Numerical Investigation on Roadside Backfill Area Roof Failure Mechanism Subjected to Roadside Backfill Body: A Case Stu
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ORIGINAL PAPER
Numerical Investigation on Roadside Backfill Area Roof Failure Mechanism Subjected to Roadside Backfill Body: A Case Study Zizheng Zhang
. Xianyang Yu
Received: 31 August 2019 / Accepted: 14 May 2020 Ó Springer Nature Switzerland AG 2020
Abstract In retained gob-side entry (RGE) of coal mining, the immediate roof above roadside backfill area (RBA) plays a key part in transferring the main roof load downward and transferring the roadside backfill body (RBB) resistance upon the main roof upward. Numerical investigation was performed to evaluate the stress distribution, deformation characteristics, and plastic zone distribution of the immediate roof above RBA based on a field case of RGE in a Chinese colliery. The double-yield model for gob, strain-softening Mohr–Coulomb model for RBB and strain-softening Mohr–Coulomb model for the roof above RBA were proposed to improve the reliability of the 3D global numerical model in FLAC3D. The numerical results of the calibrated global numerical model indicate that the vertical stress of the immediate roof above RBA shows a V-shaped distribution when the RBB width is less than 2.4 m. The horizontal stress of the immediate roof above RBA reaches the
maximum when the RBB width is 2.0 m. The vertical displacement and horizontal displacement of the immediate roof above RBA positively are associated with the RBB width. In addition, the tensile failure area of the immediate roof above RBA, and the ratio of the tensile failure depth of the immediate roof above RBA to the tensile failure depth of the road-in immediate roof increases with the increase of the RBB width while the tensile failure depth of the immediate roof above RBA decreases. The proposed modeling procedure can be repeated in RGE to evaluate surrounding rock stability with different geological and engineering conditions. Keywords Retained gob-side entry Roadside backfill area Stress distribution Deformation characteristics Plastic zone distribution
1 Introduction Z. Zhang (&) Key Laboratory of Safe and Effective Coal Mining, Ministry of Education (Anhui University of Science and Technology), Huainan 232001, China e-mail: [email protected] Z. Zhang X. Yu Work Safety Key Lab on Prevention and Control of Gas and Roof Disasters for Southern Coal Mines, Hunan Provincial Key Laboratory of Safe Mining Techniques of Coal Mines, Hunan University of Science and Technology, Xiangtan 411201, China
Gob-side entry retaining (GER) with mechanized longwall panel mining is widely employed in China as shown in Fig. 1 (Tan et al. 2015; Yang et al. 2016; Zhang et al. 2017, 2018, 2019a; Tian et al. 2020; Yang et al. 2020). Entry II of longwall panel I is retained as one of gateroads of longwall panel II. When the adjacent longwall panel is mined out, the roadside backfill body (RBB) with various backfill materials is
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Geotech Geol Eng
Fig. 1 Longwall panel layout with RGE
constructed behind of hydraulic support. To achieve GER, the primary objective is
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