Fracture analysis of double-layer hard and thick roof and the controlling effect on strata behavior: A case study

Ning, Jianguo; Wang, Jun; Jiang, Lishuai; Ning, Jianguo; Liu, Xuesheng; Jiang, Jinquan

doi:10.1016/j.engfailanal.2017.07.029

Cited by 67 publications

(48 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A stress-monitoring point was arranged in increments of eight supports, i.e., on support Nos. 3,11,19,27,35,43,51,59,67,75,83,91, and 99 for on-line real-time monitoring of the stress data.…”

Section: Stress Monitoring Of Supportsmentioning

confidence: 99%

“…When a hard, thick, main roof occurs over a coal seam where no immediate roof is present or the immediate roof is thinner, the wall beside the roadway may have difficulty in supporting the hard roof. erefore, it is necessary to presplit the hard roof and to change the main roof structure, thus resulting in effective pressure alleviation of the GSE [18][19][20][21][22]. At present, commonly used methods for roof presplitting are blasting presplitting and hydraulic fracturing [23,24], which can effectively cut off the overhanging roof above the retaining roadway and result in roof caving.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Analysis of Overburden Structure and Pressure‐Relief Effect of Hard Roof Blasting and Cutting

Liu

Dai

Jiang

et al. 2019

Advances in Civil Engineering

Self Cite

View full text Add to dashboard Cite

When studying the pressure-relief effect of hard roof blasting and cutting, the roof-cutting position and angle obviously affect the stability of the rock surrounding the gob-side entry (GSE). In this paper, control of the large deformation of rock surrounding the GSE is evaluated on the basis of the overlying structure and pressure-relief principle caused by roof cutting. Moreover, a mechanics model of a three-hinged arch structure (THAS) and a universal distinct element code (UDEC) numerical model with regard to the overlying rock movement were established to study the relationship among the rotation angle of key blocks in the THAS, the width of the roadway and the wall force beside it, and the optimal cutting position and cutting angle to reveal the pressure-relief effect of roof blasting and cutting and its influence on the support stability of the roadway. The results show that the overlying rock can form a stable THAS after roof blasting and cutting and that the wall stress and the coal-wall displacement are small, which indicates that roof blasting and cutting results in obvious pressure relief. The wall force increases with an increase in the rotation angle of the key block and decreases with an increase in the roadway width. Moreover, the optimal roof-cutting position (5 m) and angle (15°) are obtained with the specific mining conditions. Finally, on-site monitoring of the anchor-cable force and support force in panel 5312 of the Jining no. 3 coal mine is used to verify the pressure-relief effect after roof blasting and cutting. The study results can provide a theoretical basis for reasonable technical means and optimization of supporting parameters in field observation and have important application value for roof cutting and pressure relief for GSE retaining (GSER) technology.

show abstract

Section: Stress Monitoring Of Supportsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analysis of Overburden Structure and Pressure‐Relief Effect of Hard Roof Blasting and Cutting

Liu

Dai

Jiang

et al. 2019

Advances in Civil Engineering

Self Cite

View full text Add to dashboard Cite

show abstract

“…The coal mining process results in a large-scale HMR hanging in the gob, which is difficult to collapse naturally. A sudden collapse of this roof when the area of hanging roof reaches a certain value would be disastrous and could result in a shock wave or hurricane, for example [5][6][7]. Following this, mining equipment would be seriously damaged, the normal mining activities would be terminated, and casualties would occur [8,9].…”

Section: Introductionmentioning

confidence: 99%

A Case Study of Presplitting Blasting Parameters of Hard and Massive Roof Based on the Interaction between Support and Overlying Strata

Zhang

Chen

2018

Energies

View full text Add to dashboard Cite

Due to the existence of a hard and massive roof (HMR), severe ground pressure behaviors have been observed at the working face, resulting in safety issues and the degradation of production effectiveness. Based on the HMR conditions of the Datong Mining Area, the fracture-related instability of the HMR and its effects on the support selection were investigated by analyzing the interaction between support and overlying strata. Advancefixed-distance presplitting blasting (AFPB) technology was proposed to control the caving interval of HMR, and the influence of the controlled interval on the working load of supports was also analyzed. The working load of the support and the caving interval of the HMR were determined based on the controlled HMR fracture technology, and these were verified by field application tests. The working resistance of the support and the step distance were determined based on controlled roof fracture and were verified by on-site application experiments. The results revealed that cracks emerged after the presplitting blasting, resulting in significantly reduced strata behaviors. Furthermore, the support exhibited good adaptability.

