Effects of rock weathering on guided wave propagation in rock bolts

Yu, Jung-Doung; Lee, Jong-Sub; Yoon, Ho‐Geun

doi:10.1016/j.tust.2021.104069

Cited by 16 publications

(4 citation statements)

References 55 publications

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“…On-site roof fall accidents occur occasionally. The determination of the range of anchoring action during bolt support and the relationship between the range of reinforcement area formed between adjacent bolts and the spacing between rows of bolts still need to be further studied [23][24][25] .…”

Section: Definition and Theoretical Derivation Of The Bolt Anchorage ...mentioning

confidence: 99%

Study on the anchorage mechanism and roof stability control technology of bolts in fractured or weak surrounding rock

Wang,

Zheng,

Guo

et al. 2024

Preprint

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The effect of bolt support in mining roadways with fractured or weak surrounding rock is poor, and the roof easily loses stability. Studying the support control technology of bolts on fractured surrounding rock is necessary. Based on the theories of pressure arches and combined arch support, the bolt anchorage and anchorage effect angle are proposed a model is established, and the optimal bolt anchorage is calculated. The influence of related factors on the bolt anchorage and the scope of bolt action are analysed via numerical simulation and experimental methods. The pretightening force of the bolts and the spacing between the rows of bolts are positively correlated and negatively correlated with the bolt anchorage, respectively. The compression zone conforms to the reinforced arch state when the bolt end is anchored. The experimental work shows that the maximum spacing a of the anchor rods and the length L of the anchor rods in the surrounding rock satisfy 4.28a < 2L < 5a. The support of fractured surrounding rock is discussed, and the concept of roof fall prevention and control with an increasing or constant pretightening force, high surface strength and reasonable support density as the core principles is proposed. A field test of the Youzhong Coal Mine shows that the corresponding support effect is good and that this work provides a new method for roof support of fractured surrounding rock.

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Section: Definition and Theoretical Derivation Of The Bolt Anchorage ...mentioning

confidence: 99%

Study on the anchorage mechanism and roof stability control technology of bolts in fractured or weak surrounding rock

Wang,

Zheng,

Guo

et al. 2024

Preprint

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“…The lift-off test is generally used to estimate the residual stress of anchors (Saleem and Hosoda. 2021;Yu et al 2021), wherein the anchor head is pulled out using a hydraulic jack; however, this method has limitations in application as it is expensive and time consuming (Vilímek et al 2020). It is impossible to investigate all anchors constructed in the same site, and thus, residual stress is usually only evaluated in a few anchors through sampling tests.…”

Section: Introductionmentioning

confidence: 99%

Application of Infrared Thermography for Estimating Residual Stress in Ground Anchors for Maintenance

Min

Jang

Yoon

2022

Preprint

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Characterizing the integrity of ground anchors is essential for examining their usability in the maintenance of soil structure. However, the lift-off test, which is generally used for this purpose, has limitations when applied to covering all installed ground anchors. The objective of this study is to assess the possibility of using infrared thermography to measure the residual stress in ground anchors as a noncontact technique that bypasses the disadvantages associated with existing techniques. A preliminary experiment is performed to determine the exact emissivity of the tested materials. Both passive and active methods, as representative techniques in infrared thermography, are applied. In the large-scale experiment, infrared images of four installed strands with growing stress in the range of 0-400 kPa at 100 kPa intervals are used in the passive method of measurement. For the active method, these same stress ranges are applied to a heated anchor head using a UTM machine. The results of the passive method show that the temperature increased and decreased according to load and unload steps. Values for the cooling rate index are deduced through the active method results, and reliable behavior are observed at 10 and 15 min. The number of pixels also changed with the loading step in both passive and active methods. This study demonstrates that infrared thermography is a suitable alternative method for assessing the residual stress in ground anchors as a type of noncontact technique.

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“…Guided waves are created by the superposition of longitudinal and transverse waves for a medium in which the diameter is much smaller than the length. Analysis of the pattern of superposition of these waves during propagation of the medium has become a topic of discussion in [23]. The authors there suggest that reading such a pattern can be successfully used to assess the state of the anchoring.…”

Section: Introductionmentioning

confidence: 99%

Non-Destructive Acoustical Rock Bolt Testing System with Intelligent Filtering in Salt Mine ‘Wieliczka’

et al. 2021

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This article presents the application of a self-excited acoustic SAS system for non-destructive testing (NDT) for roof-bolt housings in laboratory and real mine conditions. The proposed system with a filtering mechanism was applied to the J64-27 composite anchors. The conducted tests allowed successful confirmation of the usefulness of the system in the detection of rod defects, damage of the mechanism coupling the anchor to the rock mass and testing of the stress state of the anchor itself. The proposed filtering system allowed eliminating the effect of jump change of frequency in the limit cycle of self-excited system. The proposed method is a novel solution for safety diagnostics of bolt housings in mining applications.

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Effects of rock weathering on guided wave propagation in rock bolts

Cited by 16 publications

References 55 publications

Study on the anchorage mechanism and roof stability control technology of bolts in fractured or weak surrounding rock

Study on the anchorage mechanism and roof stability control technology of bolts in fractured or weak surrounding rock

Application of Infrared Thermography for Estimating Residual Stress in Ground Anchors for Maintenance

Non-Destructive Acoustical Rock Bolt Testing System with Intelligent Filtering in Salt Mine ‘Wieliczka’

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