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[an error occurred while processing this directive]Study on the Softening Model and Strength of Red Clay at Different Water Content
Received date: 2019-07-10
Revised date: 2020-03-12
Online published: 2020-07-01
In engineering geology,red clay especially refers to the high plastic clay,which color is brownish-red or brown-yellow and so on,formed by lateralization of exposed rocks of the carbonate system.The red clay sample in this study was taken from 20 m underground in Changzhi area of Shanxi Province,China,which is a special red clay with high pores,high shrinkage and strong hydrophilic properties.The basic physical parameters of red clay were first measured according to the standard for geotechnical test methods(GB/T50123-1999),besides,the mineral composition of the red clay was appraised by X diffraction analysis.The results show that the content of the I/S layer in the red clay is high.In order to study the softening characteristics of the remodeling of red clay and the relationship between shear strength and moisture content,undrained triaxial tests was carried out using the TSZ-2 automatic strain control three-axis instrument.A total of 24 cylindrical specimens were produced during the experiment,each cylindrical sample size is 39.1 mm×80 mm.Because the moisture content of the original soil is about 17.0% to 23.7%,so the moisture content of remodel red clay is 15%,18%,21%,24% respectively.And confining pressures of 100 kPa,200 kPa and 300 kPa were applied respectively at each moisture content.The relationship between moisture content, principal stress difference,cohesion and internal friction angle was obtained from the experiment.When the moisture content changes, the remold red clay of Changzhi area of Shanxi Province have different failure forms.It would have macroscopic shear failure under low moisture content and confining pressure,meanwhile,the stress-strain curve has obviously softening phenomenon, and the modified stress-strain softening model can be better to simulate the test curve.Due to the high mineral content of I/S layer of the remolded red clay in Changzhi area,Shanxi Province,China,so the red clay has a large pore inside,with the increase of moisture content and confining pressure,the specimen from macro-shear damage to plastic damage,besides,when the moisture content is 15% to 24%,there is a linear relationship between the non-draining anti-shear strength and moisture content of this kind of red clay.The research results in this paper can provide reference for the related foundation treatment in the special red clay area of Changzhi,Shanxi Province,China,and also provide a theoretical basis for the further mathematical model of special red clay.
Huaixin LI , Bin LIN , Shiwei CHEN , Peng WANG . Study on the Softening Model and Strength of Red Clay at Different Water Content[J]. Gold Science and Technology, 2020 , 28(3) : 442 -449 . DOI: 10.11872/j.issn.1005-2518.2020.03.130
http://www.goldsci.ac.cn/article/2020/1005-2518/1005-2518-2020-28-3-442.shtml
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