Surrounding Rock Deformation Mechanism and Control Technology for Gob-Side Entry Retaining with Fully Mechanized Gangue Backfilling Mining: A Case Study

Gong, Pan; Ma, Zhuang; Zhang, Ray Ruichong; Ni, Xiaomin; Liu, Fei; Huang, Zhimin

doi:10.1155/2017/6085941

Cited by 40 publications

(28 citation statements)

References 20 publications

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“…Zhang et al [19] studied the effect of different thicknesses of immediate roof on the deformation and fracture characteristics of roof in gob-side entry, and deduced a formula of rational support resistance of RSB. Gong et al [20] analyzed the effect of initial compaction of BFA on the deformation of retained entry roof and the stability of RSB by using physical simulation, which demonstrated the decisive effect of BFA granular gangue on the control of main roof deformation. Meanwhile, a RSB structure containing a flexible cushion was proposed, which can maintain a certain support force while adapting to the bending deformation of the roof, isolating crushed gangue from the gob, and limiting the deformation of the immediate roof.…”

Section: Introductionmentioning

confidence: 99%

Floor Heave Mechanism of Gob-Side Entry Retaining with Fully-Mechanized Backfilling Mining

Gong

et al. 2017

Energies

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Serious floor heave in gob-side entry retaining (GER) with fully-mechanized gangue backfilling mining affects the transportation and ventilation safety of the mine. A theoretical mechanical model for the floor of gob-backfilled GER was established. The effects of the mechanical properties of floor strata, the granular compaction of backfilling area (BFA), the vertical support of roadside support body (RSB), and the stress concentration of the solid coal on the floor heave of the gob-backfilled GER were studied. The results show that the floor heave increases with the increase of the coal seam buried depth, and decreases with the increase of the floor rock elastic modulus. The development depth of the plastic zone decreases with the increase of the c and φ value of the floor rock, and increases with the increase of the stress concentration factor of the solid coal. The development depth of the plastic zone in the test mine reached 2.68 m. The field test and monitoring results indicate that the comprehensive control scheme of adjusting backfilling pressure, deep grouting reinforcement, shallow opening stress relief slots, and surface pouring can effectively control the floor heave. The roof-floor displacement is reduced by 73.8% compared to that with the original support scheme. The roadway section meets the design and application requirements when the deformation stabilizes, demonstrating the rationality of the mechanical model. The research results overcome the technical bottleneck of floor heave control of fully-mechanized backfilling GER, providing a reliable basis for the design of a floor heave control scheme.

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Section: Introductionmentioning

confidence: 99%

Floor Heave Mechanism of Gob-Side Entry Retaining with Fully-Mechanized Backfilling Mining

Gong

et al. 2017

Energies

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“…Gob-side entry retaining can enhance the coal recovery rate, reduce roadway drivage ratios and extend the service life of a mine. In general, an artificial wall is needed on the gob side of the entry so that the cross section of retained entry can still satisfy the service requirement after deformation [24]. During the early stage of C1661 mining, bagged gangue is used as the retaining wall along the side of a roadway, as shown in Figure 12.…”

Section: Gob-side Entry Retainingmentioning

confidence: 99%

A New Thin Seam Backfill Mining Technology and Its Application

et al. 2017

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Abstract:Backfill mining is an effective way to control ground subsidence and govern gangue. To solve the problem of thin coal seam mining under villages, a new thin seam backfill mining technology was proposed. This paper investigated a reasonable proportion of filling materials by experiments, designed the filling system and introduced key technologies for thin seam working face filling. Finally, an industrial test of thin seam backfill mining technology was carried out in the C1661 working face, Beixu Coal Mine. The results show that the developed filling material meets both the pumping liquidity and strength requirements of the filling body during the early and late stages. The design and equipment selection of the paste filling system were reasonable. By using the key technologies for thin seam working face filling, the time needed for working face filling, the connection and disconnection of the filling pipeline and gob-side entry retaining were all greatly shortened. The labor intensity of the workers was reduced, and the mechanization level of the mine was improved. A fill mining length of 480 m was successfully completed. With effective roof subsidence control, the ground subsidence can be reduced, and good results can be achieved. This study can contribute to the development of backfill mining in thin coal seams.

