Study on Coal Pillar Size Design Based on Non-integral Contact Structure of Coal and Rock Under Static and Dynamic Loads

Li, Jingkai; Wang, Zhiqiang; Li, Kaixin; Zhang, Cunzhi

doi:10.3389/fmats.2021.721713

Cited by 4 publications

(1 citation statement)

References 33 publications

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“…The determination of pillar sizes is made by studying the pillar load and pillar strength. The goal of pillar design is to give the left pillars sufficient strength to carry the pillar loads [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Fracture Process and Failure Characteristics of Sandstone with Different Height-to-Diameter Ratios

Zhang,

Li,

Yan

et al. 2023

Processes

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The mechanical properties of rock materials significantly depend on their size due to their heterogeneity and the spatial randomness of joint development—a factor often neglected in pillar design and stability analyses within mining engineering. The rock samples examined herein were 100 mm in diameter and 100 mm, 200 mm, or 300 mm in height. This research analyzed the respective mechanical phenomena and failure patterns of rock specimens with varying height-to-diameter ratios under uniaxial compression. The experiment showed that the greater the height-to-diameter ratio, the smaller the elastic modulus and compressive strength. Remarkably, as the height-to-diameter ratio grew, the failure forms of the samples transitioned from splitting to shearing, while their peak strength gradually diminished. Specifically, a hike from 1:1 to 3:1 in the height-to-diameter ratio led to a roughly 20% decrease in peak strength. Utilizing the real rock fracture process analysis system (RFPA3D), the fracture processes and failure characteristics of rock specimens with dissimilar aspect ratios were comparatively explored from a microscopic viewpoint, with acoustic emissions revealing the entire process from crack initialization to penetration. The failure analysis affirmed that the simulation results corresponded closely with the experimental findings. The resultant research can offer theoretical support for the multiscale mechanical properties, fracture processes, and prediction of rock failure in mining engineering.

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Section: Introductionmentioning

confidence: 99%

Fracture Process and Failure Characteristics of Sandstone with Different Height-to-Diameter Ratios

Zhang,

Li,

Yan

et al. 2023

Processes

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Key Bearing Structure Instability Mechanism: A Case Study in Mining Under Close‐Distance Coal Pillar

Ma,

Tu,

et al. 2024

Geofluids

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This study is aimed at solving the issue of mining under the boundary coal pillar of the close‐distance coal seam that causes roof falling. This study established a new key bearing structure model for analyzing the structural instability mechanism when mining under the coal pillar at the working face by taking Shaping Coal Mine as an example. The purpose of this study is to analyze the formation process, load transfer mechanism, and two failure types of the key bearing structure using theoretical analysis and numerical simulation. Additionally, this study discussed the timing and method of roof control for different key bearing structure failure types. Research shows that the instability of the key bearing structure composed of the coal pillar, interlayer rock, and lower coal body is the important reason behind the roof falling. The instability types of key bearing structures include the coal pillar instability type and the cantilever beam instability type. The stability width of the interlayer rock cantilever beam and the coal pillar jointly ascertain the failure type of the key bearing structure. In the 9204 working face, the key bearing structure was destroyed when the coal pillar was 14 m wide, resulting in the roof stress being as high as 31.81 MPa. The stress drop phenomenon can be used as a boundary to divide the failure process of the key bearing structure into three stages. The pressure relief of the coal pillar and interlayer rock cantilever beam is an effective way to deal with this problem, and the coal pillar instability type needs to be pressure relieved earlier than the cantilever beam instability type. The research findings offer new insights into the roof stability control of mining under the coal pillar.

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Mechanical Properties of Rock–Coal–Rock Composites at Different Inclined Coal Seam Thicknesses

Wang

et al. 2022

Front. Phys.

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A comprehensive understanding of the mechanical properties of coal and rock sections is necessary for interpreting the deformation and failure modes of such underground sections and for evaluating the potential dynamic hazards. However, most studies have focused on horizontal coal–rock composites and the mechanical properties of inclined coal–rock composites have not been considered. To explore the influence of different confining pressures and inclined coal seam thicknesses on the mechanical properties and failure characteristics of rock–coal–rock (RCR) composites, a numerical model based on the particle flow code was used to perform simulations on five inclined RCR composites at different confining pressures. The results show that the mechanical properties and failure characteristics of the RCR composites are affected considerably by the inclined coal seam thickness and the confining pressure. (1) When the inclined coal seam thickness is constant, the elasticity modulus of the inclined RCR composite increases nonlinearly with the confining pressure at first, and then remains constant. At the same confining pressure, the elasticity modulus of the inclined RCR composite decreases nonlinearly with the inclined coal seam thickness. (2) When the confining pressure is constant, the peak stress of the inclined RCR composite decreases with the increase of the inclined coal seam thickness. When the inclined coal seam thickness is constant, the peak stress increases with the confining pressure. (3) As the inclined coal seam thickness increases, the peak strain of the inclined RCR composite first decreases rapidly, and then remains constant when there is no confining pressure. When the confining pressure is between 5 and 20 MPa, the peak strain of the inclined RCR composite gradually increases. (4) In the absence of confining pressure, there are few microcracks in the rock at an inclined coal seam thickness of 10 mm, whereas all the other cracks are in the coal section. When the confining pressure ranges between 5 and 20 MPa, the failure modes of the RCR composite can be divided into Y- and X-types.

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Study on Coal Pillar Size Design Based on Non-integral Contact Structure of Coal and Rock Under Static and Dynamic Loads

Cited by 4 publications

References 33 publications

Fracture Process and Failure Characteristics of Sandstone with Different Height-to-Diameter Ratios

Fracture Process and Failure Characteristics of Sandstone with Different Height-to-Diameter Ratios

Key Bearing Structure Instability Mechanism: A Case Study in Mining Under Close‐Distance Coal Pillar

Mechanical Properties of Rock–Coal–Rock Composites at Different Inclined Coal Seam Thicknesses

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