scholarly journals Study of Top Coal Partition and Key Delayed-Action Region for Horizontal Sublevel Top Coal Caving in Deeply Inclined Seam

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jia-fan Zhang ◽  
Xiaoyu Liu ◽  
Yang Liu ◽  
Xiao-ping Shao ◽  
Hui-mei Zhang
Keyword(s):  
Damage Zone ◽  
Tensile Failure ◽  
Type I ◽  
Coal Seams ◽  
Related Factors ◽  
Factors Affecting ◽  
Working Face ◽  
Sublevel Caving ◽  
Delayed Action ◽  
Arch Structure

Horizontal sublevel caving is the unique way to mine the steep and extra thick coal seams. We aim to determine reasonable height of horizontal subsection, which is crucial to ensure the output and safety of mining. For this aim, a theoretical model is established to determine the theoretical solution of elastic stress distribution in deeply inclined coal seam, and first principal stress expression is derived. And on this basis, related factors affecting the top coal caving property and key delayed-action areas are investigated. The results show that there are four zones in top coal, which are tensile failure zone (TFZ), tensile damage zone (TDZ), elastic zone (EZ), and compression-shear damage zone (CSDZ). The elevation of sublevel height cannot increase the release of top coal. It is necessary to determine the key region of affecting the top coal caving. The key delayed-action region (KDAR) consists of EZ and TFZ in top coal; the EZ and TFZ are type I and II KDAR, respectively, and type I is the key area of weakening top coal. In order to effectively weaken KDAR, opening coal channel of core region, and especially effectively obstructing the continuous moving upward of top coal caving arch structure with the help of weakening top coal body in type I KDAR, would promote caving property of top coal and improve the working face extraction rate.

Pressure Regularity Study of Three Soft Complex Coal Caving Coal Face

2011 ◽  
Vol 217-218 ◽  
pp. 1641-1646
Author(s):  
Nian Jie Ma ◽  
Guo Dong Zhao ◽  
Chun Lei Ju ◽  
Chong Li ◽  
Xiang Zhong Dong
Keyword(s):  
Coal Seam ◽  
Mine Pressure ◽  
Related Factors ◽  
Thick Coal Seam ◽  
Factors Affecting ◽  
Soft Coal ◽  
Working Face ◽  
Distribution Rule ◽  
Mining Coal ◽  
Seam Mining

In order to grasp the movement rules of three soft coal caving complex working plane strata and stoping space surrounding rock and hydraulic support interactions relationship, improve the management of mining roof, to do research about the distribution rule of caused abutment pressure and shield support of initial supporting force, the work resistance and adaptability of coal seam. The first coalface of testing mine 1301 mining coal gangue is clip three soft and thick coal seam mining, adopt fully mechanized caving technology, choose ZF6400/17/32 type support screen type top coal caving hydraulic to support working face roof support, in order to provide better services for safe production in the working face, especially study on related factors affecting the observational of working mine pressure.

scholarly journals Study on the Characteristics of Top-Coal Caving and Optimization of Recovery Ratio in Steeply Inclined Residual High Sectional Coal Pillar

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Wenhua Yang ◽  
Xingping Lai ◽  
Pengfei Shan ◽  
Feng Cui ◽  
Yiran Yang
Keyword(s):  
Bulk Density ◽  
Coal Pillar ◽  
Engineering Practice ◽  
Recovery Ratio ◽  
Coal Seams ◽  
Balance System ◽  
Coal Recovery ◽  
Working Face ◽  
Coal Rock ◽  
Arch Structure

