Permeability Characteristics and Classification of Coal Seams in Nigeria

2009 ◽  
Vol 62-64 ◽  
pp. 357-367
Author(s):  
B.M. Olaleye ◽  
O.O. Onyemaobi ◽  
J.M. Akande
Keyword(s):  
Coal Seam ◽  
Triaxial Compression ◽  
Pressure Gauge ◽  
Water Tank ◽  
Permeability Test ◽  
Coal Seams ◽  
Permeability Characteristics ◽  
Water Infusion ◽  
The Difference

In this work, the permeability characteristics of Nigerian coal seams were determined and these properties were used to investigation the applicability of water infusion in the coal seams to solve coal-mining problems. The experimental work was conducted with Triaxial Compression Machine adapted for the permeability test comprising of Hoek cell, a self- developed water piston, pressure gauge and an overhead water tank. The results of the investigation showed that the permeability measurements of the coals were consistent at the different sites and locations of the coalmines. It also revealed that the difference in coal seam permeability was relatively small in Nigeria.

scholarly journals Pore distribution and classification of loess

2021 ◽  
Vol 261 ◽  
pp. 03002
Author(s):  
Qianqian Liu ◽  
Tiehang Wang
Keyword(s):  
Permeability Coefficient ◽  
Pore Diameter ◽  
Soil Samples ◽  
Permeability Test ◽  
Pore Characteristics ◽  
Permeability Characteristics ◽  
Profound Influence ◽  
Porosity Ratio ◽  
Scanning Electron

The micro-pore characteristics in undisturbed loess have a profound influence on the permeability characteristics. Based on the results of permeability test, it is proved that the permeability coefficient of soil samples with the same porosity ratio is different and the internal characteristics are diversified. The internal pores of undisturbed loess were studied by scanning electron microscopy (SEM). The results show that there are obvious differences in the internal microstructure of the original loess with the same porosity ratio. There are root holes in undisturbed loess, the number and size of which directly affect the value of permeability coefficient. With the increase of pore diameter, the pore size distribution changes gradually, and the influence of small pores is gradually weakened, while the influence of large pores is more obvious. Therefore, only the pore ratio parameter used in engineering can not completely describe the pore characteristics of soil, it is necessary to introduce other microscopic parameters to describe.

Depression, pain, and site:

1999 ◽  
Vol 15 (1) ◽  
pp. 10-17
Author(s):  
Molina Omar Franklin ◽  
Tavares Gimenes Pablo ◽  
Aquilino Raphael ◽  
Rank Rise ◽  
Coelho Santos Zeila ◽  
...  
Keyword(s):  
Visual Analogue Scale ◽  
Beck Depression Inventory ◽  
Temporomandibular Disorders ◽  
Analogue Scale ◽  
Epidemiological Data ◽  
Depression Severity ◽  
Internal Joint ◽  
The Difference ◽  
Biomechanical Tests

Objective: To assess the level of depression, severity of pain and pain in single/multiple sites in patients with different severity of bruxing behavior and Temporomandibular Disorders (TMDs). Methods: We evaluated 131 patients with bruxism and TMDs: 20 patients with mild bruxism, 42 patients with moderate bruxism, 45 patients with severe bruxism and 24 patients with extreme bruxism. We used the Beck Depression Inventory (BDI), clinical examination, a questionnaire of clinical epidemiological data, criteria for TMDs and bruxism, palpation of muscles and joints, the Visual Analogue Scale for pain, classification of the occlusion and biomechanical tests to assess for internal joint derangements. Results: The level of depression increased from the mild, to the moderate, severe and extreme bruxing behavior groups, but the difference was significant only from the mild to the extreme group (p<0.001). Pain levels increased from the mild and moderate to the severe and extreme subgroups, but were not statistically significant. Mean number of pain sites increased from the mild, to the moderate, severe and extreme subgroup and the difference was extremely significant (p<0.0001). Conclusion: Levels of depression, severity of pain and pain sites increased with severity of bruxing behavior. A higher number of pain sites with more severe bruxism indicates somatization in bruxers, but a further study using the same protocol and a psychological test for somatization would be indicated to further substantiate these findings.

scholarly journals Cooperative Control Mechanism of Long Flexible Bolts and Blasting Pressure Relief in Hard Roof Roadways of Extra-Thick Coal Seams: A Case Study

2021 ◽  
Vol 11 (9) ◽  
pp. 4125
Author(s):  
Zhe Xiang ◽  
Nong Zhang ◽  
Zhengzheng Xie ◽  
Feng Guo ◽  
Chenghao Zhang
Keyword(s):  
Coal Seam ◽  
Cooperative Control ◽  
Field Tests ◽  
Surrounding Rock ◽  
Deep Hole ◽  
Coal Seams ◽  
Thick Coal Seam ◽  
Structure Damage ◽  
Hard Roof

The higher strength of a hard roof leads to higher coal pressure during coal mining, especially under extra-thick coal seam conditions. This study addresses the hard roof control problem for extra-thick coal seams using the air return roadway 4106 (AR 4106) of the Wenjiapo Coal Mine as a case study. A new surrounding rock control strategy is proposed, which mainly includes 44 m deep-hole pre-splitting blasting for stress releasing and flexible 4-m-long bolt for roof supporting. Based on the new support scheme, field tests were performed. The results show that roadway support failure in traditional scenarios is caused by insufficient bolt length and extensive rotary subsidence of the long cantilever beam of the hard roof. In the new proposed scheme, flexible 4-m-long bolts are shown to effectively restrain the initial expansion deformation of the top coal. The deflection of the rock beam anchored by the roof foundation are improved. Deep-hole pre-splitting blasting effectively reduces the cantilever distance of the “block B” of the voussoir beam structure. The stress environment of the roadway surrounding rock is optimized and anchorage structure damage is inhibited. The results provide insights regarding the safe control of roadway roofs under extra-thick coal seam conditions.

