A Control Approach of the Roof in No-Pillar Roadway Formed by Roof Cutting and Pressure Releasing

Lou, Qingnan; Li, Tingchun; Zhu, Qingwen; Wu, Shanyuan; Yun, Ming; Zhao, Renle

doi:10.1155/2021/4303021

Cited by 7 publications

(6 citation statements)

References 33 publications

(35 reference statements)

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“…To verify the theoretical calculations and simulation results, a field test was conducted. A KJ-24 wireless mine pressure monitoring system was used in the field for monitoring (Lou et al, 2021). The monitoring location diagram is shown in Figure 12.…”

Section: Field Monitoring Schemementioning

confidence: 99%

Research on the coupled support technology of a composite rock beam-retained roadway roof under close coal seams

Li,

Yang,

Zhu

et al. 2023

Front. Ecol. Evol.

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IntroductionThe technology of gob-side entry retaining without coal pillars in close (distance) coal seams is still immature, and the roof control and support technology in this case is not perfect.MethodsIn this paper, the coupled support technology of a composite rock beam roof under close coal seams is systematically studied by using theoretical analysis, numerical simulation and field test.ResultsBoth the floor slip calculation results and numerical simulations indicate that the vertical failure depth in the plastic zone of the #8 coal seam has not penetrated the roof of the #9 coal seam after mining, which is consistent with the field electronic imaging results. A theoretical formula for a composite rock beam model anchored by high-prestressed anchor cables was derived, and a formula for the optimal spacing of anchor cables under noncompressive shear failure of the roof was obtained. Identification of the internal stress hazard region of the rock beam provides a basis for determining the locations of vertical support. Through numerical simulation of different support schemes, including roof cutting, arrangement of high-prestressed anchor cables, and setting up of vertical supports, roof cutting was found to effectively reduce the stress of supporting structure and roof pressure. Setting up of vertical supports can reduce the roof convergence by 25.2%, and coupling with anchor cables can reduce the convergence by more than 49.1%. The feasibility of this support scheme was verified through field tests, with a maximum convergence of 99 mm between the roof and floor.DiscussionThis two-way verification approach, in which the damage degree of the roof of a close coal seam is analyzed through multiple means, targeted support plans are proposed, the support mechanisms are explored, and feedback is conducted through field tests, plays a certain guiding role in solving roof control of the gob-side entry retaining under similar geological conditions.

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Section: Field Monitoring Schemementioning

confidence: 99%

Research on the coupled support technology of a composite rock beam-retained roadway roof under close coal seams

Li,

Yang,

Zhu

et al. 2023

Front. Ecol. Evol.

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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%

“…Unlike the traditional gob-side entry retention, the gob-side entry retaining by roof cutting cuts off the roof strata of the roadway and the gob using bidirectional concentrated blasting technology [1][2][3]. After the working face is mined, the roof strata of the gob collapse and form a new rib.…”

Section: Introductionmentioning

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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“…Their major innovation was the elimination of filling materials. GERRC uses presplit blasting to change the stress distribution and uses the features of broken and caving gangue expansion to achieve the GER 12,13 …”

Section: Introductionmentioning

confidence: 99%

“…GERRC uses presplit blasting to change the stress distribution and uses the features of broken and caving gangue expansion to achieve the GER. 12,13 As a new mining technology developed in recent years, 14 GERRC has become a requirement for building green mines. 15 Many scholars and technicians are exploring the parameters of presplitting and roadway support in different geological conditions from the aspects of theoretical analysis, numerical simulation, similar experiments, and engineering tests.…”

Section: Introductionmentioning

confidence: 99%

Research on gob‐side entry‐retaining technology with coal rib and corner strengthened support in soft rock strata

Zhu

Lou

et al. 2023

Energy Science & Engineering

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The gob‐side entry‐retaining by roof cutting and pressure relief (GERRC) method is an advanced no‐pillar mining method that can significantly improve coal recovery and reduce roadway accidents. However, according to case studies, there is relatively little research on the application of the GERRC method in geological conditions of soft rock formations (especially when the roof and floor are both mudstone), and such research is needed. Therefore, based on the typical soft strata of the Xinyi Coal Mine, this paper analyzes the failure mechanism of the roadways and proposes the GERRC method with coal rib and corner strengthened support (CRCSS). The evaluation indexes of the roof convergence rate and cable safety margin are established, and the effects of roof cutting and CRCSS on roadway deformation control are explored by a numerical comparison test. The results show that roof cutting has a limited effect on roadway deformation. The deformation can be reduced by 75.77% by implementing CRCSS on the basis of GERRC. Then, the evolution characteristics of roadway stress and deformation in the process of mining are further discussed through field contrast tests. The field application results show that compared with that of GERRC with conventional support, the surrounding rock deformation of GERRC with CRCSS is reduced by more than 55%, the safety margin of the cable is improved. The overpressure of the hydraulic prop is diminished, and the stability distance of the roadway is reduced by approximately 30%. Finally, this paper discusses the mechanism to control roadway deformation by CRCSS. This research expounds the rationality of CRCSS, and the results can provide a reference for other situations with similar geological conditions.

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A Control Approach of the Roof in No-Pillar Roadway Formed by Roof Cutting and Pressure Releasing

Cited by 7 publications

References 33 publications

Research on the coupled support technology of a composite rock beam-retained roadway roof under close coal seams

Research on the coupled support technology of a composite rock beam-retained roadway roof under close coal seams

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

Research on gob‐side entry‐retaining technology with coal rib and corner strengthened support in soft rock strata

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