This paper is aimed at solving the technical problems such as low recovery ratio and frequent disasters in steeply inclined and extrathick coal seams at residual high sectional coal pillar. It takes the Wudong Coal Mine as an engineering background, a typical mine of steeply inclined and extrathick coal seams; the structural features of the top-coal caving at the steeply inclined residual high sectional coal pillar were analyzed using methods such as field monitoring and numerical simulation; a mechanical model of the top-coal arch structure was constructed, and the calculation method of top-coal caving height and related influencing factors was obtained. The results showed that the top-coal caving in the steeply inclined residual high sectional coal pillar was characterized as arch. Due to the existence of arch structure, the smooth caving of the top coal was hindered, resulting in a low top-coal recovery ratio, low support pressure at the working face, and differences detected by borehole television on the distribution of the top-coal cracks. With the advancement of the working face, the top-coal arch structure was in the process of dynamic evolution, as the old arch balance system was continuously replaced by the new arch balance system, and it continuously moved towards the upper top coal. The top-coal caving height was affected by factors such as length of the working face, bulk density of overlying coal rock, and cohesion of the top coal. The top-coal caving height increased with the length of the working face and the bulk density of the overlying coal rock mass but was inversely proportional to the cohesion of the top coal. Under the current mining conditions, the top-coal caving height was 39.8 m, which was much lower than the residual high sectional coal pillar height (71 m); the top coal cannot collapse completely. Based on the characteristics of the top-coal caving structure, the technology of sublevel advanced presplitting blasting was adopted to weaken the top coal in engineering practice, so that the top-coal caving structure moved up naturally. The daily coal production in the working face has increased by an average of 2419.6 tons, which has significantly improved the top-coal recovery ratio and production efficiency. The result provided a theoretical basis and application reference for similar residual high sectional coal pillar recovery.

scholarly journals Movement and Protection for Random Shape Rockfalls in Steeply Dipping Coal Seams

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Ming Liu ◽  
Jie Chen
Keyword(s):  
3D Model ◽  
Peak Stress ◽  
Time Interval ◽  
Random Shape ◽  
Coal Seams ◽  
Factors Affecting ◽  
Grid Model ◽  
Working Face ◽  
System Data ◽  
Geographic Information System Data

In view of the randomness of rockfalls shape and irregularity of the bottom floor of working face in steeply dipping coal seams (SDCS), it is difficult to accurately simulate rockfall movement, and it is consequently unable to effectively protect against multirockfalls. Therefore, a method for generating random shape rockfalls based on ellipsoid equation is proposed, and a 3D grid model of real bottom floor of working face is established based on the geographic information system data. In order to verify the accuracy and feasibility of the method and 3D model, the trajectory simulated by Rockyfor3D software is compared, and the proposed method and 3D model prove to be effective in simulating rockfall movement more accurately. Then the proposed method and 3D grid model are applied to solve the problem of multirockfalls protection in numerical simulation, and the main factors affecting the structural stress response of protective netting are analyzed by taking three incident modes of parallel heights, ladder parallel, and the same trajectory. In the simulation, it is found out that the trajectory of irregular rockfalls is greatly affected by the shape of rockfall and working face floor; during the process of multiple rockfalls colliding with the protective netting, the peak stress on the protective netting is inversely proportional to both the time interval between each rockfall and the distance between each rockfall. The findings presented in this research contribute to rockfall prediction and protection against rockfall hazards.

Consumer Online Buying Decisions: A Critical Appraisal of Literature

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Amit Kishore Sinha ◽  
Gyanendra B. S. Johri ◽  
Shanti Rai
Keyword(s):  
Research Paper ◽  
Business Environment ◽  
Buying Behavior ◽  
Related Factors ◽  
Factors Affecting ◽  
Goods And Services ◽  
Online Stores ◽  
Online Buying ◽  
Indian Cities ◽  
Buying Decisions

Since last two decades buying of goods and services from online stores using Internet started off. But players of this industry could reach to the general public residing in second and third category Indian cities in recent past only. Now companies are eagerly interested in understanding the factors affecting Indian consumers so that their needs and wants can be understood and served profitably. This research paper is an attempt to critically evaluate those factors which affect consumer buying behavior in Indian Internet based business environment. For the purpose of coverage of topic researcher has classified the literature under three categories which are Literature related to vendor related factors, Literature related to consumer related factors and Literature related to other factors. Vendor related factors include those factors which are primarily controlled by the companies that are engaged in selling their goods and services on internet along with their intermediaries through which such sales take place. Consumer related factors have been bifurcated under two heading that are consumer demographic factors and consumer psychographic factors. Besides this there are several other factors which may affect consumer’s buying decisions and they are classified as other factors. This research paper also tries to identify the gaps (if any) in the available literature of the factors affecting consumer online buying decisions.

