Spontaneous caving and gob-side entry retaining of thin seam with large inclined angle

Zhang, Yongqin; Jianxin, Tang; Xiao, Daqiang; Sun, Lele; Zhang, Weizhong

doi:10.1016/j.ijmst.2014.05.004

Cited by 26 publications

(19 citation statements)

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“…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%

“…(a) Deformation characteristics of roof strata Deng and Wang (2014) and Zhang et al (2014) [5,6] analyzed roof deformation, failure laws, and roadway support technology of gob-side entry retaining in a thin seam with a large inclined angle. Li et al (2015), Wang et al (2001), Gao et al (2000), and Lu et al (2011) [7][8][9][10] established a mechanical model related to the immediate roof of the entry using elastoplastic mechanics theory and obtained deformation characteristics under the effects of a given deformation of the upper main roof.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

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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“…Traditional roadside support can be achieved with many techniques [9,[17][18][19], including the wood stack, waste rock pillar, dense hydraulic props, concrete blocks and other artificial product supports of low intensity. The supporting resistance and deformability of traditional roadside support cannot adapt for the deformation of surrounding rock and is unable to isolate gob effectively, making it difficult to achieve high mechanization.…”

Section: Mechanical Model For Ger-tcs-lrmentioning

confidence: 99%

Key Parameters of Gob-Side Entry Retaining in A Gassy and Thin Coal Seam with Hard Roof

et al. 2018

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Gob-side entry retaining (GER) employed in a thin coal seam (TCS) can increase economic benefits and coal recovery, as well as mitigate gas concentration in the gob. In accordance with the caving style of a limestone roof, the gas concentration and air pressure in the gob were analyzed, and a roof-cutting mechanical model of GER with a roadside backfill body (RBB) was proposed, to determine the key parameters of the GER-TCS, including the roof-cutting resistance and the width of the RBB. The results show that if the immediate roof height is greater than the seam height, the roof-cutting resistance and width of the RBB should meet the requirement of the immediate roof being totally cut along the gob, for which the optimal roof-cutting resistance and width of RBB were determined by analytical and numerical methods. The greater the RBB width, the greater its roof-cutting resistance. The relationship between the supporting strength of the RBB and the width of the RBB can be derived as a composite curve. The floor heave of GER increases with increasing RBB width. When the width of the RBB increased from 0.8 m to 1.2 m, the floor heave increased two-fold to 146.2 mm. GER was applied in a TCS with a limestone roof of 5 m thickness; the field-measured data verified the conclusions of the numerical model.

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“…Reducing the entry-retaining cost and improving the entry-retaining speed have long been crucial issues that need to be further and continuously addressed by engineers and researchers. Hence, many different types of artificial walls have been developed, such as gangue walls, concrete-filled walls, high water-content material filled walls, concrete-block walls, and so on [13][14][15][16]. Among them, the concrete-block wall, as shown in Figure 1, has been widely used and has achieved good results because of its low cost and strong adaptability.…”

Section: Introductionmentioning

confidence: 99%

Development of a New Gob-Side Entry-Retaining Approach and Its Application

et al. 2018

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Gob-side entry retaining plays an important role in the sustainable exploitation of coal resources and has been widely used in coal mining. However; some disadvantages, such as high labour intensity and low efficiency of wall construction, have gravely restricted the application of this technique. To solve this issue, this paper developed a new gob-side entry retaining approach including a lightweight and high-strength foam concrete and a mortise-and-tenon structure hollow-block wall. The experiment results show that the preparation of foam concrete with a density of 1200 kg/m 3 ; with uniaxial compressive strength greater than 15 MPa, can be realized by the chemical-foaming method. The method is performed by adding silica fume, slag and fly ash to a system of "cement and sand" structure collocation and by optimizing the proportioning of the materials. The density of foam concrete is reduced by 50% relative to that of common concrete which can greatly reduce the weight of the blocks. Compared with the conventional gob-side entry-retaining wall the new wall structure has many advantages. For example, it can improve stability by increasing the width-to-height ratio of the wall and save 44.44% of the material, and at the same time; it can save manpower and improve labour efficiency. Finally, the new approach was tested in the 3203 gob-side entry-retaining working face in a Chinese coal mine and the application effect proves that the new approach is well suited for entry retaining. The wall structure and parameters are reasonable. This work can contribute to the sustainable and efficient exploitation of underground coal resources.

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Spontaneous caving and gob-side entry retaining of thin seam with large inclined angle

Cited by 26 publications

References 0 publications

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

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

Key Parameters of Gob-Side Entry Retaining in A Gassy and Thin Coal Seam with Hard Roof

Development of a New Gob-Side Entry-Retaining Approach and Its Application

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