究.通过多重并举的改革措施,如健全教师队伍的考评机制,促进教学实践的有机结合,增加过程考核等,加强马克思主义立场观念的思政教学,显著改善了教学实践效果,激发了学生学习主动性,对新时代矿山安全专业人才培养具有重要的现实意义.

This study aimed to further explore the adsorption properties of different gases (CO2, O2, and CH4) on the coking coal surface by establishing a molecular model. Changes in the absolute adsorption capacity and the isosteric heat of adsorption of gases under different temperatures, pressures, and compositions were simulated using grand canonical Monte Carlo (GCMC) and molecular dynamics simulations. Interaction energy and energy distribution were used to analyze the adsorption behavior of gases, and the diffusion properties were investigated using the diffusion coefficient and diffusion activation energy. The absolute adsorption results fit well with the Langmuir–Freundlich model. The absolute adsorption capacity had a significant positive correlation with pressure and the corresponding mole fraction, and a significant negative correlation with temperature. The competitiveness, based on binary adsorption selectivity, was in the order of CO2 > O2 > CH4. The isosteric heat of adsorption of CH4 was slightly higher than that of O2, and that of CO2 was 1.49–1.64 times that of O2 and CH4. The isosteric heat of the adsorption of gases was also barely influenced by temperature and pressure. The interaction energy between CO2 and coal was greater than that of O2 or CH4, but the high pressure and high content were not conducive to the adsorption of O2 by CO2. The preferred adsorption site for CO2 was stronger than that for O2 and CH4, and its peak value negatively correlated with the molar fraction. The diffusion coefficient for single component gases initially increased and then decreased with increased pressure, showing a positive correlation with temperature. A close inverse correlation existed between diffusion activation energy and pressure. These results revealed the microscopic adsorption and diffusion regularities of CO2, O2, and CH4 in the coal model, indicating great significance in accurately predicting coal fires.

To construct the macromolecular model of gas coal in the Huainan mining area, 13C nuclear magnetic resonance spectroscopy (13C-NMR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) tests were used to analyze the microstructure characteristics of coal including the aromatic ring type, the linkage mode, and the chemical bonding composition. The model was simulated and optimized by molecular mechanics (MM) and molecular dynamics (MD). The experimental results showed that the coal macromolecular formula in the Huainan mine was expressed as C181H150O9N3. The aromatic ring was dominated by anthracene and phenanthrene. Aliphatic carbon mainly existed in the form of methylene and methine. The oxygen atoms existed in the form of ether−oxygen bonds. The ratio of pyridine nitrogen to pyrrolic nitrogen was 2:1. The molecular simulation results showed the π−π interaction between the aromatic lamellae within the molecule. The van der Waals energy was the major factor of coal molecular structure stability and energy change. The results of the calculated 13C-NMR carbon spectrum and density simulation agreed well with the experimental results. The study provides a scientific and reasonable method for coal macromolecular model prediction and theoretical support for coal spontaneous combustion prevention technology.

A new cement-based sealing material, which used Portland cement (PC) as a raw material and supplemented several gel components, such as accelerant, alkali activator, suspension agent, expansion agent, reinforcing agent, was prepared in this work. The effects of these components on the fluidity, setting time, and expansion rate of these sealing materials were investigated by an orthogonal test. The results show that the water-cement ratio and the reinforcing agent content, the accelerant content and the water-cement ratio, and the expansion agent content and the accelerant content are the most important influencing factors on fluidity, setting time, and expansion rate, respectively. In addition, the regression models and response surfaces of the factors were established using a multiple linear regression method. By this means, the influences of the two main factors on each performance of this sealing material were accurately and intuitively reflected for obtaining the optimal value in the optimization area. The results indicate that the sealing materials possess the best performances when the water-cement ratio is 1.1, the accelerant content is 50%, the expansion agent content is 0.1%, and the reinforcing agent content is 3%, which is corresponding to a fluidity of 360-380 mm, an initial (final) setting time of 60 (80)-80 (100) min, and an expansion rate of 2-12%. Furthermore, the microstructures of the optimized sealing material also reveal that the main hydration products of PC are transformed from layered Ca(OH)2 crystals into fine needle-like AFt crystals and C-S-H gels by the promotion effect of the optimizing ratio, thus leading to a more compact structure of optimized cement-based sealing materials.

Grouting is the most effective approach for underground broken coal treatment. Traditional cement (TC) has difficulty achieving an ideal grouting anti–seepage and reinforcement effect due to the hydrophobic property of coal. This work developed an interfacial porosity model given Gibbs free energy changes during the droplet spreading on coal surface. And the key factors that affect the interface bonding behaviors were analyzed by means of model calculation. Accordingly, four types of wetting agents were selected to modify the coal hydrophobic property via Fourier Transform Infrared Reflection, pulverized coal settling, and contact angle tests. Results showed that the anionic wetting agent WA–2 exhibited the greatest improvement on the coal wettability, and its addition resulted in a fine promotion effect at 0.5%. Furthermore, grouting simulation experiments on broken coal were conducted to compare the actual grouting effects of the modified and traditional cement. Nuclear Magnetic Resonance results reveal that the porosity of the grouted coal specimens by modified cement (MC) was less than that of TC. Moreover, the quantities of mesopore and macropore were remarkably decreased by 85.76% and 96.69%, respectively. Scanning Electron Microscopy results also presented a superior bonding performance between the MC and the injected coal, which indicates that the surface wettability of coal can be improved by the MC, thereby weakening the coal hydrophobic effect and promoting ion diffusion during the cement hydration process. In effect, resulting in the enhancement of the occlusion force and bonding strength of the grout–coal interface. The finding demonstrates that the wettability modification of cement grout contributes to improving the microstructure of the grout–coal interface, substantially ameliorating the grouting quality and prolonging the stability of broken coal on the macro–level.

