Search

In the mining process of working face, the additional stress generated by the fault changes the law of roadway deformation and failure as well as the law of overburden failure. Aiming at the influence of the fault in the mining process of working face, this study introduced the geological strength index (GSI) to analyze the stress distribution in the elastic-plastic zone of the surrounding rock of the roadway. And similar experiments under different engineering backgrounds were combined to study the characteristics of overburden movement and stress evolution. Based on the conclusions obtained, the roadway support scheme was designed. This study shows that, compared with ordinary mining, through-the-fault mining causes slippage and dislocation of the fault, the load of the overburden is transferred to both sides of the fault, and the stress near the fault accumulates abnormally. The "three zones" characteristics of the overburden movement disappear, the subsidence pattern is changed from "trapezoid" to "inverted triangle", and the influence distance of the advanced mining stress on the working face is extended from 20m to 30m. The instability range of roadway surrounding rock is exponentially correlated with the rupture degree of the surrounding rock. Through the introduction of GSI, the critical instability range of roadway surrounding rock is deduced to be 2.32m. According to the conclusion, the bolt length and roadway reinforced support length are redesigned. Engineering application shows that the deformation rate of the roadway within 60 days is controlled below 0.1~0.5mm/d, the deformation amount is controlled within 150mm, and the roadway deformation is controlled, which generally meets the requirements of use. The research results provide guidance and reference for similar roadway support., Competing Interests: The author(s) declare no competing financial interests.

Measurement while drilling is an important part of the intelligent development of coal mines. The main purpose of this paper is to comprehensively analyze the response characteristics of borehole drilling parameters and find a better method to predict rock mechanical properties based on drilling parameters. Firstly, six concrete blocks and multiple specimens were prepared with different material ratios. Next, the concrete specimens were tested for mechanical properties in the laboratory. Meanwhile, the displacement, rotation speed, torque, and sound pressure level (SPL) were observed during the drilling of the concrete blocks. Finally, the response characteristics of drilling parameters such as rotation speed, rate of penetration (ROP), torque, and SPL were analyzed. Besides, multiple prediction models of rock mechanical parameters were obtained by data analysis. The research results indicate that the drilling process can be classified into the initial stage of drilling (fast speed) and the steady stage of drilling (slow speed). The torque work ratio accounts for more than 99%, which increases with the increase in rock strength. The penetration depth per revolution and torque work ratio are significantly related to rock uniaxial compressive strength, Brazilian tensile strength, cohesion, and elastic modulus. The ROP is the best choice for estimating rock mechanical parameters. This research provides an important reference for laboratory rock mechanics parameter testing and geological features detection based on drilling parameters., Competing Interests: The authors have declared that no competing interests exist.

To investigate the influence of bedding structure and different loading rates on the dynamic fracture characteristics and energy dissipation of Datong coal, a split Hopkinson bar was used to obtain the fracture characteristics of coal samples with different bedding angles. The process of crack initiation and propagation in Datong coal was recorded by the high-speed camera. The formula for the model I fracture toughness of the transversely isotropic material is obtained on the basis of the finite element method (FEM) together with the J-integral. By comparing the incident energy, absorbed energy, fracture energy and residual kinetic energy of Datong coal samples under various impact speeds, the energy dissipation characteristics during the dynamic fracture process of coal considering the bedding structure is acquired. The experimental results indicate that the fracture pattern of notched semi-circular bending (NSCB) Datong coal is tensile failure. After splitting into two parts, the coal sample rotates approximately uniformly around the contact point between the sample and the incident rod. The dynamic fracture toughness is 3.52~8.64 times of the quasi-static fracture toughness for Datong coal. Dynamic fracture toughness increases with increasing impact velocity, and the effect of bedding angle on fracture toughness then decreases. In addition, the residual kinetic energy of coal samples with the same bedding angle increases with the increase of impact speed. The energy utilization rate decreases continuously, and the overall dispersion of statistical data decreases gradually. In rock fragmentation engineering, the optimum loading condition is low-speed loading regardless of energy utilization efficiency or fracture toughness. These conclusions may have significant implications for the optimization of hydraulic fracturing process in coal mass and the further understanding of crack propagation mechanisms in coalbed methane extraction (CME). The anisotropic effect of coal should be fully considered in both these cases., Competing Interests: The authors have declared that no competing interests exist.

