Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress.

Two kinds of common tunnel shapes, i.e. elliptical opening and square opening were selected for biaxial compression tests, and the influences of two kinds of opening shapes on the mechanical properties, failure characteristics and failure modes of sandstone were compared and analyzed. The complex va...

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Main Authors: Honggang Zhao, Haitao Sun, Dongming Zhang, Chao Liu
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2021-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0246815
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author Honggang Zhao
Haitao Sun
Dongming Zhang
Chao Liu
author_facet Honggang Zhao
Haitao Sun
Dongming Zhang
Chao Liu
author_sort Honggang Zhao
collection DOAJ
description Two kinds of common tunnel shapes, i.e. elliptical opening and square opening were selected for biaxial compression tests, and the influences of two kinds of opening shapes on the mechanical properties, failure characteristics and failure modes of sandstone were compared and analyzed. The complex variable theory and mapping functions were used to obtain the analytical stress solution around elliptical and square openings. The results show that the stability of the specimen containing an elliptical opening was better than that of the specimen containing a square opening under the same lateral stress. Compared with the elliptical opening, the local damage was formed earlier in the square opening which might be caused by a higher stress concentration around the square opening. The stress distributions around openings were influenced by the opening shape and lateral stress coefficient. The top and bottom of square opening were more prone to tensile fracture, and the distribution range of tensile was larger than that of elliptical opening. When the opening failed, the intensity of square opening failure was weaker than that of elliptical opening. On the basis of the average frequency value and the rise angle value, the failure mode of specimen containing elliptical or square opening was distinguished. It was found that the mixed tension and shear failure dominated the failure of specimens with different opening shapes, and the number of shear cracks in the specimen containing a square opening was greater than that in the specimen containing an elliptical opening. The above method of judging failure mode by acoustic emission signals was well verified by the CT images of damaged specimens.
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spelling doaj.art-99ac909b18154842881b2b0222b37a752022-12-21T18:29:52ZengPublic Library of Science (PLoS)PLoS ONE1932-62032021-01-01163e024681510.1371/journal.pone.0246815Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress.Honggang ZhaoHaitao SunDongming ZhangChao LiuTwo kinds of common tunnel shapes, i.e. elliptical opening and square opening were selected for biaxial compression tests, and the influences of two kinds of opening shapes on the mechanical properties, failure characteristics and failure modes of sandstone were compared and analyzed. The complex variable theory and mapping functions were used to obtain the analytical stress solution around elliptical and square openings. The results show that the stability of the specimen containing an elliptical opening was better than that of the specimen containing a square opening under the same lateral stress. Compared with the elliptical opening, the local damage was formed earlier in the square opening which might be caused by a higher stress concentration around the square opening. The stress distributions around openings were influenced by the opening shape and lateral stress coefficient. The top and bottom of square opening were more prone to tensile fracture, and the distribution range of tensile was larger than that of elliptical opening. When the opening failed, the intensity of square opening failure was weaker than that of elliptical opening. On the basis of the average frequency value and the rise angle value, the failure mode of specimen containing elliptical or square opening was distinguished. It was found that the mixed tension and shear failure dominated the failure of specimens with different opening shapes, and the number of shear cracks in the specimen containing a square opening was greater than that in the specimen containing an elliptical opening. The above method of judging failure mode by acoustic emission signals was well verified by the CT images of damaged specimens.https://doi.org/10.1371/journal.pone.0246815
spellingShingle Honggang Zhao
Haitao Sun
Dongming Zhang
Chao Liu
Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress.
PLoS ONE
title Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress.
title_full Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress.
title_fullStr Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress.
title_full_unstemmed Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress.
title_short Mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress.
title_sort mechanical properties and progressive failure characteristics of sandstone containing elliptical and square openings subjected to biaxial stress
url https://doi.org/10.1371/journal.pone.0246815
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