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

Zhang, Ningbo; Chen, Baobao

doi:10.3390/en11061363

Cited by 7 publications

(8 citation statements)

References 27 publications

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“…e presplitting blasting of the overlying strata on the 72908 haulage roadway is shown in Figure 12(b). According to previous engineering experience [33][34][35], the space between the presplitting blasting borehole is generally in the range of 400-600 mm. e numerical simulation was carried out on the rock strata conditions of the #2 coal seam in Du'erping coal mine.…”

Section: Determination Of the Best Blasting Parametersmentioning

confidence: 99%

Study on Presplitting Blasting the Roof Strata of Adjacent Roadway to Control Roadway Deformation

Yang

et al. 2019

Shock and Vibration

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In order to solve the problem of roadway deformation based on the theory of “short cantilever beam by roof cutting,” the method of “pressure relief by roof cutting in the adjacent roadway” is proposed. Through presplitting blasting the roadway hard rock layer, the stress propagation path is cut off, and the surrounding rock stress environment of the roadway is improved, to achieve the purpose of controlling the deformation of the roadway caused by stress. Through theoretical analysis, it is determined that the depth of the presplitting blasthole is 17 m, and the angle with the vertical direction is 10°. Based on in situ measurements and tests, by presplitting blasting the roof strata of the adjacent roadway, the maximal value of the working resistance of the hydraulic support in the presplitting blasting side of the working face decreased by 24.9%, and the average volumes of the maximum floor heave, the maximum roof subsidence, and the maximum ribs displacement were reduced by 50.1%, 34.9%, and 41.7%, respectively. This method completely changes the traditional thought patterns of “reinforcing support” to control roadway deformation from “strong support” to “pressure relief.” It provides a new idea for controlling the roadway deformation.

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Section: Determination Of the Best Blasting Parametersmentioning

confidence: 99%

Study on Presplitting Blasting the Roof Strata of Adjacent Roadway to Control Roadway Deformation

Yang

et al. 2019

Shock and Vibration

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“…[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%

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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“…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. However, when using hydraulic fracturing for a hard roof, the mechanical properties of the roof decrease through the interaction of rock and water [25,26]. erefore, blasting presplitting is generally used for a hard roof.…”

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

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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.

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

Cited by 7 publications

References 27 publications

Study on Presplitting Blasting the Roof Strata of Adjacent Roadway to Control Roadway Deformation

Study on Presplitting Blasting the Roof Strata of Adjacent Roadway to Control Roadway Deformation

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

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

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