The effect of burnt rock on inclined shaft in shallow coal seam and its control technology

Yuan, Yue; Liu, Zhiheng; Zhu, Cheng; Yuan, Chunlin; Wang, Sheng‐zhi

doi:10.1002/ese3.398

Cited by 11 publications

(4 citation statements)

References 15 publications

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“…This led to a considerable amount of heat exchange between them, consuming the cold energy released by the low-temperature brine and causing the frozen wall temperature of the medium sand layer to decrease gradually. 3 After 68 days of freezing, the average temperature of the frozen wall within the medium sand layer dropped quickly at a rate of 0.1030 • C/day, while the fine sand layer experienced a reduction rate of 0.0931 • C/day. Considering the freezing speed, the average temperature reduction rate of the frozen wall in the medium sand layer during this stage was higher than that of the frozen wall in the fine sand layer.…”

Section: Average Temperature and Thickness Of The Effective Freezing ...mentioning

confidence: 99%

“…Lately, in China, the development of coal has gradually transitioned to the western region due in large part to the abundant coalfield exploitation in Western China. The region has a straightforward geological composition and shallowly embedded coal seams, making it ideal for the application of inclined-shaft freezing techniques for coal extraction [3].…”

Section: Introductionmentioning

confidence: 99%

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Temporal and Spatial Evolution Laws of Freezing Temperature Field in the Inclined Shaft of Water-Rich Sand Layers

et al. 2023

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This study investigated the distribution and evolution characteristics of the temperature field during the freezing and excavation of inclined shafts, with the freezing open-excavation section of Shengfu Mine’s main inclined shaft (located in Shaanxi Province) as the project background. Utilizing field-measured data and the finite element software COMSOL Multiphysics, a 3D freezing temperature-field numerical calculation model was constructed to examine the temporal and spatial evolutions of the temperature field during the construction of the inclined shaft. The findings showed that after 88 days of freezing, the average temperature of the frozen wall in the open-excavation section was below −12 °C. The frozen wall thickness in the sidewalls of different layers exceeded 4 m, and the thickness at the bottom plate exceeded 5 m, meeting the excavation design requirements. For the same freezing time, the average temperature of the frozen wall in the fine sand layer was 0.28 to 2.39 °C lower than that of the frozen wall in the medium sand layer, and its effective thickness was 0.36 to 0.59 m greater than that in the medium sand layer. When the soil was excavated, and the well side was exposed, a phenomenon known as “heat flow erosion” occurred in the soil at the well-side position, causing the well-side temperature to rise. Nevertheless, this increase was generally limited, and when continuous cooling was applied, the well side could maintain a very low negative temperature level. Consequently, there was no spalling phenomenon. The effective thickness of the frozen wall during excavation did not decrease, with the average temperature remaining below −10 °C. Consequently, there was no large-scale “softening” of the frozen wall during excavation, thus ensuring construction safety. The numerical calculation model in this paper can be used to predict the development law of the freezing temperature field of the water–rich sandy layers in Shengfu Mine and adjust the on–site cooling plan in real time according to the construction progress. This research provides valuable theoretical insights for the optimal design and safe construction of freezing inclined-shaft sinking projects.

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Section: Average Temperature and Thickness Of The Effective Freezing ...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temporal and Spatial Evolution Laws of Freezing Temperature Field in the Inclined Shaft of Water-Rich Sand Layers

et al. 2023

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“…For example, the width of the main roadway in the Lu'an mining area is generally 4.0-5.5 m, and the height is 3.5-4.5 m [20,21]. The general width of the roadway is 5.0-6.5 m and the height is 3.5-4.5 m in the Shandong mining area [22,23]. Accordingly, when the ratio of width to height is less than 1, it is referred to as the small width-to-height ratio in the work.…”

Section: General Engineering Backgroundmentioning

confidence: 99%

Optimal Layout Methods for Deep Chamber to Separate Coal and Gangue Based on the Weak Stratum Horizon

