The reasonable breaking location of overhanging hard roof for directional hydraulic fracturing to control strong strata behaviors of gob-side entry

Huang, Bingxiang; Liu, Changyou; Zhang, Quan

doi:10.1016/j.ijrmms.2018.01.013

Cited by 105 publications

(52 citation statements)

References 4 publications

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“…The HHR satisfies the thin-plate theory requirement, and the roof breakage problem can be studied according to Kirchhoff's hypothesis. 38 Based on the theory of plates and shells, 14 the HHR for a continuous mining face can be approximately regarded as an elastic rectangular thin plate with two clamped edges and two simply supported edges, as shown in Figure 6.…”

Section: Periodic Fracture Span Of Hhrmentioning

confidence: 99%

“…where K g is the load transfer coefficient. According to the stress equilibrium theory of loosened material, 49 the width s of the stress limit equilibrium zone and seam interface stress σ y are, 14 respectively.…”

Section: Criterion For the Hhr Supported By Caved Rocksmentioning

confidence: 99%

“…The problem of hard roof control has been hotly debated in research on mine disaster prevention. [14][15][16] As hard roofs are notoriously difficult to collapse, control technologies have been studied since 1951, and a series of hard roof control theories and technological methods have been developed. [17][18][19] At present, the most commonly used technologies are coal pillar supports, gob-side entry retention, goaf filling, a spatiotemporal coupling fracturing method using a nonexplosive expansion material, water injection to weaken the roof, presplitting blasting, deep hole blasting, energy-cavity blasting, and hydraulic slitting.…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19] At present, the most commonly used technologies are coal pillar supports, gob-side entry retention, goaf filling, a spatiotemporal coupling fracturing method using a nonexplosive expansion material, water injection to weaken the roof, presplitting blasting, deep hole blasting, energy-cavity blasting, and hydraulic slitting. 2,14,15,[20][21][22][23][24][25][26][27][28] The main ideas can be summarized as follows: (a) maintain the stability of the hard roof and support the stope space; (b) weaken the hard roof and reduce its rock mass strength; and (iii) transfer the stress or release the strain energy to eliminate the source of SGP.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Pan

Xia

et al. 2020

Energy Science & Engineering

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Traditional methods of controlling hard roofs have a limited scope of action and cannot effectively release the strong ground pressure behavior (SGPB) induced by high-position hard roofs (HHRs) in extra-thick coal seam mining (ETCSM). Thus, an innovative control technology of fracturing HHRs by vertical-well stratified fracturing (VWSF) has been proposed. However, the key parameters of VWSF, namely fracturing horizon and fracturing thickness of HHRs, which have a significant influence on stope stability, remain uncertain. In this study, a mechanical model of the "coal wall-hydraulic support-gangue" support system is established by considering the effective loading acting on HHRs, through which modified expressions for the periodic breaking span and impact kinetic energy of the stope are deduced. Based on the self-bearing of bulking rocks, the stability principle of the surrounding rock, and energy dissipation theories, the criteria for determining the fracturing horizon and thickness of the HHR are obtained. Next, a numerical model of ETCSM, which accounts for the supporting effect of gangue, is constructed in FLAC3D. The support load and energy released by stratum breakage are determined through modeling under various hard roof parameters, thus verifying the correctness of the determination criteria. The results show that the energy released by a hard roof, average support load, and critical support load are positively correlated with thickness, and first increase before declining with respect to an increase in the fracturing horizon.The key parameters for a real coal mine are obtained by theoretical calculations and numerical simulations. A field application demonstrates that the support load and advance roadway deformation can be decreased using the proposed parameterization. This provides theoretical support for determining the key parameters of HHRs for VWSF and facilitates the widespread application of VWSF technology in HHR control. K E Y W O R D Shigh-position hard roofs, microseismic monitoring, mine safety, strong ground pressure behavior, vertical-well stratified fracturing | 2217 PAN et Al.

