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Abstract

In order to study the failure mechanism and characteristics for strip coal pillars, a monitoring device for strip coal pillar uniaxial compression testing was developed. Compression tests of simulated strip coal pillars with different roof and floor rock types were conducted. Test results show that, with increasing roof and floor strength, compressive strength and elastic modulus of “roof-strip coal pillar-floor” combined specimens increase gradually. Strip coal pillar sample destruction occurs gradually from edge to the interior. First macroscopic failure occurs at the edge of the middle upper portion of the specimen, and then develops towards the corner. Energy accumulation and release cause discontinuous damage in the heterogeneous coal-mass, and the lateral displacement of strip coal pillar shows step and mutation characters. The brittleness and burst tendency of strip coal pillar under hard surrounding rocks are more obvious, stress growth rate decreases, and the rapid growth acoustic emission (AE) signal period can be regarded as a precursor for instability in the strip coal pillar. The above results have certain theoretical value for understanding the failure law and long-term stability of strip coal pillars.
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Authors and Affiliations

Xiao Qu
1
Shaojie Chen
1
Dawei Yin
Shiqi Liu

  1. Hohai University, China
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Abstract

In the paper there the laboratory tests of interaction between thin-walled beams of the Z crosssection and the sandwich panels with PIR foam core are presented. The different numbers of connectors (0, 4, and 8) were used to connect the sandwich panels with the thin-walled beams. Furthermore, the parallel and perpendicular to the longitudinal axis of the thin-walled beam load arrangement was analysed. The research provides a qualitative and quantitative comparison of the mentioned experiments using the ultimate capacity, the deformation capacity, and the stiffness. In the second part of the paper, the numerical analysis of the thin-walled beam was also performed. The beam was modelled as a shell element and loaded in two ways, which corresponded to the loading scenario during laboratory tests (uniformly distributed and concentrated loads). The results of the numerical calculations of the beam without lateral stabilization were compared with the laboratory results of the beam stabilized by the sandwich panels.
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Authors and Affiliations

Katarzyna Ciesielczyk
1
ORCID: ORCID
Robert Studziński
1
ORCID: ORCID

  1. Poznan University of Technology, Faculty of Civil and Transport Engineering, ul. Piotrowo 3, 60-965 Poznan, Poland
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Abstract

In the article the author discusses peculiarities of three areas of psychologists’ professional activity: conducting scientific research, educating new generations of psychologists, and having a private practice. He particularly stresses the significance of empirical testability of theories for correct and ethical assessment practice (according to Evidence-Based Assessment standard) and therapeutic practice (according to Evidence-Based Practice in Psychology standard). The author also explores the cultural immersion of psychological activity.

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Authors and Affiliations

Jerzy Marian Brzeziński

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