Zhu,

Yuan,

Sun

et al. 2023

Processes

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Aiming at the optimal layout of a deep chamber for coal–gangue separation (DCCS) based on the weak stratum horizon, an in-depth study was carried out by combining field investigations, model tests, and numerical simulations. Firstly, the main structural characteristics of DCCS were summarized. Then, the deformation and failure law for rocks surrounding DCCS were revealed under different horizons in the weak stratum. Finally, the optimal layout methods of DCCS based on the thickness and horizon in the weak stratum were determined in different in situ stresses, using the proposed comprehensive evaluation method for surrounding-rock stability. The results show that if the thickness of the weak stratum was small, the side near the roof of DCCS should be arranged along the weak stratum when the lateral pressure coefficient was λ < 0.6 or λ > 1. The side near the floor of DCCS was arranged along the weak stratum when 0.6 ≤ λ ≤ 1 and the surrounding-rock stability was the best. If the thickness of the weak stratum was large, the side of DCCS should be arranged along the weak stratum when λ < 0.6 or λ > 1. The floor of DCCS was arranged along the weak stratum when 0.6 ≤ λ ≤ 1, which was most favorable for the surrounding-rock control. The research results have important guiding significance for the spatial layout and support design of DCCS.

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“…In northwest China, burnt rocks are widely formed in the coal outcrop area as the shallow buried Jurassic strata (Ma et al, 2021). Yuan et al (2019) have documented that the structure of the burnt rock is damaged with a large number of pores and fractures, which is one of the key factors of instability in the surrounding rock. Xue et al (2021) employed the AHP and entropy-weight method to evaluate the water abundance of BRA and to avoid the recurrence of water inrush during coal mining.…”

Section: Introductionmentioning

confidence: 99%

Effect of Large-Scale Mining Drainage on Groundwater Hydrogeochemical Evolution in Semi-Arid and Arid Regions

Luo

Wang²,

Dong³

et al. 2022

Front. Environ. Sci.

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Groundwater evolution and circulation in coal mining areas will be significantly affected by natural processes and human activities. However, the impacts of large-scale mining drainage on groundwater hydrochemistry are unclear in the semi-arid and arid inland coalfields in northwest China. In particular, for shallow buried areas, the spontaneous combustion of coal seam outcrops forms burnt rock that is rich in fractures. Being a strong water-yield aquifer after receiving recharge, burnt rock has become a potential source of mine water inrush hazards. Therefore, drainage from this aquifer is necessary to eliminate potential hazards, which also leads to the deterioration of the local ecological diversity and sustainability. The hydrogeochemical method is an effective way to study the source and evolution of groundwater in mining areas and to determine the long-term cumulative effect of mining and drainage on the hydrogeochemical evolution of burnt rock areas. It is, however, still poorly understood. In this study, we employed the hydrochemical and isotope (2H, 3H, and 18O) to investigate the long-term effects of drainage on the hydrogeochemical evolution in the coalfield of southern Xinjiang, China. The results showed that the hydrochemical environment became more complex as the effect of recharge of different tritium-based groundwater ages in multiple-layered aquifer system and leads to the changes in the concentration of the chemical components. Before large-scale mining drainage, groundwater flowed from west to east and was finally discharged into the Kuqa River. The major water–rock interactions that occurred were the dissolution of halite, carbonate and gypsum dissolution, cation exchange, and dedolomitization. After large-scale and long-term mining drainage from the burnt rock aquifer, the groundwater flow field had changed, and the Kuqa river turned to recharge into the burn rock aquifer, the hydrochemical evolution also changed from water–rock interaction to mixture. This was caused by the significant decline in the groundwater level and changes in groundwater circulation in the mining area, which further led to the loss of valuable surface water resources in this arid area. Based on the characteristics and recharge conditions of burnt rock, we suggested that grouting can effectively cut off the hydraulic connection between the river and burnt rock and thus protect water resources.

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The effect of burnt rock on inclined shaft in shallow coal seam and its control technology

Cited by 11 publications

References 15 publications

Temporal and Spatial Evolution Laws of Freezing Temperature Field in the Inclined Shaft of Water-Rich Sand Layers

Temporal and Spatial Evolution Laws of Freezing Temperature Field in the Inclined Shaft of Water-Rich Sand Layers

Optimal Layout Methods for Deep Chamber to Separate Coal and Gangue Based on the Weak Stratum Horizon

Effect of Large-Scale Mining Drainage on Groundwater Hydrogeochemical Evolution in Semi-Arid and Arid Regions

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