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 Classification of coal seam outburst hazards and evaluation of the importance of influencing factors

2017 ◽  
Vol 9 (1) ◽  
Author(s):  
Xianzhi Shi ◽  
Dazhao Song ◽  
Ziwei Qian
Keyword(s):  
Coal Seam ◽  
Multivariate Regression ◽  
Multivariate Regression Analysis ◽  
Scientific Basis ◽  
Prevention Measures ◽  
Coal Seam Gas ◽  
Geological Factors ◽  
Hazard Level ◽  
Outburst Hazard

AbstractCoal and gas outbursts are the result of several geological factors related to coal seam gas (coal seam gas pressureTo classify the outburst hazard level of a coal seam by means of statistical methods, this study considered the geological parameters of coal seam gas and statistical data on the amount of material involved in coal outbursts. Through multivariate regression analysis, a multivariate regression equation between the outburst coal quantity andUsing a significance evaluation of the aforementioned factors, the relative contributions of the gas-related geological parameters to the outburst hazard level of a coal seam were found to follow the orderThis work provides a scientific basis for evaluating the outburst hazard level of a coal seam and adopting feasible and economical outburst-prevention measures.

scholarly journals Events, Time and the Simple Form

2009 ◽  
Vol 17 (1) ◽  
pp. 85-105 ◽  
Author(s):  
Walter H. Hirtle
Keyword(s):  
Simple Form ◽  
Point Of View ◽  
Event Time ◽  
The Difference ◽  
Time Required ◽  
English Verb

Abstract This is an attempt to discern more clearly the underlying or POTENTIAL meaning of the simple form of the English verb, described in Hirtle 1967 as 'perfective'. Vendler's widely accepted classification of events into ACCOMPLISHMENTS, ACHIEVEMENTS, ACTIVITIES, and STATES is examined from the point of view of the time necessarily contained between the beginning and end of any event, i.e. EVENT TIME as represented by the simple form. This examination justifies the well known dynamic/stative dichotomy by showing that event time is evoked in two different ways, that, in fact, the simple form has two ACTUAL significates. Further reflection on the difference between the two types thus expressed—developmental or action-like events and non-developmental or state-like events—leads to the conclusion that the simple form provides a representation of the time required to situate all the impressions involved in the notional or lexical import of the verb.

Russia and EU Countries: Partnership for Modernization

2013 ◽  
pp. 54-61
Author(s):  
T. Romanova ◽  
E. Pavlova
Keyword(s):  
Rule Of Law ◽  
New Classification ◽  
Member States ◽  
The Rule Of Law ◽  
Normative Power ◽  
Eu Member States ◽  
The World ◽  
The Difference ◽  
The Eu

The article examines how the normative power, which the EU puts forward as an ideological basis of its actions in the world, manifests itself in the national partnerships for modernization between Russia and EU member states. The authors demonstrate the influence of the EU’s normativity on its approach to modernization as well as the difference in the positions of its member countries. It is concluded that there is no unity in the EU’s approach to democracy, human rights and the rule of law, and the new classification of EU member states, which is based on their readiness to act in accordance with the Union’s concept of normative power, is offered.

BOREHOLE‐RADAR EXPLORATION IN A COAL SEAM

Geophysics ◽  
1977 ◽  
Vol 42 (6) ◽  
pp. 1254-1257 ◽  
Author(s):  
John C. Cook
Keyword(s):  
Coal Seam ◽  
Practical Importance ◽  
Low Resolution ◽  
Coal Seams ◽  
Australian Society ◽  
Great Practical Importance ◽  
The Third ◽  
Research Organizations ◽  
Borehole Radar ◽  
Experimental Use

The experimental use of “geologic radar” to explore through coal from mined passages underground has already been reported elsewhere (Cook, 1973, 1974). Low‐resolution borehole radar work in salt, a much more favorable medium, has also been reported (Holzer et al., 1972). The purpose of this paper is to report the first known results of borehole radar tests in coal. The exploration of coal seams via boreholes from the surface is potentially a technique of great practical importance. The borehole experiment was performed in conjunction with a month‐long program of radar tests in Australian collieries and quarries performed under the sponsorship of the third ICOGEO and supported by several Australian mining and research organizations. A report on that program is expected to appear in the Bulletin of the Australian Society of Exploration Geophysicists some time during 1977.

scholarly journals Slovene-English Contrastive Phraseology: Lexical Collocations

2010 ◽  
Vol 7 (2) ◽  
pp. 57-73
Author(s):  
Primož Jurko
Keyword(s):  
English Language ◽  
Focal Point ◽  
Systematic Classification ◽  
Lexical Collocations ◽  
The Difference ◽  
Translation Errors ◽  
Language Pair

Phraseology is seen as one of the key elements and arguably the most productive part of any language. %e paper is focused on collocations and separates them from other phraseological units, such as idioms or compounds. Highlighting the difference between a monolingual and a bilingual (i.e. contrastive) approach to collocation, the article presents two distinct classes of collocations: grammatical and lexical. %e latter, treated contrastively, represent the focal point of the paper, since they are an unending source of translation errors to both students of translation and professional translators. %e author introduces a methodology of systematic classification of lexical collocations applied on the Slovene-English language pair and based on structural (lexical congruence) and semantic (translational predictability) criteria.

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