show abstract

“…Large-scale coal bases in China are the northeastern China, the north of Shanxi Province, the east of Shanxi Province, the central part of Shanxi, the central part of Hebei Province, the southwest of Shandong Province, Huainan and Huaibei, Shendong, the north of Shaanxi, Ningdong, Yunnan and Guizhou, as well as the west of Henan Province. In the mining areas of Yulin, located at the north of Shaanxi, Datong and Yangfangkou in the north of Shanxi, Zaozhuang of Shandong province, Tonghua, Hegang, and Qitaihe in northeast of China, and Jingyuan of Huanglong [6][7][8][9][10][11], the problems regarding hard roofs are ubiquitous, among which, the accidents of roof falls account for approximately 70% of the accidents on the working faces.…”

Section: Introductionmentioning

confidence: 99%

“…Guo [8] and Ning [10] successfully solved the problem of severe strata behaviors, caused by ultra-thick hard roofs, through the decompression blasting and deep-hole presplitting blasting methods, respectively. He [21] and Zheng [22] relieved the early-warning of high strata pressure on the working face, guaranteeing safe mining at the working face through the hydrofracturing and sleeve fracturing methods, respectively.…”

Section: Introductionmentioning

confidence: 99%

Study on Fracture and Stress Evolution Characteristics of Ultra‐Thick Hard Sandstone Roof in the Fully Mechanized Mining Face with Large Mining Height: A Case Study of Xiaojihan Coal Mine in Western China

Feng

Xiao

et al. 2018

Advances in Civil Engineering

View full text Add to dashboard Cite

Ultra-thick hard sandstone roofs present high thickness, poor delamination, and wide caving range. The strata pressure of the working face during actual mining increases, having a significant influence on the safe mining of the working face. Especially, in the mining areas of western China, the fully mechanized mining faces with high mining height and high-strength mining are more prominent. Understanding the fractures and stress evolution characteristics of the ultra-thick hard sandstone roof during actual mining is of high significance to control the dynamic pressure on the working face. In this paper, the typical ultra-thick hard sandstone roof of the Xiaojihan coal mine was taken as an example. The structural and chemical composition characteristics were analyzed. Besides, the fracture characteristics of ultra-thick hard roof during the working face mining were analyzed. Moreover, the fracture structure consistency was verified through physical simulation and a field measurement method. Finally, the stress evolution laws in the ultra-thick hard sandstone roof fracture were studied through numerical simulation. The findings demonstrated that (1) the ultra-thick hard sandstone roof was composed of inlaid coarse minerals, which had compact structure, while the Protodyakonov hardness reached up to 3.07; (2) under the high-strength mining condition of fully mechanized mining face with large mining height, the ultra-thick hard sandstone roof had the characteristics of brittle fracture, with a caving span of 12 m; (3) under the high-strength mining condition of fully mechanized mining face with large mining height, the ultra-thick hard sandstone roof followed the stress evolution laws that were more sensitive to the neighboring goaf. Therefore, it was necessary to reduce the fracture span or layering of ultra-thick hard sandstone roof through the manual intervention method adoption or increase either the strength of coal pillar or supporting body, to resist the impact generated during ultra-thick hard sandstone roof fracture.

show abstract

Fracture analysis of double-layer hard and thick roof and the controlling effect on strata behavior: A case study

Cited by 67 publications

References 28 publications

Analysis of Overburden Structure and Pressure‐Relief Effect of Hard Roof Blasting and Cutting

Analysis of Overburden Structure and Pressure‐Relief Effect of Hard Roof Blasting and Cutting

A Case Study of Presplitting Blasting Parameters of Hard and Massive Roof Based on the Interaction between Support and Overlying Strata

Study on Fracture and Stress Evolution Characteristics of Ultra‐Thick Hard Sandstone Roof in the Fully Mechanized Mining Face with Large Mining Height: A Case Study of Xiaojihan Coal Mine in Western China

Contact Info

Product

Resources

About