Experimental research on the electromagnetic radiation (EMR) characteristics of cracked rock.

Environmental science and pollution research international · 2018 · Unclear · Low evidence

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UnclearLow evidencePaper 6643

Study snapshot

PublicationEnvironmental science and pollution research international · 2018

Study typeother

Reported directionUnclear

Evidence ratingLow

Abstract

Coal rock would emit the electromagnetic radiation (EMR) while deformation and fracture, and there exists structural body in the coal rock because of mining and geological structure. In this paper, we conducted an experimental test the EMR characteristics of cracked rock under loading. Results show that crack appears firstly in the prefabricated crack tip then grows stably parallel to the maximum principal stress, and the coal rock buckling failure is caused by the wing crack tension. Besides, the compressive strength significantly decreases because of the precrack, and the compressive strength increases with the crack angle. Intact rock EMR increases with the loading, and the cracked rock EMR shows stage and fluctuant characteristics. The bigger the angle, the more obvious the stage and fluctuant characteristics, that is EMR becomes richer. While the cracked angle is little, EMR is mainly caused by the electric charge rapid separates because of friction sliding. While the cracked angle is big, there is another significant contribution to EMR, which is caused by the electric dipole transient of crack expansion. Through this, we can know more clear about the crack extends route and the corresponding influence on the EMR characteristic and mechanism, which has important theoretical and practical significance to monitor the coal rock dynamical disasters.

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Study typeother

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

In loading tests, cracks initiated at the prefabricated crack tip and grew stably parallel to the maximum principal stress; buckling failure was attributed to wing crack tension. Precracks significantly reduced compressive strength, and compressive strength increased with crack angle. EMR from intact rock increased with loading, while cracked rock EMR showed staged and fluctuating characteristics that became more pronounced with larger crack angles; proposed contributors included frictional sliding (small crack angle) and transient electric dipoles during crack expansion (large crack angle).

Outcomes measured

Electromagnetic radiation (EMR) characteristics during loading/deformation and fracture of cracked coal rock
Crack initiation/propagation behavior under loading
Compressive strength changes with precrack presence and crack angle

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": null,
    "source": "other",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Electromagnetic radiation (EMR) characteristics during loading/deformation and fracture of cracked coal rock",
    "Crack initiation/propagation behavior under loading",
    "Compressive strength changes with precrack presence and crack angle"
  ],
  "main_findings": "In loading tests, cracks initiated at the prefabricated crack tip and grew stably parallel to the maximum principal stress; buckling failure was attributed to wing crack tension. Precracks significantly reduced compressive strength, and compressive strength increased with crack angle. EMR from intact rock increased with loading, while cracked rock EMR showed staged and fluctuating characteristics that became more pronounced with larger crack angles; proposed contributors included frictional sliding (small crack angle) and transient electric dipoles during crack expansion (large crack angle).",
  "effect_direction": "unclear",
  "limitations": [],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "electromagnetic radiation",
    "EMR",
    "coal rock",
    "cracked rock",
    "loading test",
    "fracture",
    "crack angle",
    "compressive strength",
    "wing crack",
    "friction sliding",
    "electric dipole transient",
    "mining"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1007/s11356-017-1012-0
PubMed: 29255984

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