Presplitting Blasting the Roof Strata to Control Large Deformation in the Deep Mine Roadway

Hu, Chaowen; Yang, Xujing; Huang, Ruifeng; Ma, Xingen

doi:10.1155/2020/8886991

Cited by 12 publications

(7 citation statements)

References 34 publications

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“…The process flow of gob-side entry retaining by roof cutting is shown in Figure 1, (1) In order to ensure the stability of the roadway during the reuse period, high prestressed an-chors are used to support the roof before the working face is mined [12,13]. (2) Bidirectional energy-gathering blasting technology is used to pre-split the roof strata of the roadway, cut off the connection of the roof strata between the roadway and the gob, and ensure that the roof strata collapse in time after the working face is mined to fill the gob and form a new rib of the roadway [2,14]. (3) After the working face is mined, in order to ensure the stability of the roof strata, the roadway is temporarily supported by single pillar [15,16].…”

Section: Key Technology Of Gob-side Entry Retaining By Roof Cutting 2...mentioning

confidence: 99%

Research on the Key Technology of Gob-Side Entry Retaining by Roof Cutting for Thick and Hard Sandstone Roofs

Wang

et al. 2022

Sustainability

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In order to ensure the application of gob-side entry retaining by roof cutting for thick and hard sandstone roofs, the key technology of pre-split blasting was studied. The LS-DYNA was used to analyze the blasting effect of the energy-gathering pipe. Using the methods of theoretical analysis and numerical simulation, it was determined that the optimal cutting height was 16 m and the optimal cutting angle was 15°. The effect of pressure relief by roof cutting was verified by FLAC3D. It is proposed to use deep-hole loosening blasting to solve the problem of the sandstone with a thick hard roof being difficult to collapse. A group of loose blasting holes was designed to be arranged every 20 m in the gob-side roadway. The depth of the #1 blasthole was 47 m, and the angle to the horizontal direction was 20°; the depth of the #2 blasthole was 65 m, and the angle to the horizontal direction was 15°. A field test was carried out in the 7135 ventilation roadway of Qidong Coal Mine China. The on-site peeping results showed that the blasting with the energy-gathering pipe had a good effect of directional slitting. After deep-hole loosening blasting, the thick hard sandstone roof collapsed and filled the gob in time. The monitoring curves of the hydraulic support showed that the hydraulic support resistance of the working face in the side with roof cutting was much smaller than that of the side without roof cutting, and the effect of pressure relief by roof cutting was good.

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Section: Key Technology Of Gob-side Entry Retaining By Roof Cutting 2...mentioning

confidence: 99%

Research on the Key Technology of Gob-Side Entry Retaining by Roof Cutting for Thick and Hard Sandstone Roofs

Wang

et al. 2022

Sustainability

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“…After the roof cutting height, angle, and position all determined, the roof cutting blasting parameters, including explosive charge weight, blasting hole spacing, and blasting hole amount at single initiation, all need to be further got through field blasting test [22,23]. e field blasting test is divided into three steps as shown in Figure 14 [15].…”

Section: Open-off Cut Roof Cutting Processmentioning

confidence: 99%

Research and Application of Open‐Off Cut Roof Cutting Pressure Releasing Technology

et al. 2021

Advances in Civil Engineering

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The first weighting control is one of the difficult problems that cannot be avoided in the safe and efficient production of longwall mining face. To optimize the existing pressure releasing technology of open-off cut, the open-off cut roof cutting pressure releasing (OCRCPR) technology is put forward on the basis of roof cutting pressure releasing gob-side entry retaining (RCPRGER) technology. Firstly, the mechanism of the technology and the design method of related key parameters are summarized. Then the pressure releasing effect of OCRCPR and the stress environment change under this technology are analyzed by mechanics calculation and numerical simulation, respectively, which verify the feasibility of the OCRCPR technology from the theoretical level. Finally, a test mining face is taken as an example to implement the field test. The field test results show that the OCRCPR can effectively shorten the first weighting step and weaken the first weighting strength and has a good pressure releasing effect.

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“…[2,3]. High-stress superposition in deep mines results in serious floor heave problems in mining roadways [4][5][6], which affects mine transportation and the efficient advancement of the working face [7][8][9][10]. An urgent need exists to propose a more rational and effective technology scheme for controlling floor heave in order to promote the sustainable development of gob-side entry retaining technology and resource mining in the coal mining industry.…”

Section: Introductionmentioning

confidence: 99%

The Floor Heave Mechanism and Control Technology of Gob-Side Entry Retaining of Soft Rock Floor

Zhang

et al. 2023

Sustainability

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Extensive soft-rock floor heave in gob-side entry retaining considerably restricts the efficient and sustainable production of the mine. The mechanical capacities of roadway roof and floor strata are discussed through laboratory tests by taking the N2301 fully caving surface auxiliary transport gate road of the Ancient City Coal Mine in the Lu’an Mining Area of Shanxi Province as an engineering background. The stress distribution law of gob-side entry in mining the working surface was explored based on numerical simulation. After that, the mechanical mechanism of floor heave was studied through theoretical analysis. High lead abutment pressure and horizontal stress were superimposed in front of the working surface to cause soft-rock floor heave. The bulk weight of the high overburden was unevenly transmitted to the two sides because of the roof cantilever structure of entry retaining in the rear of the working face. The roadway floor produced an asymmetric sliding force, which caused the occurrence of floor heave. The control technology of floor heave combining the pressure relief of floor blasting and roof cutting was proposed taking account of the mechanism of floor heave. Then, the stress environment of the surrounding rock was improved by the deep hole blasting of the floor. Gob-side roof cutting was used to reduce impact of the bulk weight of the overburden on the surrounding rock deformation of the roadway. A test was conducted after verifying the control effect of blasting pressure relief on roadway floor heave through a similar simulation. Field tests indicated that the maximum floor heave was 168 mm at 250 m in the rear of the working surface, and floor heave was controlled. This study offers a more scientifically sound theoretical reference for controlling floor heave in gob-side entry retaining, which can significantly advance the sustainable development of gob-side entry retaining technology in coal mining.

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Presplitting Blasting the Roof Strata to Control Large Deformation in the Deep Mine Roadway

Cited by 12 publications

References 34 publications

Research on the Key Technology of Gob-Side Entry Retaining by Roof Cutting for Thick and Hard Sandstone Roofs

Research on the Key Technology of Gob-Side Entry Retaining by Roof Cutting for Thick and Hard Sandstone Roofs

Research and Application of Open‐Off Cut Roof Cutting Pressure Releasing Technology

The Floor Heave Mechanism and Control Technology of Gob-Side Entry Retaining of Soft Rock Floor

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