Directional Destress with Tension Blasting in Coal Mines

He, Manchao; Zhang, Xiaohu; Zhao, Shuai

doi:10.1016/j.proeng.2017.05.158

Cited by 24 publications

(13 citation statements)

References 1 publication

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“…As the working face progressed, the immediate roof rock in the gob area gradually collapsed, the gob-side caved gangue gradually became compacted, and a gangue rib eventually formed, as shown in Figure 19a. extension of directional tension failure in the roof-surrounding rock until it propagated into a coalescent fracture plane [26], as shown in Figure 18.…”

Section: The Technique Of Entry Support In Non-pillar Miningmentioning

confidence: 99%

“…Then, a cumulative device and explosive were employed to create a uniform compressive stress on the blast hole wall in non-predefined directions and form a cohesive energy flow that was transmitted in pre-split directions. The directional cohesive energy flow produced concentrated tensile stress, which caused the initiation and extension of directional tension failure in the roof-surrounding rock until it propagated into a coalescent fracture plane [26], as shown in Figure 18.…”

Section: The Technique Of Entry Roof Cutting In Non-pillar Miningmentioning

confidence: 99%

“…Energies 2018, 11, x FOR PEER REVIEW 13 of 17 extension of directional tension failure in the roof-surrounding rock until it propagated into a coalescent fracture plane [26], as shown in Figure 18.…”

Section: The Technique Of Entry Roof Cutting In Non-pillar Miningmentioning

confidence: 99%

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A Case Study on Optimization and Control Techniques for Entry Stability in Non-Pillar Longwall Mining

Yang

Wang

et al. 2019

Energies

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In order to reduce large deformation failure occurrences in non-pillar longwall mining entries due to roof weighting behaviors, a case study in Halagou coal mine was conducted on optimization and control techniques for entry stability in non-pillar longwall mining. The Universal Discrete Element Code (UDEC) modeling was adopted to study entry stability in non-pillar mining, and the characteristics of deformation and stress and crack propagation were revealed. The large deformation transmission between the entry-immediate roof and the gob-immediate roof could be eliminated by optimizing the entry roof structure through a directional roof-cutting method. The localized tensile stresses generated in the entry-surrounding rock caused the generation of coalescent macroscopic fractures, which resulted in the instability of the entry. The tensile stress state could be inhibited by an active flexible support system through enhancing the confining pressure on the surrounding rock. Serious rotation subsidence occurs in the entry roof due to periodic weighting of the main roof, which could be greatly reduced by a passive rigid support pattern. The numerical and field test results both showed that the roof weighting pressure was offloaded by the technique and that the deformation of the entry surrounding the rock in non-pillar mining was quite small. Thus, the technique can effectively ensure the stability of the gob-side entry, which can provide references for entry stability control in non-pillar longwall mining.

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Section: The Technique Of Entry Support In Non-pillar Miningmentioning

confidence: 99%

Section: The Technique Of Entry Roof Cutting In Non-pillar Miningmentioning

confidence: 99%

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A Case Study on Optimization and Control Techniques for Entry Stability in Non-Pillar Longwall Mining

Yang

Wang

et al. 2019

Energies

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“…Second, after reinforcing the entry roof strength, directional presplit blasting is applied to the entry roof ( Figure 3a). The technology utilizes a newly developed point-line energy collecting tube to realize directional control blasting [27][28][29] (Figure 3b), placing the explosive into the device with a concentrating effect in two set directions. After the explosive is detonated, the surrounding rock of the blasthole is subjected to compressive stress in a nonset direction, and the tensile stress works on the set direction, so that the rock body forms a precracking surface according to the set direction.…”

Section: Constant Resistance Large Deformation Anchor Cable (Crldac)mentioning

confidence: 99%

Key Parameters of Roof Cutting of Gob-Side Entry Retaining in a Deep Inclined Thick Coal Seam with Hard Roof

Wang

et al. 2019

Energies

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Gob-side entry retaining by roof cutting (GERRC) employed in a deep inclined thick coal seam (DITCS) can not only increase economic benefits and coal recovery, but also optimize surrounding rock structure. In accordance with the principles of GERRC, the technology of GERRC in DITCS is introduced and a roof-cutting mechanical model of GERRC is proposed to determine the key parameters of the depth and angle of RC. The results show that the greater the RC angle, the easier the caving of the goaf roof, but the length of cantilever beam increases. The depth of RC should account for the dip angle of the coal seam when the angle is above 20°. Increasing the coal seam dip angle could reduce the volume of rock falling of the goaf roof, but increase the filling height of the upper gangue to slide down. According to numerical model analysis of the stress and displacement of surrounding rock at different depths and angles of RC, when the depth of RC increased from 9 m to 13 m, the distance between the stress concentration zone and the coal side is increased. When the angle of RC increased from 0° to 20°, the value of roof separation is decreased. GERRC was applied in a DITCS with 11 m depth and 20° RC angle, and the field-measured data verified the conclusions of the numerical model.

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“…is is used to eliminate the influence of the roadway by cutting the roof in advance, the purpose of unloading roof pressure is achieved, and the low pressure range is increased. In this way, the local stress concentration disappears [5,6]. Han et al studied the mechanism of pressure relief and the structural stability of the transverse cantilever structure of the stope roof.…”

Section: Introductionmentioning

confidence: 99%

Automatic Roadway Backfilling of Caving Gangue for Cutting Roofs by Combined Support on Gob-Side Entry Retaining with No-Pillars: A Case Study

Xie

Chen

et al. 2019

Advances in Materials Science and Engineering

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Automatic roadways on gob-side entry retaining with no-pillars are used for longwall mining technology. The mining technology with no-pillars can recover coal pillar resources and reduce the amount and cost of roadway excavations. Automatic roadway technology for cutting roofs by combined support on gob-side entry retaining with no-pillars is adopted for the condition of thick immediate roof and medium-thick coal seam mining, cutting off the immediate roof and the main roof on the gob by combined support. The fractured roof forms gangue blocks to fill the gob and loads the overlying strata. The gangue control system is placed on the roadside, which controls the caving gangue to form a gangue rib. In this paper, the viewpoints and key technologies (the roof-cutting technology, the reinforcement and support technology, the gangue rib control technology, and the auxiliary support technology) of automatic roadway technology for cutting roofs by combined support on the gob-side entry retaining with no-pillars are introduced. Furthermore, the formation and control process are explained. The numerical simulation is used to simulate and analyze the roof hanging and the roof cutting structures. In addition, a field engineering test is performed. The field test shows that automatic roadway technology for cutting roofs by combined support on gob-side entry retaining with no-pillars is feasible. This process uses construction techniques and technologies to meet on-site production needs. The combined support has high resistance strength and is shrinkable. In engineering applications, the combined support has a low damage rate. The deformation of the automatic roadway with gob-side entry retaining is small, and the control effect is significant.

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Directional Destress with Tension Blasting in Coal Mines

Cited by 24 publications

References 1 publication

A Case Study on Optimization and Control Techniques for Entry Stability in Non-Pillar Longwall Mining

A Case Study on Optimization and Control Techniques for Entry Stability in Non-Pillar Longwall Mining

Key Parameters of Roof Cutting of Gob-Side Entry Retaining in a Deep Inclined Thick Coal Seam with Hard Roof

Automatic Roadway Backfilling of Caving Gangue for Cutting Roofs by Combined Support on Gob-Side Entry Retaining with No-Pillars: A Case Study

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