scholarly journals Investigating the status of marital burnout and related factors in married women referred to health centers

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mahbobeh Nejatian ◽  
Ali Alami ◽  
Vahideh Momeniyan ◽  
Ali Delshad Noghabi ◽  
Alireza Jafari
Keyword(s):  
Marital Satisfaction ◽  
Significant Relationship ◽  
Married Couples ◽  
Married Women ◽  
Health Centers ◽  
Related Factors ◽  
Factors Affecting ◽  
The Status ◽  
Multistage Sampling ◽  
Emotional Burnout

Abstract Background Marital burnout is an important issue in marriage and many factors play an important role in this phenomenon. The aim of this study was to determine the status of marital burnout and the factors affecting married women who were referred to health centers because of it. Methods In this study, 936 women were selected by multistage sampling and data collection was performed using questionnaires of demographic and couple burnout. Data analysis was performed using SPSS software version 24. Results The mean (± SD) of marital burnout, in this study, was 55.46 (± 18.03) (out of 147 score). There was a significant relationship between the level of women's education with total marital burnout, and the subscales of somatic and emotional burnout (P < 0.05). A significant relationship was also observed between mandatory marriage and total marital burnout, as well as subscales of somatic, emotional, and psychological burnout (P < 0.05). A significant relationship was detected and observed between women's participation in training courses of communication skills and total marital burnout, inclusive of the subscales regarding psychological burnout (P < 0.05). The results of linear regression showed a significant relationship between mandatory in marriage, marital satisfaction, marriage duration, and husband's level of education with women's marital burnout. The variables were finally able to predict 12% of marital burnout variance. It should be noted that marital satisfaction had a higher effect on predicting marital burnout (P < 0.001). Conclusions Marital satisfaction was one of the effective factors in predicting marital burnout, so it can be concluded that it is necessary to pay more attention to this issue. Educational programs and examining the factors that enhance marital satisfaction are needed to prevent and reduce marital burnout in married couples.

scholarly journals Comprehensive technical support for safe mining in ultra-close coal seams: A case study

2021 ◽  
pp. 014459872110093
Author(s):  
Wei Zhang ◽  
Jiawei Guo ◽  
Kaidi Xie ◽  
Jinming Wang ◽  
Liang Chen ◽  
...  
Keyword(s):  
Coal Seam ◽  
Technical Support ◽  
Surrounding Rock ◽  
Coal Seams ◽  
Deformation Control ◽  
Hard Roof ◽  
Working Face ◽  
Close Coal Seams ◽  
Safe Mining

In order to mine the coal seam under super-thick hard roof, improve the utilization rate of resources and prolong the remaining service life of the mine, a case study of the Gaozhuang Coal Mine in the Zaozhuang Mining Area has been performed in this paper. Based on the specific mining geological conditions of ultra-close coal seams (#3up and #3low coal seams), their joint systematic analysis has been performed, with the focus made in the following three aspects: (i) prevention of rock burst under super-thick hard roof, (ii) deformation control of surrounding rock of roadways in the lower coal seam, and (iii) fire prevention in the goaf of working face. Given the strong bursting tendency observed in upper coal seam and lower coal seam, the technology of preventing rock burst under super-thick hard roof was proposed, which involved setting of narrow section coal pillars to protect roadways and interleaving layout of working faces. The specific supporting scheme of surrounding rock of roadways in the #3low1101 working face was determined, and the grouting reinforcement method of local fractured zones through Marithan was further proposed, to ensure the deformation control of surrounding rock of roadways in lower coal seams. The proposed fire prevention technology envisaged goaf grouting and spraying to plug leaks, which reduced the hazard of spontaneous combustion of residual coals in mined ultra-close coal seams. The technical and economic improvements with a direct economic benefit of 5.55 million yuan were achieved by the application of the proposed comprehensive technical support. The research results obtained provide a theoretical guidance and technical support of safe mining strategies of close coal seams in other mining areas.

scholarly journals What Affects Chinese Residents’ Perceptions of Climate Change?

