Computers and Concrete

  • 제32권5호
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  • Pages.465-474
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  • 2023
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  • 1598-8198(pISSN)
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  • 1598-818X(eISSN)
테크노프레스 (Techno-Press)
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DOI QR코드

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A self-confined compression model of point load test and corresponding numerical and experimental validation

  • Qingwen Shi (School of Mine Safety, North China Institute of Science and Technology) ;
  • Zhenhua Ouyang (School of Mine Safety, North China Institute of Science and Technology) ;
  • Brijes Mishra (Department of Mining Engineering, The University of Utah) ;
  • Yun Zhao (Department of Mineral Resources, Xingfa Group)
  • 투고 : 2021.12.02
  • 심사 : 2023.06.20
  • 발행 : 2023.11.25
⟨ 이전 논문 다음 논문 ⟩

초록

The point load test (PLT) is a widely-used alternative method in the field to determine the uniaxial compressive strength due to its simple testing machine and procedure. The point load test index can estimate the uniaxial compressive strength through conversion factors based on the rock types. However, the mechanism correlating these two parameters and the influence of the mechanical properties on PLT results are still not well understood. This study proposed a theoretical model to understand the mechanism of PLT serving as an alternative to the UCS test based on laboratory observation and literature survey. This model found that the point load test is a self-confined compression test. There is a compressive ellipsoid near the loading axis, whose dilation forms a tensile ring that provides confinement on this ellipsoid. The peak load of a point load test is linearly positive correlated to the tensile strength and negatively correlated to the Poisson ratio. The model was then verified using numerical and experimental approaches. In numerical verification, the PLT discs were simulated using flat-joint BPM of PFC3D to model the force distribution, crack propagation and BPM properties' effect with calibrated micro-parameters from laboratory UCS test and point load test of Berea sandstones. It further verified the mechanism experimentally by conducting a uniaxial compressive test, Brazilian test, and point load test on four different rocks. The findings from this study can explain the mechanism and improve the understanding of point load in determining uniaxial compressive strength.

키워드

과제정보

The research described in this paper was financially supported by the National Nature Science Foundation of China [Grant No.52274120].

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