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Research Article
Research and Application of Different Coal Wall Spalling Forms
Yajun Xu*,
Yibo Du,
Kun Zhang,
Xiaoliang Pang,
Yongxiang Xu
Issue:
Volume 12, Issue 6, December 2023
Pages:
188-197
Received:
21 September 2023
Accepted:
23 October 2023
Published:
9 November 2023
Abstract: Coal wall spalling is a key technical problem for surrounding rock control in fully mechanized mining face. For many years, coal wall spalling has mainly been studied through laboratory experiments based on coal samples, and in recent years, numerical simulation software has been used for simulation analysis. Theoretical research is mainly based on a two-dimensional coal wall model. At present, the academic circle divides the coal wall spalling into two forms: shear and tensile spalling. However, the mechanism of coal wall spalling was not clear, and it is difficult to describe the causes of different spalling forms in different coal seam conditions. To solve the above problems, according to the characteristics of coal wall spalling, a three-dimensional simplified model of rib spalling is derived based on the plane spline stress balance condition. Based on this, fully considering the influence of overburden pressure, coal rock interface cohesion, and internal friction angle on shear stress and internal shear stress of coal, the stress balance equation of the coal wall spalling body based on a three-dimensional wedge model is established, and the calculation formula of coal wall slope fracture angle is derived combined with the shear failure characteristics of soft coal and tensile failure characteristics of hard coal. The formula of coal wall fracture angle integrates parameters such as coal seam depth, dynamic pressure coefficient, coal rock interface cohesion and internal friction angle, Poisson's ratio, coal cohesion, and internal friction angle. The shear failure of soft coal and the tensile failure of hard coal are characterized by a unified formula. The effects of coal seam depth, coal rock interface cohesion and internal friction angle, coal cohesion and internal friction angle, Poisson's ratio, and other parameters on coal wall fracture angle are studied. The mechanism of soft coal seam, medium hard coal seam, and hard coal seam rib spalling is analyzed, and the characteristics of shear sliding failure of soft coal seam, block failure of medium hard coal seam and plate slope of hard coal seam are well explained. Taking the fully mechanized face with large mining height in the hard coal seam of Jinjitan coal mine as an example, the fracture angle of the coal seam is calculated, and the characteristics of coal wall spalling like plate shape are well explained, which provides a practical theoretical analysis method for the final solution of this problem.
Abstract: Coal wall spalling is a key technical problem for surrounding rock control in fully mechanized mining face. For many years, coal wall spalling has mainly been studied through laboratory experiments based on coal samples, and in recent years, numerical simulation software has been used for simulation analysis. Theoretical research is mainly based on...
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Research Article
Treatment of Permanganate Oxidation and Bioremediation on Petroleum Hydrocarbons Contaminated Soil and the Effect on Soil Function
Issue:
Volume 12, Issue 6, December 2023
Pages:
198-205
Received:
19 October 2023
Accepted:
6 November 2023
Published:
13 November 2023
Abstract: The impact of potassium permanganate oxidation-bioremediation on soil function can be divided into three stages: the oxidation stage, the transition stage, and the bioremediation stage. In order to obtain a deeper revelation of the effect on soil function, the nitrogen, phosphorus, organic matter (OM), dissolved organic carbon (DOC) and petroleum hydrocarbons (TPH) during these three phases of remediation have been investigated. Potassium permanganate (PP) was consumed after 24 hours’ reaction. During this phase, a larger removal rate of TPH was achieved at a PP molar concentration of 0.05 and 0.1 mol/L and under weak acidic or basic conditions. 18%-61% of TPH was removed in 24 hours. PP has a strong impact on soil functionality. Addition of oxidation agent largely decreased DOC amount in soil. However, DOC and the proportion of active OM in soil increased as the connection time (phase two) was prolonged. DOC amount was 172% increased after 60d. After the three phases’ combined remediation, more than 70% of the TPH in soil was reduced while the maximum removal rate was 97.35%. The concentration of the C10-C12 segment has significantly diminished to the point of near disappearance, while the C19-C40 segments have experienced an approximate 40% reduction. The removal rate for high-carbon chain segments remains satisfactory. Addition of tween-80 effectively increased the solubilization and removal rate of TPH while introduced DOC into the reaction system. Moreover, the previous consumption of oxidizers is relatively slow, making it an ideal additive for high organic pollutant-low soil organic matter affinity. Results showed that adjustment of pH and oxidation agent amount, increase of connection time between oxidation and bioremediation, introduction of appropriate additive were capable of reducing the negative impact on soil by remediation.