2018 ◽  
Vol 10 (12) ◽  
pp. 4712 ◽  
Author(s):  
Jinjia Wu ◽  
Jiansheng Qu ◽  
Hengji Li ◽  
Li Xu ◽  
Hongfen Zhang ◽  
...  
Keyword(s):  
Climate Change ◽  
Public Awareness ◽  
Public Understanding ◽  
Related Factors ◽  
Climate Change Risk ◽  
Climate Governance ◽  
Factors Affecting ◽  
National Education ◽  
The Public ◽  
Mitigation And Adaptation

The theme of global sustainable development has changed from environmental management to climate governance, and relevant policies on climate governance urgently need to be implemented by the public. The public understanding of climate change has become the prerequisite and basis for implementing various climate change policies. In order to explore the affected factors of climate change perception among Chinese residents, this study was conducted across 31 provinces and regions of China through field household surveys and interviews. Combined with the residents’ perception of climate change with the possible affected factors, the related factors affecting Chinese residents’ perception of climate change were explored. The results show that the perceptive level of climate change of Chinese residents is related to the education level and the household size of residents. Improving public awareness of climate change risk in the context of climate change through multiple channels will also help to improve residents’ awareness of climate change. On the premise of improving the level of national education, improving education on climate change in school education and raising awareness of climate change risk among dependents will help to improve the level of Chinese residents’ awareness of climate change, which could be instrumental in promoting public participation in climate change mitigation and adaptation actions.

Unfilled Training Positions in Germany – Regional and Establishment-Specific Determinants

2019 ◽  
Vol 239 (4) ◽  
pp. 661-701 ◽  
Author(s):  
Sandra Dummert ◽  
Ute Leber ◽  
Barbara Schwengler
Keyword(s):  
Related Factors ◽  
Factors Affecting ◽  
External Conditions ◽  
Western Germany ◽  
Enterprise Level ◽  
Specific Factors ◽  
Regional Factors ◽  
The One ◽  
Training Position ◽  
Quantitative Importance

AbstractThe current situation in the German apprenticeship market is characterized by two contradictory developments. On the one hand, establishments are experiencing increasing problems filling the training positions they offer, and the number of vacant training positions is climbing. On the other hand, the transition into training is still difficult for many young people, and the number of unsuccessful vocational training applicants is rising. Hence, matching supply with demand is becoming increasingly difficult in the German job market for training positions. Using the Linked Employer-Employee dataset (LIAB) from the Institute for Employment Research (IAB), our paper provides a closer examination of the phenomenon of unfilled training positions. It presents an overview of the evolution of vacant training positions in eastern and western Germany and attempts to explain the number of vacancies by investigating the factors responsible for the establishments’ inability to fill their training positions. We assume that training position vacancies are due not only to internal company reasons such as firm size or the wage offer for apprentices but also to external conditions such as general regional factors. Therefore, our analysis also considers the situation on the demand side of the labor market within a region. The results of our multilevel mixed-effects estimations show that in addition to characteristics on the enterprise level, regional determinants also affect the share of vacant apprenticeships. With respect to establishment-related factors, mainly characteristics that describe the attractiveness of the firm prove to be important. With regard to regional-specific factors, we find that the availability of school leavers in a region in addition to the level of regional-sectoral competition impacts the recruiting success of establishments. Our analysis also shows that there are remarkable differences between eastern and western Germany concerning both the quantitative importance of unfilled training positions and the factors affecting them.

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