为了进一步研究横观各向同性非饱和重塑黄土在复杂应力路径下的变形及强度特性,采用不同试验仪器(非饱和真三轴仪及非饱和三轴仪)对横观各向同性非饱和土体进行了3组共计39个固结剪切试验。结果表明:在真三轴剪切试验中,试样的应力—应变关系曲线呈现出应变硬化特征,并具有双曲线形态,应力也随吸力的增加而提高;随着剪切过程的持续,真三轴试样的含水率不断减小,相同b值、净围压条件下,吸力越大,含水率—轴向应变关系曲线斜率也越大;真三轴试样、K0CD试验试样及K0′CD试验试样在剪切试验中始终呈现剪缩状态;3种不同初始条件下试验试样的破坏应力大小依次为真三轴试验试样最大,K0CD试验试样次之,K0′CD试验试样最小;K0CD试验试样的初始切线模量最大,K0′CD试验试样次之,真三轴试验试样最小。研究成果对于推动横观各向同性非饱和黄土的力学性质研究、完善相关理论和准则、以及指导工程实践具有指导意义。
In order to further investigate the deformation and strength characteristics of transversely isotropic unsaturated remolded loess under complex stress paths, three sets of 39 consolidation shear tests were conducted on transversely isotropic unsaturated soil using different experimental instruments (unsaturated true triaxial apparatus and unsaturated triaxial apparatus). The results show that: In true triaxial shear tests, the stress-strain relationship curve of the specimen exhibits strain hardening characteristics and has a hyperbolic shape, and the stress also increases with the increase of suction force.As the shearing process continues, the moisture content of the true triaxial specimen decreases continuously. Under the same b value and net confining pressure conditions, the greater the suction force, the greater the slope of the moisture content axial strain relationship curve. The true triaxial specimen, K0CD test specimen, and K0′CD test specimen consistently exhibit a state of shear shrinkage during the shear test. The magnitude of the failure stress of the test specimens under three different initial conditions is highest for the true triaxial test specimen, followed by the K0CD test specimen, and lowest for the K0′CD test specimen. The initial tangent modulus of the K0CD test specimen is the highest, followed by the K0′CD test specimen, and the true triaxial test specimen is the smallest. The research results are of great significance for promoting the study of mechanical properties of transversely isotropic unsaturated loess, improving relevant theories and criteria, and guiding engineering practice.
[1] 陈正汉.非饱和土与特殊土力学的基本理论研究[J].岩土工程学报, 2014, 36(2): 201-272.(Chen Zhenghan.On basic theories of unsaturated soils and special soils[J].Chinese Journal of Geotechnical Engineering, 2014, 36(2): 201-272.(in Chinese))
[2] 郭楠, 陈正汉, 杨校辉, 等.横观各向同性非饱和土的增量非线性本构模型及参数变化规律研究[J].岩土工程学报, 2021, 43(12): 2283-2290.(Guo Nan, Chen Zhenghan, Yang Xiaohui, et al.Research on incremental nonlinear constitutive model and parameter variation law of transversely isotropic unsaturated soil[J].Chinese Journal of Geotechnical Engineering, 2021, 43(12): 2283-2290.(in Chinese))
[3] 张坤勇, 殷宗泽, 梅国雄.土体各向异性研究进展[J].岩土力学, 2004(9): 1503-1509.(Zhang Kunyong, Yin Zongze, Mei Guoxiong.Progress in research on soil anisotropy[J].Rock and Soil Mechanics, 2004(9): 1503-1509.(in Chinese))
[4] Li X S,Dafalias Y F.Constitutive modeling of inherently anisotropic sand behavior[J].Journal of Geotechnical and Geoenvironmental Engineering, 2002, 128(10): 868-880.
