Field study on the load transfer mechanics associated with longwall coal retreat mining

Kang, Huan; Wu, Le; Gao, Fuqiang; Lv, Huawen; Li, Jianzhong

doi:10.1016/j.ijrmms.2019.104141

Cited by 33 publications

(14 citation statements)

References 10 publications

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“…It is located on the bank of the Ulan Mulun River at the southern end of Daliuta town in Shenmu County, Shaanxi Province, China. The annual production capacity of the Huojitu coal mine is 5 million tons, the minefield area is 63 km 2 , the geological reserves are 950 million tons, and the recoverable reserves are 624 million tons. Its location is presented in Figure 1.…”

Section: Engineering Backgroundmentioning

confidence: 99%

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Comprehensive Study on Surrounding Rock Failure Characteristics of Longwall Roadway and Control Techniques

Yang

Huang

et al. 2021

Applied Sciences

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Research on underground coal mines has primarily focused on the stability of roadways. Mining activities lead to significant damage to the surrounding rocks and also degrade the support to the roadways. Considering the 21309 roadway of the Huojitu coal mine as a case study, this work comprehensively analyzed the characteristics of the surrounding rock using three methods: theoretical calculations, FLAC3D numerical modeling, and field observations. The results indicate that, under the influence of secondary mining, the failure range and stress concentration degree of the surrounding rock are considerably higher than those under the influence of primary mining. In this case, the maximum damage range in the surrounding rock can reach 1.8 m, the maximum principal stress can reach 19.82 MPa, and the ratio of the maximum principal stress to the minimum principal stress can reach 1.95. According to the results, the previous support design for roadways was optimized and applied in the field. Field monitoring revealed that the roadway deformation was effectively controlled, and the optimized support design was safe and reliable. This study is expected to serve as a reference for support designs or optimization under similar geological conditions.

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Section: Engineering Backgroundmentioning

confidence: 99%

“…To solve the problems associated with transportation, ventilation, and gases, many underground coal mines in China still employ a two-entry longwall panel system [1,2]. The roadway in this system is subjected to two mining influences and strong ground pressure behaviors; consequently, roadway maintenance is more difficult [3,4].…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Study on Surrounding Rock Failure Characteristics of Longwall Roadway and Control Techniques

Yang

Huang

et al. 2021

Applied Sciences

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“…In the past few decades, extensive research has been conducted on distribution of the mining-induced stress in longwall panels. The most commonly used research methods include theoretical calculation (Rezaei et al 2015;Wu et al 2012;Xie et al 2015;Yang and Xie 2010), numerical simulation Guo et al 2012;Islam et al 2009;Wang et al 2013), and field measurements (Kaiser et al 2001;Kang et al 2019a;Kelly et al 2002;Sinha and Walton 2019;Wang et al 2015b;Xia et al 2011). Some consensus has been reached.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of evolution of mining-induced stress field in the longwall panel: insights from physical modeling

Lou

Fu-qiang

Yang

et al. 2021

Int J Coal Sci Technol

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The evolution of mining-induced stress field in longwall panel is closely related to the fracture field and the breaking characteristics of strata. Few laboratory experiments have been conducted to investigate the stress field. This study investigated its evolution by constructing a large-scale physical model according to the in situ conditions of the longwall panel. Theoretical analysis was used to reveal the mechanism of stress distribution in the overburden. The modelling results showed that: (1) The major principal stress field is arch-shaped, and the strata overlying both the solid zones and gob constitute a series of coordinated load-bearing structures. The stress increasing zone is like a macro stress arch. High stress is especially concentrated on both shoulders of the arch-shaped structure. The stress concentration of the solid zone in front of the gob is higher than the rear solid zone. (2) The characteristics of the vertical stress field in different regions are significantly different. Stress decreases in the zone above the gob and increases in solid zones on both sides of it. The mechanical analysis show that for a given stratum, the trajectories of principal stress are arch-shaped or inversely-arched, referred to as the “principal stress arch”, irrespective of its initial breaking or periodic breaking, and determines the fracture morphology. That is, the trajectories of tensile principal stress are inversely arched before the first breaking of the strata, and cause the breaking lines to resemble an inverted funnel. In case of periodic breaking, the breaking line forms an obtuse angle with the advancing direction of the panel. Good agreement was obtained between the results of physical modeling and the theoretical analysis.

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“…Basarir et al 14 applied the global–local modeling approach to analyze the stability of the longwall roadways, which is applicable for roadways experiencing large convergence. Kang et al 15 indicated the front abutment stresses ahead of the coalface based on the load transfer mechanics. Esterhuizen et al 16 developed a numerical model to analyze tailgate stability at two longwall mines based on the field monitoring data.…”

Section: Introductionmentioning

confidence: 99%

Finite-difference based response surface methodology to optimize tailgate support systems in longwall coal mining

Mahdevari

Hayati

2021

Sci Rep

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Designing a suitable support system is of great importance in longwall mining to ensure the safe and stable working conditions over the entire life of the mine. In high-speed mechanized longwall mining, the most vulnerable zones to failure are roof strata in the vicinity of the tailgate roadway and T-junctions. Severe roof displacements are occurred in the tailgate roadway due to the high-stress concentrations around the exposed roof span. In this respect, Response Surface Methodology (RSM) was utilized to optimize tailgate support systems in the Tabas longwall coal mine, northeast of Iran. The nine geomechanical parameters were obtained through the field and laboratory studies including density, uniaxial compressive strength, angle of internal friction, cohesion, shear strength, tensile strength, Young’s modulus, slake durability index, and rock mass rating. A design of experiment was developed through considering a Central Composite Design (CCD) on the independent variables. The 149 experiments are resulted based on the output of CCD, and were introduced to a software package of finite difference numerical method to calculate the maximum roof displacements (dmax) in each experiment as the response of design. Therefore, the geomechanical variables are merged and consolidated into a modified quadratic equation for prediction of the dmax. The proposed model was executed in four approaches of linear, two-factor interaction, quadratic, and cubic. The best squared correlation coefficient was obtained as 0.96. The prediction capability of the model was examined by testing on some unseen real data that were monitored at the mine. The proposed model appears to give a high goodness of fit with the accuracy of 0.90. These results indicate the accuracy and reliability of the developed model, which may be considered as a reliable tool for optimizing or redesigning the support systems in longwall tailgates. Analysis of variance (ANOVA) was performed to identify the key variables affecting the dmax, and to recognize their pairwise interaction effects. The key parameters influencing the dmax are respectively found to be slake durability index, Young’s modulus, uniaxial compressive strength, and rock mass rating.

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Field study on the load transfer mechanics associated with longwall coal retreat mining

Cited by 33 publications

References 10 publications

Comprehensive Study on Surrounding Rock Failure Characteristics of Longwall Roadway and Control Techniques

Comprehensive Study on Surrounding Rock Failure Characteristics of Longwall Roadway and Control Techniques

Characteristics of evolution of mining-induced stress field in the longwall panel: insights from physical modeling

Finite-difference based response surface methodology to optimize tailgate support systems in longwall coal mining

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