The decision matrix method is preferred as a measure of risk evaluation considering the risk value obtained by two risk factors such as the likelihood and severity of a hazard. However, it has some deficiencies since a crisp risk score is assigned for likelihood and severity. In this article, a fuzzy logic-based safety evaluation method to enhance the risk assessment process is introduced to overcome the uncertainties encountered in the classical decision matrix risk assessment method. The proposed method is a more realistic evaluation of the risks which may be available in mechanized coal mines in Turkey. In this way, risky situations and operations in mechanized underground coal mines have been determined by expert knowledge and engineering judgement in linguistic forms. Thus, such an evaluation will be a valuable guide for coal mines in which fully mechanized coal production is expected in the near future.

Purpose of Review: To review the impact of coal mining and resurgence of coal workers' pneumoconiosis (CWP) in 21st century and effect of ambient air pollution on lung function., Recent Findings: At the beginning of 21st century, statistics by National Institute for Occupational Safety and Health showed a steep rise in pneumoconiosis. This was followed by numerous epidemiologic and pathologic studies that confirmed increasing CWP prevalence as well as disease in younger miners and those with a shorter mining tenure. Recent studies have demonstrated that poor dust control in mines, a relative shift in composition of the coal mine dust, small sized mines and increase in surface mining are all possible contributors to this resurgence. There is also growing literature evaluating the effects of worsening air pollution on health, including decreasing lung function and development of emphysema, worsening quality of life measures and lung cancer., Summary: This irreversible but preventable disease currently haunts approximately 60 000 miners across United States and millions across the world. Its resurgence despite the strict dust regulations is a setback from the public health standpoint. The continued reliance on coal for energy will continue to place coal miners at danger of developing disease as well as the world.

Background: Investigation of the safety management efficiency in a coal mine aims to improve its safety management level thus ensuring coal mining safety. However, the safety management efficiency is affected by many factors especially for those coal mines operated underground. Furthermore, the constraint factors that are difficult to be identified and eliminated may impede safety management efficiency., Objective: This work aims to explore the constraints affecting safety management efficiency through a mathematical model accompanied by some effective measures guided by the theory of constraint (TOC)., Methods: An index system for coal mining safety management efficiency (CMSME) is first established. Then a mathematical model roughly identifying the constraint factors is constructed. The principle of the proposed model is a comparison with the changes of the ratio of integrated CMSME and the ratio of each impact factor over a certain period. Thus, a constraint factor may be one whose ratio changes at a slower rate than that of the integrated CMSME. Following this, some measures are adopted to identify one, or more, real constraints. Finally, the constraints may be broken by internal, or external, means., Results: A case study from Quandian coal mine verified the proposed method: the constraints affecting CMSME could be identified and broken through during the production. This research currently is applied to coal mining activities in a few coal mines, and it will be widely used in the future., Conclusions: This paper provides a novel method investigating the constraints affecting CMSME and breaking through them. The case study shows that breaking through constraints during the production is beneficial to CMSME. Furthermore, a coal mine with a high CMSME index may still, at some time, have one, or more, bottleneck constraints.

This study aimed to provide a greater understanding of the systemic factors involved in coal mine accidents and to examine the relationships between the contributing factors across all levels of the system. Ninety-four extraordinarily major coal mine accidents that occurred in China from 1997 to 2011 were analyzed using the human factors analysis and classification system (HFACS). The empirical results showed that the frequencies of unsafe behaviors, inadequate regulation and failure to correct hidden dangers were the highest among five levels, 14 categories and 48 indicators, respectively. The odds ratio technique was applied to quantitatively examine the relationships between contributing factors. Various statistically significant associations were discovered and should receive greater attention in future attempts to develop accident measures. In addition, several strategies concerning the main contributing factors and routes to failure are proposed to prevent accidents from reoccurring in an organization.

