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Study on Strength Characteristics and Microstructure of Completely Decomposed Migmatitic Granite
https://orcid.org/http://orcid.org/0000-0002-9004-6955
https://orcid.org/http://orcid.org/0000-0002-9175-7257
https://orcid.org/http://orcid.org/0000-0003-2153-4645
Migmatitic granite is the product of mixed lithification and granitization, and completely decomposed migmatitic granite (CDMG) was formed after weathering. The engineering properties of CDMG are complex, and its engineering properties are complex after weathering, and water content has a great influence on the properties of (CDMG). Due to its loose structure and strong heterogeneity, it is difficult to determine its strength characteristics by conventional test methods. In the paper triaxial and micro-CT test were conducted to study the relationship between shear strength and microstructure of CDMG under different water content. The results show that with the increase of water content from 6% to 14%, the internal friction angle decreases from 31.8° to 27.3°, and the cohesion first increases from 76.5 kPa to 94.3 kPa and then decreases to 77.7 kPa. This is because the sliding friction coefficient between coarse particles decreases with the increase of water film thickness on the surface of particles, and the occlusal effect between coarse particles weakens and the displacement adjustment is easier during the triaxial loading process. Under different water content, the shear strength of CDMG is not sensitive to particle structure parameters including particle size, particle morphology and particle arrangement. The particle analysis results of post-test sample show that the crushing proportion of coarse particles increases with the increase of the internal friction angle. The clay minerals produce differential expansion potential with the increase of water content, and the porosity and pore connectivity first decrease and then increase. Cohesion has a linear relationship with porosity and pore connectivity. With the increase of porosity from 23.95% to 26.95%, cohesion decreases linearly by 17%. These results indicate that the internal friction angle of CDMG can be inferred by water content, and the cohesion can be inferred by porosity and pore connectivity obtained by microstructure analysis.
Study on Strength Characteristics and Microstructure of Completely Decomposed Migmatitic Granite
https://orcid.org/http://orcid.org/0000-0002-9004-6955
https://orcid.org/http://orcid.org/0000-0002-9175-7257
https://orcid.org/http://orcid.org/0000-0003-2153-4645
Migmatitic granite is the product of mixed lithification and granitization, and completely decomposed migmatitic granite (CDMG) was formed after weathering. The engineering properties of CDMG are complex, and its engineering properties are complex after weathering, and water content has a great influence on the properties of (CDMG). Due to its loose structure and strong heterogeneity, it is difficult to determine its strength characteristics by conventional test methods. In the paper triaxial and micro-CT test were conducted to study the relationship between shear strength and microstructure of CDMG under different water content. The results show that with the increase of water content from 6% to 14%, the internal friction angle decreases from 31.8° to 27.3°, and the cohesion first increases from 76.5 kPa to 94.3 kPa and then decreases to 77.7 kPa. This is because the sliding friction coefficient between coarse particles decreases with the increase of water film thickness on the surface of particles, and the occlusal effect between coarse particles weakens and the displacement adjustment is easier during the triaxial loading process. Under different water content, the shear strength of CDMG is not sensitive to particle structure parameters including particle size, particle morphology and particle arrangement. The particle analysis results of post-test sample show that the crushing proportion of coarse particles increases with the increase of the internal friction angle. The clay minerals produce differential expansion potential with the increase of water content, and the porosity and pore connectivity first decrease and then increase. Cohesion has a linear relationship with porosity and pore connectivity. With the increase of porosity from 23.95% to 26.95%, cohesion decreases linearly by 17%. These results indicate that the internal friction angle of CDMG can be inferred by water content, and the cohesion can be inferred by porosity and pore connectivity obtained by microstructure analysis.
Study on Strength Characteristics and Microstructure of Completely Decomposed Migmatitic Granite
https://orcid.org/http://orcid.org/0000-0002-9004-6955
https://orcid.org/http://orcid.org/0000-0002-9175-7257
https://orcid.org/http://orcid.org/0000-0003-2153-4645
Migmatitic granite is the product of mixed lithification and granitization, and completely decomposed migmatitic granite (CDMG) was formed after weathering. The engineering properties of CDMG are complex, and its engineering properties are complex after weathering, and water content has a great influence on the properties of (CDMG). Due to its loose structure and strong heterogeneity, it is difficult to determine its strength characteristics by conventional test methods. In the paper triaxial and micro-CT test were conducted to study the relationship between shear strength and microstructure of CDMG under different water content. The results show that with the increase of water content from 6% to 14%, the internal friction angle decreases from 31.8° to 27.3°, and the cohesion first increases from 76.5 kPa to 94.3 kPa and then decreases to 77.7 kPa. This is because the sliding friction coefficient between coarse particles decreases with the increase of water film thickness on the surface of particles, and the occlusal effect between coarse particles weakens and the displacement adjustment is easier during the triaxial loading process. Under different water content, the shear strength of CDMG is not sensitive to particle structure parameters including particle size, particle morphology and particle arrangement. The particle analysis results of post-test sample show that the crushing proportion of coarse particles increases with the increase of the internal friction angle. The clay minerals produce differential expansion potential with the increase of water content, and the porosity and pore connectivity first decrease and then increase. Cohesion has a linear relationship with porosity and pore connectivity. With the increase of porosity from 23.95% to 26.95%, cohesion decreases linearly by 17%. These results indicate that the internal friction angle of CDMG can be inferred by water content, and the cohesion can be inferred by porosity and pore connectivity obtained by microstructure analysis.
Study on Strength Characteristics and Microstructure of Completely Decomposed Migmatitic Granite
KSCE J Civ Eng
Yan, Song (author) / Tang, Hua (author) / Wu, Zhenjun (author) / Li, Sitao (author) / Li, Peifeng (author)
KSCE Journal of Civil Engineering ; 27 ; 80-97
2023-01-01
18 pages
Article (Journal)
Electronic Resource
English
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