《工程化学》是工科院校非化学类专业一门重要的基础课程,开设专业广泛,是一门很好的课程思政建设课程.文章以此课程为依托,将思想政治教育工作贯穿教学全过程,挖掘不同的思政元素,融入不同的教学手法,对《工程化学》"课程思政"的教学改革进行了一定的探索与实践.并通过问卷调查来对思政内容融入效果进行了评价,并对未来如何进一步提高"课程思政"效果指明了方向.

In order to study the influence of moisture intrusion on crack propagation and failure mode of loaded coal, uniaxial compression tests and acoustic emission monitoring of coal with different moisture contents are carried out. The stress-strain characteristics, macroscopic failure patterns and change law of cumulative ringing counts of loaded coal with different moisture contents are compared and analyzed. The results of uniaxial compression tests show that with the increase of moisture content, the uniaxial compressive strength and elastic modulus of coal decrease continuously. The stress drop rate of coal gradually slows down in the post-peak stage. The macroscopic failure mode of coal samples changes from typical brittle failure to shear-tension combined failure. The acoustic emission monitoring results show that the cumulative ringing counts decreases with the increase of coal moisture content. The cumulative ringing counts curve's slope increases correspondingly, indicating that moisture intrusion can reduce the energy release when the coal cracks develop. However, the moisture intrusion aggravates the internal structure damage of coal. The results show that the water intrusion weakens the friction between crystal particles on the surface of cracks to some extent, and increases the possibility of coal sliding failure. At the same time, the water intrusion also reduces the surface active energy of the coal, resulting in a significant increase in the number of cracks generated during the loading process of the coal sample. This leads to a large drop in the macroscopic mechanical strength of the coal.

In order to study the effect of liquid-solid expansion phase change on coal permeability enhancement under thermal environment, based on the experiment of increasing the permeability of coal by thermal storage phase change, the characteristics of coal permeability and T2 relaxation time spectrum changes under the effect of thermal storage phase change are obtained, and the effects of thermal storage phase change on coal permeability and pore structure were analyzed. The research results show that the maximum increase in coal permeability under the effect of thermal storage phase change reaches 150.8%, the thermal environment provided by the thermal storage phase change can promote the effect of phase change expansion on the increase of the coal permeability. The peak of the coal body T2 relaxation time between 10 ms and 50 ms and about 100 ms rises relatively higher, the increase is 15.36% and 18.03%, and the maximum increase of the T2 value between the two peaks is 47.11%. The thermal storage phase change mainly increases the permeability of coal by increasing the number of medium and large pores and cracks, and the structure connectivity between the two.

Underground oil and gas pipelines are usually expected to be long-lasting. Corrosion of these steel pipelines may cause structural failures that significantly threaten life and cause environmental hazards. Therefore, developing a reliable approach to estimate soil corrosivity is important for designing a targeted anti-corrosion structure and performing risk assessment. In this study, an extension-based approach is proposed to evaluate soil corrosivity based on the following seven soil properties: redox potential, soil resistivity, pH, pipe-to-soil potential, water content, Chloride (Cl−) concentration, and salt content. Specifically, the soil was classified into five corrosivity levels, and the classic domain element, joint domain element, and element to be evaluated were established by the matter-element theory. Then, the corrosivity level was determined based on the maximum correlation degree of the multi-index to the five levels, and the final classification was obtained from the eigenvalues of the grade variables. Finally, the case study was examined to validate the application of the approach, and the results were compared to the method of buried metal specimens, which was used as a criterion. The present approach, which provided a more detailed classification, was demonstrated to be a superior choice for classifying soil corrosivity levels.

为研究化工企业火灾爆炸事故的主要人为因素,以63起火灾爆炸事故案例为样本,构建人为因素分析与分类系统(HFACS)模型,进行火灾爆炸事故人为因素分类统计与分析,并利用卡方检验和比值比分析HFACS模型上下层级间的因果关系.结果表明:HFACS模型中上下层级人为因素间存在显著的因果关系,层级1中的"不良的组织氛围"及"组织过程漏洞"和层级2中"监督不充分"在HFACS模型中可以显著增大事故发生的可能性,且"资源管理漏洞"、"不良的组织氛围"、"组织过程漏洞"→"监督不充分"→"人员因素"→"违规"是引发事故的关键路径,并根据HFACS模型中引发事故的关键路径及其人为因素的主要表现形式,提出针对性的化工企业火灾爆炸事故预防措施.

为准确地判定岩溶隧道开挖过程中的塌方风险,应用未确知测度理论,建立塌方风险预警模型.首先,根据隧道塌方的影响因素分析,建立隧道开挖塌方风险预警的三级指标体系,选取年平均降雨量、单轴抗压强度、围岩渗透系数、岩溶直径、隧道埋深、开挖工法等18项指标作为预警指标,包括9个定量指标和9个定性指标,划分5个预警等级.其次,构建各定量指标和定性指标的分级标准,构造各定量指标的未确知测度函数,利用信息熵理论计算各指标权重,依照置信度识别准则进行塌方风险预警等级判定.最后,选取某岩溶区隧道工程为实例,验证该预警模型的适用性.结果 表明:该隧道开挖塌方风险预警等级为Ⅲ级,即为橙色预警等级,该结果与实际情况较吻合,说明隧道开挖过程中存在较大坍塌危险,隧道内应配备专职地质灾害安全员,并对地质灾害进行不间断监测.该预警方法能够为提前采取塌方风险防范措施和编制应急预案提供理论依据,也为隧道塌方风险预警提供新的思路.