Numerical Investigation of the Effect of the Location of Critical Rock Block Fracture on Crack Evolution in a Gob-side Filling Wall

Li, Xuehua; Ju, Minghe; Yao, Qiangling; Zhou, Jian; Chong, Zhaohui

doi:10.1007/s00603-015-0783-1

Cited by 116 publications

(58 citation statements)

References 29 publications

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“…Since the retained entry in the zero-pillar mining will experience more dynamic mining disturbances, the entry control techniques appear to be very important. Much research has been conducted on GER applied on thin and medium coal seams regarding the properties and stability of filling bodies [10][11][12], the transfer bearing mechanisms of roofs [13][14][15], and deformation control of retained entries [16][17][18]. Up to now, however, studies of Gob-side entry retaining applied in thick coal seams have rarely seen in the published literatures [19].…”

Section: Introductionmentioning

confidence: 99%

An Innovative Approach for Gob-Side Entry Retaining in Thick Coal Seam Longwall Mining

et al. 2017

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Gob-side entry retaining (GER) is a popular non-pillar mining technique regarding how to reserve a gateroad for the use of next panel mining. When used in thick coal seams, the conventional entry retaining method requires a huge amount of filling materials and may cause entry (gateroad) accidents. Thus, an innovative non-pillar longwall mining approach is introduced. First, structural and mechanical models were built to explore the mechanism of the new approach. The modeling results indicate that effective bulking of the gob roof and reasonable support of the entry roof were key governing factors in improving entry stabilities and reducing roof deformations. Accordingly, a directional roof fracturing technique was proposed to contribute to gob roof caving, and a constant resistance and large deformation anchor (CRLDA) cable was used to stabilize the entry roof. Subsequently, the evolutionary laws of the roof structure and stresses were explored using numerical simulation. It was found that the structure of the surrounding rocks around the retained entry changed significantly after roof fracturing. The stress-bearing center was transferred to the gob area, and the entry roof was in a low stress environment after adopting the approach. Finally, the approach was tested on a thick coal seam longwall mining panel. Field monitoring indicates that the retained entry was in a stable state and the index of the retained entry met the requirement of the next mining panel. This work provides an effective and economical approach to non-pillar longwall mining in thick coal seams.

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Section: Introductionmentioning

confidence: 99%

An Innovative Approach for Gob-Side Entry Retaining in Thick Coal Seam Longwall Mining

et al. 2017

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“…(c) Deformation characteristics of the backfilling body Li et al (2016) [17] investigated crack evolution characteristics in a gob-side filling using the Universal Discrete Element Code software and found that the higher the immediate roof strength is, the fewer cracks are incubated in the filling wall. Ning et al (2014) [18] indicated that the cement-based supporting body beside the roadway would bear a greater roof pressure and a stronger impact load and might easily deform and fail because of its low strength during the early stage.…”

Section: Introductionmentioning

confidence: 99%

“…Currently, research on gob-side entry retaining by backfilling is mainly focused on the deformation characteristics of entry surrounding rocks [5][6][7][8][9][10][11][12], stability control technology [13][14][15][16], parameter determination of backfilling bodies [17][18][19], etc. Some representative research achievements are summarized as follows:…”

Section: Introductionmentioning

confidence: 99%

Roof Deformation Characteristics and Preventive Techniques Using a Novel Non-Pillar Mining Method of Gob-Side Entry Retaining by Roof Cutting

et al. 2018

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Abstract:A new non-pillar mining technology, gob-side entry retaining by roof cutting (GERRC), different from the conventional gob-side entry retaining formed by a roadside filling support, is introduced in this study. In the new technology, roof cutting is conducted so that the roof plate forms a short cantilever beam structure within a certain range above the retained entry, thus changing the stress boundary condition of the roof structure. To explore the deformation characteristics of the roof under this special condition, a short cantilever beam mechanical model was established and solved using energy theory and displacement variational methods. Meanwhile, a theoretical and analytical control solution for roof deformation was obtained and verified via field-measured results. Based on the aforementioned calculation, the relationship between the roof deformation and main influence parameters was explored. It was concluded that the rotation of the upper main roof and width of the retained entry had the most significant impacts on roof deformation. Bolt and cable support and temporary support in the entry had a non-obvious influence on the roof deformation and could not prevent the given deformation that was caused by the rotation of the upper main roof. Based on comprehensive theoretical analysis and calculation results, ideas and countermeasures to control short cantilever roof deformation-that is, designing a reasonable height of roof cutting and a controlled width of retaining entry-were proposed and tested. Field monitoring shows that the entry control effects were satisfactory.

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“…Combining (12) and (32) with (38), the support working resistance P of a short voussoir is: 2. Case 2: when the breaking of SKS 2 influences that of SKS 1, the influence of SKS 2 should be considered when calculating the support working resistance, and the corresponding support working resistance calculation model is presented in Figure 20B.…”

Section: Determination Of Support Workingmentioning

confidence: 99%

“…The basic mining conditions of their working faces are shown in(38) P H1 = 4i 1 1 − sin max − 3 sin max − 2 cos max 4i 1 + 2i 1 sin max cos max − 2 Q kg max) −3 sin max −2 cos max 4i 1 +2i 1 sin max( cos max −2) The basic mining conditions of their working faces are shown in(38) P H1 = 4i 1 1 − sin max − 3 sin max − 2 cos max 4i 1 + 2i 1 sin max cos max − 2 Q kg max) −3 sin max −2 cos max 4i 1 +2i 1 sin max( cos max −2)…”

mentioning

confidence: 99%

Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height

Zou

2019

Energy Science & Engineering

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The increase in extraction height will increase the mining‐induced overlying strata failure height. In this scenario, the strata pressure behavior is strong in a fully mechanized face with large mining height (FMFLMH), which frequently causes coal wall falls, roof falls, and hydraulic support failure accidents (e.g., support closure and hydraulic column damage). The key to solving these issues is to determine support's working resistance of the FMFLMH. In this paper, comprehensive theoretical analysis, numerical simulation, and field observation were applied to determine the support's working resistance in the FMFLMH based on movement type of the first subordinate key stratum (SKS 1). First, six kinds of movement types of SKS 1 in the FMFLMH are found and defined by theoretical analysis and numerical simulation, which are the direct caving movement type of cantilever structure (direct caving), the double‐sided rotation movement type of cantilever structure (double‐side rotation), the quadratic rotation movement type of cantilever structure (quadratic rotation), the alternative movement type of cantilever structure hinged structure (alternate hinged), the voussoir beam structure movement type (voussoir), and the short voussoir beam structure movement type (short voussoir), respectively. Besides, based on this, the support load calculation model of each movement type was established, and a formula for the support working resistance of each movement type was obtained. Finally, the correctness of the formulae for the support working resistance under six types of movement of SKS 1 were verified using measurement data from four FMFLMHs in China. These research results have important guiding significance for reasonable selection of support and ensuring safe mining of the FMFLMH.

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Numerical Investigation of the Effect of the Location of Critical Rock Block Fracture on Crack Evolution in a Gob-side Filling Wall

Cited by 116 publications

References 29 publications

An Innovative Approach for Gob-Side Entry Retaining in Thick Coal Seam Longwall Mining

An Innovative Approach for Gob-Side Entry Retaining in Thick Coal Seam Longwall Mining

Roof Deformation Characteristics and Preventive Techniques Using a Novel Non-Pillar Mining Method of Gob-Side Entry Retaining by Roof Cutting

Determination of working resistance based on movement type of the first subordinate key stratum in a fully mechanized face with large mining height

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