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Section: Periodic Fracture Span Of Hhrmentioning

confidence: 99%

Section: Criterion For the Hhr Supported By Caved Rocksmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Pan

Xia

et al. 2020

Energy Science & Engineering

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show abstract

“…Yu et al [44] proposed the fracturing high-level hard rock strata using the ground hydraulic action. To achieve pressure relief of the entry nearby the side of the gob, the reasonable length and fracture location of the lateral cantilever structure were determined by mechanical analysis, but the influences of remolded structures by human on the movement of the upper structures was not considered [45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

et al. 2019

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Due to the additional abutment stress, interactional hard roof structures (IHRS) affect the normal operation of the coal production system in underground mining. The movement of IHRS may result in security problems, such as the failure of supporting body, large deformation, and even roof caving for nearby openings. According to the physical configuration and loading conditions of IHRS in a simple two-dimensional physical model under the plane stress condition, mining-induced failure criteria were proposed and validated by the mechanical behavior of IHRS in a mechanical analysis model. The results indicate that IHRS, consisting of three interactional parts-the lower key structure, the middle soft interlayer, and the upper key structure-are governed by the additional abutment stress induced by the longwall mining working face. The fracture of the upper key structure in IHRS can be explained as follows: Due to the crushing failure, lower key structure, and middle soft interlayer yield, the action force between the upper and lower key structures vanishes, resulting in fracture of the upper key structure in IHRS. In a field case, when additional abutment stress reaches 7.37 MPa, the energy of 2.35 × 10 5 J is generated by the fracture of the upper key structure in IHRS. Under the same geological and engineering conditions, the energy generated by IHRS is much larger than that generated by a single hard roof. The mining-induced failure criteria are successfully applied in a field case. The in-situ mechanical behavior of the openings nearby IHRS under the mining abutment stress can be clearly explained by the proposed criteria.

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Research on high‐pressure abrasive water jet slotting and pressure relief technology for hard rock roof

Zhenfei,

Wenbin

2024

Energy Science & Engineering

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To solve the problem of severe rock pressure near coal mining face tunnels, a high‐pressure abrasive water jet slotting and roof breaking pressure relief technology is proposed. First, the laneway deformation mechanism and the process of hard rock slotting using high‐pressure abrasive water jets under long‐distance cantilever conditions are analyzed, and the crack initiation conditions of roof strata are obtained. Second, slotting tests under different slotting pressures, nozzle diameters, abrasive particle sizes and slotting times were carried out, and the slotting parameters of a high‐pressure abrasive water jet on a typical roof rock were obtained. Finally, industrial application was carried out in the 81,403 working face of Huayang No.1 Mine. After the hydraulic roof slotting measures were implemented in the test area, the maximum axial force of the anchor cable was reduced to 67 kN, which was 35.5% lower than that of the comparison. The average stress of the coal seam was 15 MPa, which was approximately 25% lower than that of the comparison. The deformation of the tunnel in the experimental area was significantly controlled, with an average movement of 30.0% toward the roof and floor of the tunnel and an average movement of 23.2% toward the two sides of the tunnel. Compared with the movement in the comparison section, the movement toward the roof and floor of the laneway was 42.3% lower, and the movement toward the two sides was 38.2% lower. The industrial application results show that high‐pressure abrasive water jet roof slotting and pressure relief technology can cut off the stress transmission path between the roof rock on both sides, effectively improve the stress state of the surrounding rock of the laneway, reduce the deformation of the roof, floor and two sides of the working face in the later stage of the mining laneway.

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The reasonable breaking location of overhanging hard roof for directional hydraulic fracturing to control strong strata behaviors of gob-side entry

Cited by 105 publications

References 4 publications

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Determination of the key parameters of high‐position hard roofs for vertical‐well stratified fracturing to release strong ground pressure behavior in extra‐thick coal seam mining

Mining-Induced Failure Criteria of Interactional Hard Roof Structures: A Case Study

Research on high‐pressure abrasive water jet slotting and pressure relief technology for hard rock roof

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