Abstract: The impact of potassium permanganate oxidation-bioremediation on soil function can be divided into three stages: the oxidation stage, the transition stage, and the bioremediation stage. In order to obtain a deeper revelation of the effect on soil function, the nitrogen, phosphorus, organic matter (OM), dissolved organic carbon (DOC) and petroleum h...
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Research Article
Study on the Influence of Different Surface Vegetation Cover on Watershed Scale Microclimate Change
Wang Fu,
Zhao Qiang,
Sha Xiao Yan,
He Qian,
Zhang He,
Han Fen
Issue:
Volume 12, Issue 6, December 2023
Pages:
206-224
Received:
20 October 2023
Accepted:
6 November 2023
Published:
13 November 2023
Abstract: By comparing and observing the changes of microclimate indicators of different types of vegetation cover in the Hulu River Basin, this paper analyzed the changes of microclimate under different underlying surface conditions caused by vegetation cover and discussed the role and influence of fruit tree economic forest cover on watershed scale microclimate change. The results showed that the cover of fruit tree economic forest had the effects of cooling, temperature accumulation, moistening and reducing wind speed on the underlying surface of the basin to a certain extent, which was conducive to improving the microclimate of small watershed. The average daily temperature in the forest decreased by 0.1 ~ 3.0°C compared with the average air temperature in the open land outside the forest, and the regulating effect of fruit tree economic forest was higher than that of water conservation forest. The cumulative temperature effect made the daily maximum temperature in the forest higher than that in the open area outside the forest by 0.4 ~ 1.1°C. The humidification and moisturizing effect made the relative humidity of air in the forest increase by 3.2% ~ 11.1% compared with that outside the forest, and the average daily wind speed of air in the forest was 0.4m/s ~ 4.0m/s lower than that outside the forest.
Abstract: By comparing and observing the changes of microclimate indicators of different types of vegetation cover in the Hulu River Basin, this paper analyzed the changes of microclimate under different underlying surface conditions caused by vegetation cover and discussed the role and influence of fruit tree economic forest cover on watershed scale microcl...
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Research Article
Genesis and Classification of Soils on a Toposequence in Guelendeng, Southwest Chad
Agoubli Issiné*,
Touroumngaye Goalbaye,
Ahmat Amine Cherif,
Hara Toukou
Issue:
Volume 12, Issue 6, December 2023
Pages:
225-232
Received:
17 October 2023
Accepted:
10 November 2023
Published:
29 November 2023
Abstract: A study was carried out in Guelendeng in the south west of Chad with the objective to determine the main process at the origin of soil formation and to classify the soils along a toposequence. Three pedological profiles have been dug with variable depths. The three soil profiles namely G1, G2 and G3 were dug respectively, in the upslope, midslope and the footslope; samples were collected from each horizon in each of the three profiles. The collected samples were labelled and sent to laboratories for mineralogical, geochemical and physicochemical analyses. The mineralogical analysis of the collected samples allowed to highlight the dominance of primary minerals, namely quartz and feldspar. The geochemical analysis of the samples collected in the different profiles shows that SiO2 is by far the most abundant oxide. The physicochemical analysis shows very high sand contents ranging from 72.5 to 88.00% in profile G1; from 73.5 to 76.5% in profile G2 and from 75.0 to 79.5% in profile G3. In each profile, sand contents increase with depth. The pH-water varies from 5.1 to 6.5 in profile G1; in profile G2, it varies from 5.5 to 6.6; it is from 5.4 to 5.9 in profile G3. The pH values are highest in the surface horizons and decrease with increasing depth. For each sample, the change in pH (ΔpH) is negative. The sums of exchangeable bases are low as are the exchangeable cations. The cation exchange capacities are also low as shown by the values of the exchangeable cation sums. The other nutrients, namely calcium, magnesium, organic carbon, nitrogen, available phosphorus, potassium, sodium and organic matter are also very poorly represented and the C/N values are also very low. According to the WRB, all three soils in the site are Arenosols. The colors of the different pits induce some nuances in the designations. According to the CPCS, they are sols ferrugineux tropicaux peu ou non lessivés. The dominant process of pedogenesis is monosiallitisation. The bad drainage due to relatively less abundant rainfall is the factor responsible for the presence of 2/1 minerals like smectite.