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“…In recent years, a great deal of research into RGE for FMLP has been carried out [5][6][7][8][9][10]. Many studies have indicated that the deformation and stress distribution of roadside backfilling body (RBB) play an important role in RGE [11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Vertical Stress and Deformation Characteristics of Roadside Backfilling Body in Gob-Side Entry for Thick Coal Seams with Different Pre-Split Angles

et al. 2019

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Retained gob-side entry (RGE) is a significant improvement for fully-mechanized longwall mining. The environment of surrounding rock directly affects its stability. Roadside backfilling body (RBB), a man-made structure in RGE plays the most important role in successful application of the technology. In the field, however, the vertical deformation of RBB is large during the panel extraction, which leads to malfunction of the RGE. In order to solve the problem, roof pre-split is employed. According to geological conditions as well as the physical modeling of roof behavior and deformation of surrounding rock, the support resistance of RBB is calculated. The environment of surrounding rock, vertical stress and vertical deformation of the RBB in the RGE with different roof pre-split angles are analyzed using FLAC 3D software. With the increase of roof pre-split angle, the vertical stresses both in the coal wall and RBB are minimum, and the vertical deformation of RBB also decreases from 110.51 mm to 6.1 mm. Therefore, based on the results of numerical modeling and field observation, roof pre-split angle of 90 • is more beneficial to the maintenance of the RGE.Energies 2019, 12, 1316 2 of 16 deformation. Using the numerical simulation, break position and shape of the main roof along the RGE, the influence of different support methods on the roof movement and the relevant technical parameters of RBB were analyzed [18,19]. Tan et al. (2015) studied the stability of RBB under hard roof condition by using flexible-hard support model for RGE [20]. Zhang et al. (2015) analyzed high-water packing materials in RGE using numerical analysis, and the optimal width of the RBB was analyzed [21].There are also many studies involving problems in using the technology, such as serious deformation of RBB [22][23][24]. Using the dynamic analysis software LS-DYNA (Livermore Software Technology Corporation, Livermore, CA, USA) and theoretical analysis, Gao et al. (2013) analyzed the pressure relief mechanism of the induced roof caving by deep-hole blasting. It was found that the deep-hole-blasting can effectively reduce the load transferred to RBB and is more conducive to the maintenance of RGE [25]. Zhao et al. (2015) proposed the optimal control technology of surrounding rock structure through the following methods. First, the hard roof ahead of the working face is pre-split using deep holes. Then overhanging roof at gob side is broken so as to release the pressure by deep-hole blasting. The control technology has been successfully applied in Pingdingshan No. 12 coal mine [26]. Sun et al. studied the key parameters including height, angle, and length of deep-holes for roof breakage and pressure relief [27].However, most studies on RGE are against thin coal seam mining. It has been shown that RGE can achieve good results in thin coal seams. However, in thick coal seams using the fully mechanized longwall top coal caving (FMLTCC), the situation of the RBB is quite different. In this paper, using FLAC 3D (Itasca: Minneapolis, MN, USA), vert...

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Surrounding Rock Deformation Mechanism and Control Technology for Gob-Side Entry Retaining with Fully Mechanized Gangue Backfilling Mining: A Case Study

Cited by 40 publications

References 20 publications

Floor Heave Mechanism of Gob-Side Entry Retaining with Fully-Mechanized Backfilling Mining

Floor Heave Mechanism of Gob-Side Entry Retaining with Fully-Mechanized Backfilling Mining

A New Thin Seam Backfill Mining Technology and Its Application

Vertical Stress and Deformation Characteristics of Roadside Backfilling Body in Gob-Side Entry for Thick Coal Seams with Different Pre-Split Angles

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