This paper intends to use data to verify the correlation between safety culture, safety management system and safety knowledge, safety awareness, and safety habits, which is the correlation between the various parts of the behavior safety "2-4" model. Due to data limitations, the results are limited to the study of safety culture related relationships in coal mining enterprises. This paper first designed a questionnaire containing 30 questions, of which 1⁻5 questions represent safety culture, 6⁻22 questions represent safety management system, and 23⁻30 questions represent safety knowledge, safety awareness and safety habits. Employees of 27 coal mining enterprises in Shandong, Henan, Hunan and other places in China were surveyed and sampled by stratified random sampling, and 1514 valid questionnaires were obtained. After item analysis and correlation analysis, and it was found that, within the data of 1514 questionnaires, the item total correlation coefficients of questions 6, 9, 19 and 28 were all less than 0.2, indicating that the identification degree of these four items was poor, which was deleted. Using the data analysis of the remaining 26 questions in the questionnaire, it was found that the relationship between safety culture and the safety management system, the safety management system and safety knowledge, and safety awareness and safety habits is moderately related; safety culture and safety knowledge, safety awareness and safety habits are weakly related. The conclusion shows that the safety culture directly affects the safety management system; the safety management system directly affects the safety knowledge, safety awareness and safety habits; the safety culture indirectly affects safety knowledge, safety awareness and safety habits. However, why the expected strong correlation is not achieved, and whether the same conclusion can be obtained if the data scale is expanded or other types of enterprises are added for questionnaire measurement, these are questions worthy of further study, which is also the author's next research content.

Spontaneous combustion of coal is one of the major hazards threatening production safety during longwall mining. Mining-induced voids, which provide passages for air leakage, are the key factor triggering spontaneous combustion of coal in longwall goafs. In this study, a comprehensive method, which combined pressure balance, grouting injection, and filling fissures, was proposed to prevent spontaneous combustion of coal in longwall goafs with complex air leakage. Field engineering practice was carried out in Sitai Coal Mine in China. The results demonstrated that with the application of the proposed method, in the working face, the concentration of CO was decreased from 31ppm to 0 and the air leakage quantity was decreased from 261 to below 80 m3min-1. The gas samples analysis from the gob areas also indicated that concentrations of O2 and CO were successively decreased, indicating that the risk of spontaneous combustion of coal in goafs was eliminated. The above mentioned analysis indicates that, the method proposed in this study is useful and efficient. Successful application of this technology could provide reference for the treatment of other coal mines., Competing Interests: This commercial affiliation (Sitai Coal Mine) along with any other relevant declarations relating to employment, consultancy, patents, products in development, or marketed products, etc., does not alter our adherence to PLOS ONE policies on sharing data and materials.

During coal surface mining, several activities such as drilling, blasting, loading, and transport produce large quantities of particulate matter (PM) that is directly emitted into the atmosphere. Occupational exposure to this PM has been associated with an increase of DNA damage, but there is a scarcity of data examining the impact of these industrial operations in cytogenetic endpoints frequency and cancer risk of potentially exposed surrounding populations. In this study, we used a Geographic Information Systems (GIS) approach and Inverse Distance Weighting (IDW) methods to perform a spatial and statistical analysis to explore whether exposure to PM 2.5 and PM 10 pollution, and additional factors, including the enrichment of the PM with inorganic elements, contribute to cytogenetic damage in residents living in proximity to an open-pit coal mining area. Results showed a spatial relationship between exposure to elevated concentrations of PM 2.5, PM 10 and micronuclei frequency in binucleated (MNBN) and mononucleated (MNMONO) cells. Active pits, disposal, and storage areas could be identified as the possible emission sources of combustion elements. Mining activities were also correlated with increased concentrations of highly enriched elements like S, Cu and Cr in the atmosphere, corroborating its role in the inorganic elements pollution around coal mines. Elements enriched in the PM 2.5 fraction contributed to increasing of MNBN but seems to be more related to increased MNMONO frequencies and DNA damage accumulated in vivo. The combined use of GIS and IDW methods could represent an important tool for monitoring potential cancer risk associated to dynamically distributed variables like the PM., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objective: To explore the difference of cumulative incidence rate of coal workers' pneumoconiosis (CWP) among four large state-owned coal enterprises in northern China, we created an index system for evaluating the quality of comprehensive measures against CWP and applied the system to evaluate and compare the measures of the four coal enterprises., Methods: A two-round Delphi investigation was conducted to identify the indicators in the index system. The weight values of the indicators were calculated with analytic hierarchy process methods. Measures of CWP, mine annals, records and other information in each coal mine of the four enterprises were collected. The evaluation scores, which ranged from 0 to 100, were calculated and compared with., Results: A three-grade index system with 3 first-grade indicators, 9 second-grade indicators and 44 tertiary-grade indicators was established. The expert authority coefficient ( C r ) was 0.75 and the Kendall's coefficient of concordance (Kendall's W ) was 0.15 (χ 2 =193.30, P<0.001). The weight value of 'Geological conditions' was 0.43, equal to 'Dust control engineering technology', and that of 'Occupational health management' was 0.14. The medians and quartiles of the evaluation scores of comprehensive measures against CWP of the four enterprises were 58.38 (54.60~63.02), 64.63 (60.83~67.06), 72.99 (68.92~77.67) and 75.07 (70.73~79.20), respectively., Conclusions: The index system could be effectively used for evaluation and comparison of the comprehensive measures against CWP among different enterprises. The geological conditions and dust control engineering technology played an important role in preventing and controlling CWP., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