Abstract: A study was carried out in Guelendeng in the south west of Chad with the objective to determine the main process at the origin of soil formation and to classify the soils along a toposequence. Three pedological profiles have been dug with variable depths. The three soil profiles namely G1, G2 and G3 were dug respectively, in the upslope, midslope a...
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Research Article
Electrical Resistivity Imaging for Characterizing the Shallow Landslide Hazard Site at Kutupalong Rohingya Refugee Camps of Ukhiya, Cox's Bazar, Bangladesh
Abu Taher Mohammad Shakhawat Hossain,
Mohammad Hasan Imam*,
Hossain Mohammad Sayem,
Purba Anindita Khan,
Mohammad Emdadul Haque,
Mahmuda Khatun,
Sheikh Jafia Jafrin,
Tonmoy Dutta,
Hasan Mahmud
Issue:
Volume 12, Issue 6, December 2023
Pages:
233-243
Received:
30 October 2023
Accepted:
16 November 2023
Published:
29 November 2023
Abstract: Electrical imaging survey technique is especially suitable for shallow site investigations where understanding the complexities of the subsurface structure in detail is important. This study has been carried out to identify subsurface lithological variation by showing a connection between resistivity data and basic geotechnical parameters. The Wenner arrangement of approximately 25 m and 50 m image lines with electrode spacing of 1 m and 2 m respectively have been carried out to collect the resistivity data. The changes of shallow subsurface geo-electric layers are unfolded using RES2DINV software by creating the electrical images for a site located in the Kutupalong Rohingya Refugee Camps area in Ukhiya-Teknaf, Cox's Bazar, Bangladesh. Fundamental geotechnical parameters of the soils of the Kutupalong Site including moisture content, particle size distribution, liquid limit, plastic limit, plasticity index, and specific gravity values were evaluated. The importance of the electrical resistivity values was validated by comparing these geotechnical characteristics with the generated electrical images. As a result, the apparent resistivity pseudo sections give a very approximate but nevertheless useful picture that is illustrated on the image lines revealing subsurface geological changes and support to improve shallow landslide site characterization, in addition to the existing geotechnical site characterization method.
Abstract: Electrical imaging survey technique is especially suitable for shallow site investigations where understanding the complexities of the subsurface structure in detail is important. This study has been carried out to identify subsurface lithological variation by showing a connection between resistivity data and basic geotechnical parameters. The Wenn...
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Research Article
Mangrove Interspecies Classification Based on UAV Hyperspectral Images
Lina Yi,
Guifeng Zhang*,
Feiyang Lu,
Yongcha Zhou
Issue:
Volume 12, Issue 6, December 2023
Pages:
244-248
Received:
7 November 2023
Accepted:
9 December 2023
Published:
14 December 2023
Abstract: In recent years, the UAV light-weighted hyperspectral imaging system has become more available. It can provide high spatial and spectral resolution images for environment monitoring. Mangrove forest interspecies distribution map is important data source for the government to design the protection policy. A research on UAV hyperspectral remote sensing surveying of mangrove forest is implemented in Futian Nature Reserve area located In Shenzhen, China. The UAV-based hyperspectral images were collected and processed to get the geometrically corrected mosaicked reflectance data that was latter used to extract the mangrove interspecies map. Based on the hyperspectral data, the supervised pixel-based classification methods were implemented. Firstly, NDVI is used to distinguish mangrove forest from other ground object features based on the decision tree classification method with expert knowledge. Then MNF transformation is performed on the hyperspectral data to get the transformed feature that represents the most information of the hyperspectral bands. Next, the best exponential factor formula (OIF) method is used to analyze the first 10 band features chosen by the MNF transformation to get the optimal band combination for classification. Finally, the pixel-based maximum likelihood, minimum distance classification methods are used to classify the mangrove interspecies. The classification results show the distribution of mangrove areas. The pixel-based minimum distance method performs better and the overall classification accuracy can reach to 98.21%.
Abstract: In recent years, the UAV light-weighted hyperspectral imaging system has become more available. It can provide high spatial and spectral resolution images for environment monitoring. Mangrove forest interspecies distribution map is important data source for the government to design the protection policy. A research on UAV hyperspectral remote sensi...
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