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郭楠, 陈正汉, 杨校辉, 高登辉. 横观各向同性非饱和黄土的真三轴试验研究[J]. 岩土工程学报, 2022, 44(S1): 74-79. DOI: 10.11779/CJGE2022S1014
引用本文: 郭楠, 陈正汉, 杨校辉, 高登辉. 横观各向同性非饱和黄土的真三轴试验研究[J]. 岩土工程学报, 2022, 44(S1): 74-79. DOI: 10.11779/CJGE2022S1014
GUO Nan, CHEN Zheng-han, YANG Xiao-hui, GAO Deng-hui. True triaxial tests on transversely isotropic unsaturated loess[J]. Chinese Journal of Geotechnical Engineering, 2022, 44(S1): 74-79. DOI: 10.11779/CJGE2022S1014
Citation: GUO Nan, CHEN Zheng-han, YANG Xiao-hui, GAO Deng-hui. True triaxial tests on transversely isotropic unsaturated loess[J]. Chinese Journal of Geotechnical Engineering, 2022, 44(S1): 74-79. DOI: 10.11779/CJGE2022S1014

横观各向同性非饱和黄土的真三轴试验研究

True triaxial tests on transversely isotropic unsaturated loess

  • 摘要: 为了研究复杂应力路径下横观各向同性非饱和黄土的力学特性,采用真三轴仪对横观各向同性非饱和重塑黄土进行了两组共15个剪切试验。第一组9个试验,每个试验包括两个阶段,即试样先在竖向压力为常数的条件下进行K0预固结,再进行控制吸力、净围压和中主应力参数b为常数的真三轴固结排水剪切试验;第二组6个试验,为不同剪切速率下,控制吸力、净围压和中主应力参数b为常数的真三轴固结不排水剪切试验。试验结果表明:真三轴固结排水剪切试验中各应力–应变曲线皆为硬化型,且满足双曲线形式,b值越大试样的硬化趋势越明显;所有的试样在剪切过程中均处于剪缩状态,随着剪切的发展试样的含水率不断减小,试样破坏前含水率–轴向应变关系可近似为直线。真三轴固结不排水剪切试验中,加载速率对应力–应变曲线的基本形态并没有多大影响,但是对试样的刚度有一定影响,该影响效应也不是单调的,有可能存在临界速率;试样在剪切过程中体积不断缩小,饱和度随着偏应力的增大而增大,故孔隙水压力增大,吸力不断减小。本文的研究成果可为横观各向同性非饱和黄土的本构模型及强度准则的建立及工程应用提供有益的参考。

     

    Abstract: In order to study the mechanical properties of transversely isotropic unsaturated remolded loess under complex stress paths, two groups of 15 tests are carried out using the true triaxial apparatus. The first group consists of 9 tests, each of which includes two stages: the sample is pre-consolidated by K0 under the constant vertical pressure, and then the true triaxial consolidated drained shear tests with the constant suction, net confining pressure and intermediate principal stress parameter are carried out. The second group of 6 tests are the true triaxial shear ones with the constant water content under different shear rates and the constant suction, net confining pressure and intermedium principal stress parameter. The test results show that all the stress-strain curves in the true triaxial consolidated drained shear tests are hardening type and in hyperbolic form, and the hardening trend is more obvious with the increase of the intermedium principal stress parameter. All the samples are in shear contraction state during the shearing process, and the water content of the samples decreases with the shearing process. The water content-axial strain relationship curve of the samples before failure can be approximated as a straight line. In the true triaxial shear tests with the constant water content, the loading rate has few effects on the basic form of the stress-strain curve, but has certain effects on the stiffness of the samples, which are not monotonous, so there may be a critical rate. In the shear process, the volume of the samples decreases continuously, and the saturation increases with the increase of the deviatoric stress, so the pore water pressure increases and the suction decreases continuously. The research results may provide useful reference for the establishment of constitutive model and strength criterion for the transversely isotropic unsaturated loess and its engineering application.

     

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