Secondary Gob-side Entry Retaining Technology with Double Side Roof Cutting and Pressure Relief in Thin Coal Seam
Luying Shao,
Bingxiang Huang,
Xinglong Zhao
Issue:
Volume 8, Issue 5, September 2020
Pages:
91-102
Received:
31 August 2020
Accepted:
14 September 2020
Published:
23 September 2020
Abstract: In order to solve the problems of stress concentration and large deformation of surrounding rock of secondary gob-side entry retaining in thin coal seam caused by hard overhanging roof, the method of cutting off overhanging roof on both sides of roadway by manual pre-cutting seam is adopted. It can transfer high stress to goaf on both sides of roadway and reduce roadway deformation. The mechanism of roadway formation, the conditions of double side overhanging roof subsidence and the stress reduction of roadway side support of secondary gob-side entry retaining after double side roof cutting are given. This paper studies the pressure relief law of secondary gob side entry retaining after double side roof cutting in thin coal seam. After double side roof cutting, the stress of roadway side support is reduced by 76%, the maximum vertical displacement of roof is reduced by 84%, and high stress is transferred to goaf. The influence of different double side roof cutting thickness and angle on the pressure relief effect is analyzed. On the premise that the collapsed gangue can fill the goaf, the smaller the thickness of double side roof cutting is, the better the pressure relief effect is, and the greater the double side roof cutting angle is, the better the pressure relief effect is. It has been successfully applied in the left five roadway of No. 69 coal seam in Xinqiang coal mine, and the deformation of roof and floor is reduced by 47% and the deformation of two sides is reduced by 56% after double side roof cutting. It has important reference value for the future secondary gob-side entry retaining.
Abstract: In order to solve the problems of stress concentration and large deformation of surrounding rock of secondary gob-side entry retaining in thin coal seam caused by hard overhanging roof, the method of cutting off overhanging roof on both sides of roadway by manual pre-cutting seam is adopted. It can transfer high stress to goaf on both sides of road...
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Experiment Study on Coal Roadways Roof Monitoring Based on the Pre-stretched Optical Fiber Lay out at Fixed-points
Tao Hu,
Su Bu,
GY Hou,
Yan Wang,
Ziyi Hu,
Zixiang Li,
Jinping Liang,
Yuliang Zhou,
Haoyong Jing
Issue:
Volume 8, Issue 5, September 2020
Pages:
103-115
Received:
24 September 2020
Accepted:
30 September 2020
Published:
7 October 2020
Abstract: The safety monitoring of coal roadways roof is the key to prevent roof accidents and ensure coal mines safety. However, the monitoring blind zones caused by traditional methods is one of the main reasons of frequent roof accidents. To ensure the safety of coal mines production, a novel roof monitoring method is proposed in this paper, which is based on the distributed optical fiber sensing (DOFS) and the pre-stretched optical fiber layout at fixed points (POFLF). The research of this approach has been carried out through analysis of DOFS optical fiber strain monitoring and POFLF theory, and with the help of indoor optical fiber strain experiment. Finally the approach was applied in the field monitoring of a coal roadway roof. Aforementioned verified the optical fiber strain distribution not only accurately indicate the roof settlement range, but also qualitatively and quantitatively demonstrate the roof subsidence displacement. The feasibility and validation of the approach as a supplementary or auxiliary resorts in roof safety monitoring were confirmed. The research in this paper not only has important reference significance for the safety monitoring of coal roadways roof under similar geological and production conditions, but be of helpful for improving the coal mine safety as well.
Abstract: The safety monitoring of coal roadways roof is the key to prevent roof accidents and ensure coal mines safety. However, the monitoring blind zones caused by traditional methods is one of the main reasons of frequent roof accidents. To ensure the safety of coal mines production, a novel roof monitoring method is proposed in this paper, which is base...
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Economic Evaluation of Beneficiating Nigerian Bentonite Using Periwinkle Shell and Mucuna Solannie
Kevin Chinwuba Igwilo,
Anthony Kerunwa,
Bala S. Zakka,
Izunna Chinemelum Okeke
Issue:
Volume 8, Issue 5, September 2020
Pages:
116-123
Received:
12 September 2020
Accepted:
24 September 2020
Published:
17 October 2020
Abstract: According to past studies, Nigerian Bentonites are found to be deficient in both fluid loss and rheological properties. Due to the deficiency of the Nigerian bentonite (NB), a good majority of bentonites used within Nigeria are imported. This research work seeks to evaluate the economic profitability of beneficiating the fluid loss and rheological properties of NB using periwinkle shell (PWS) and Mucuna Solannie (MS) as additives. The economic evaluation of this research seeks to point out the best possible action, based on available evidence. Two parameters—cost and outcome, are measured by the economic evaluation. From this measurement, an economic evaluation’s results will not exactly point out the better alternative, the way that an experimental trial would. If the most effective option from the evaluation is the cheapest, then it is the most cost effective option. In such a scenario, the most cost effective option is said to be the dominant alternative. From the economic evaluation of the PWS and MS additives performed during the course of this research, it can be said that these additives are economically profitable when added to local bentonite (LB), compared to the cost of using imported bentonite (IB) clay. Estimation of required equipment and facility for processing of additives (PWS and MS), calculation of discounted cash flow rate of return (DCF – ROR) for the investment and sensitivity analysis on the cash flow assumptions were carried out for the achievement of optimum results.
Abstract: According to past studies, Nigerian Bentonites are found to be deficient in both fluid loss and rheological properties. Due to the deficiency of the Nigerian bentonite (NB), a good majority of bentonites used within Nigeria are imported. This research work seeks to evaluate the economic profitability of beneficiating the fluid loss and rheological ...
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