In the context of underground coal mining industry, the increased economic issues regarding implementation of additional safety measure systems, along with growing public awareness to ensure high level of workers safety, have put great pressure on the managers towards finding the best solution to ensure safe as well as economically viable alternative selection. Risk-based decision support system plays an important role in finding such solutions amongst candidate alternatives with respect to multiple decision criteria. Therefore, in this paper, a unified risk-based decision-making methodology has been proposed for selecting an appropriate safety measure system in relation to an underground coal mining industry with respect to multiple risk criteria such as financial risk, operating risk, and maintenance risk. The proposed methodology uses interval-valued fuzzy set theory for modelling vagueness and subjectivity in the estimates of fuzzy risk ratings for making appropriate decision. The methodology is based on the aggregative fuzzy risk analysis and multi-criteria decision making. The selection decisions are made within the context of understanding the total integrated risk that is likely to incur while adapting the particular safety system alternative. Effectiveness of the proposed methodology has been validated through a real-time case study. The result in the context of final priority ranking is seemed fairly consistent.

Introduction: Senior managers' attitudes towards safety are very important regarding the safety practices in an organization. The study is to describe the current situation of senior managers' attitudes towards safety in the Chinese coal industry. Method : We evaluated the changing trends as well as the reasons for these changes in the Chinese coal industry in 2009 and in 2014 with 168 senior manager samples from large Chinese state-owned coal enterprises. Evaluations of 15 safety concepts were performed by means of a questionnaire. Results and Conclusions : Results indicate that, in 2014, three concepts were at a very high level (mean > 4.5), and six were at a relatively high level (4.5 > mean > 4.0). Analyses of changing trends revealed that nine concepts improved significantly, while four greatly declined in 2014 compared to those in 2009. The data reported here suggest that the reasons for the significant improvement with respect to the nine concepts include the improvement in social and legal environments, the improvement of the culture of social safety, workers' safety demands being met, and scientific and technical advances in the coal industry. The decline of the four concepts seemed to be caused by a poor awareness of managers in the coal industry that safety creates economic benefits, insufficient information on safety, inadequate attention to the development of a safety culture and safety management methods, and safety organizations and workers' unions not playing their role effectively. Practical Applications : We therefore recommend strengthening the evidence that safety creates economic benefits, providing incentives for employees to encourage their participation in safety management, and paying more attention to the prevention of accidents in coal mines via safety organizations and unions. These results can provide guidelines for workers, industrialists, and government regarding occupational safety in the whole coal industry., Competing Interests: The authors declare no conflict of interest.

This study is a continuation of (Report I) identification of the occupational risk of arterial hypertension (AH) in 13 occupational groups (3842 workers, men). In previous work there was eliminated the influence of traditional factors of the cardiovascular risk, in this study there was implemented the identification of the components of a healthy worker effect (HWE) and the elimination of their influence on the occupational risks of hypertension. Identification and removal of components HWE--the effect of a healthy recruitment (EHR) and the effect of the healthy worker persisting to work (EHWPW--was carried out by the analytic rearranging of the standardized for age and obesity prevalence rate of arterial hypertension with the use of own methodological approaches. For the determination of the presence and severity of EHR there was performed an analysis of the initial prevalence rate of arterial hypertension in the youngest age groups (under 31 years). To overcome HER standardized for age and obesity indices of the arterial hypertension prevalence rate were adjusted by the ratio of the frequency of arterial hypertension in the most young occupational and reference comparable groups. Identification of HWPW was executed by comparing the frequency of AH among workers retiring within 3 years from the occupational groups when compared to the whole sample. Then on the additional risk value there was adjusted the overall prevalence rate of AH in the occupation profession to overcome EHWPW. As a result of the consistent correction and elimination of the influence of HWE components on the prevalence rate of AH, there were obtained risks values, primarily reflecting the impact of occupational factors which can be considered as true occupational risks. Factors of the cardiovascular risk and HWE significantly modified true occupational risks for AH in a number of occupational groups up to inversion. At the same time, the pronouncement of EHR has a paramount importance in the modifying effect.