[5] 路德春, 韩佳月, 梁靖宇, 等.横观各向同性黏土的非正交弹塑性本构模型[J].岩石力学与工程学报, 2020, 39(4): 793-803.(Lu Dechun, Han Jiayue, Liang Jingyu, et al.Non orthogonal elastoplastic constitutive model of transversely isotropic clay[J].Journal of Rock Mechanics and Engineering, 2020, 39(4): 793-803.(in Chinese))
[6] Tobita Y.Fabric tensors in constitutive equations for granular materials[J].Soils and Foundations, 1989, 29(4): 91-104.
[7] 韦雅之, 姚志华, 种小雷, 等.非饱和Q3黄土微细观结构特征及对强度特性影响机制[J].岩土工程学报, 2021, 43(11): 2127-2133.(Wei Yazhi, Yao Zhihua, Zhong Xiaolei, Zhang Jianhua,et al.The microstructural characteristics of unsaturated Q3 loess and its influence mechanism on strength characteristics[J].Journal of Geotechnical Engineering, 2021, 43(11): 2127-2133.(in Chinese))
[8] 张连卫, 张建民, 张嘎.基于SMP的粒状材料各向异性强度准则[J].岩土工程学报, 2008, 30(8): 1107-1111.(Zhang Lianwei, Zhang Jianmin, Zhang Ga.Anisotropic strength criterion for granular materials based on SMP[J].Chinese Journal of Geotechnical Engineering, 2008, 30(8): 1107-1111.(in Chinese))
[9] Matsuoka H, Nakai T, Ishizaki H.A stress-strain relationship for anisotropic soils based on spatial mobilized plane[J].Proceedings of the Japan Society of Civil Engineers, 1980, 304: 105-111.
[10] Lade P V,Abelev A V.Characterization of cross-anisotropic soil deposits from isotropic compression tests[J].Soils and Foundations, 2005, 45(5): 89-102.
[11] Abelev A V, Lade P V.Characterization of failure in cross-anisotropic soils[J].Journal of Engineering Mechanics, 2004, 130(5): 599-606.
[12] 姚仰平, 孔玉侠.横观各向异性土强度与破坏准则的研究[J].水利学报, 2012, 43(1): 1107-1111.(Yao Yangping, Kong Yuxia.Study on strength failure criterion of cross-anisotropic soil[J].Journal of Hydraulic Engineering, 2012, 43(1): 1107-1111.(in Chinese))
[13] 万征, 宋琛琛, 赵晓光.一种横观各向同性强度准则及变换应力空间[J].力学学报, 2018, 50(5): 1168-1184.(Wan Zheng, Song Chenchen, Zhao Xiaoguang.A transverse isotropic strength criterion and transformed stress space[J].Chinese Journal of Theoretical and Applied Mechanics, 2018, 50(5): 1168-1184.(in Chinese))
[14] 郭楠.非饱和土的增量非线性横观各向同性本构模型研究[D].兰州:兰州理工大学, 2018.(Guo Nan.Study on incremental nonlinear transverse isotropic constitutive model of unsaturated soil[D].Lanzhou: Lanzhou University of Technology, 2018.(in Chinese))
[15] 郭楠, 陈正汉, 杨校辉, 等.各向同性土与横观各向同性土的力学特性和持水特性[J].西南交通大学学报, 2019, 54(6): 1235-1243.(Guo Nan, Chen Zhenghan, Yang Xiaohui, et al.Mechanical and water holding properties of isotropic soil and transversely isotropic soil[J].Journal of Southwest Jiaotong University, 2019, 54(6): 1235-1243.(in Chinese))
[16] 张敏, 许成顺, 杜修力, 等.中主应力系数及应力路径对砂土剪切特性影响的真三轴试验研究[J].水利学报, 2015, 46(9): 1072-1079.(Zhang Min, Xu Chengshun, Du Xiuli, et al.A true triaxial experimental study on the effects of middle principal stress coefficient and stress path on the shear characteristics of sandy soil[J].Journal of Hydraulic Engineering, 2015, 46(9): 1072-1079.(in Chinese))
[17] 左永振, 姜景山, 潘家军, 等.粗粒料变形特性的大型真三轴试验研究[J].岩土工程学报, 2019, 41(增2): 37-40.(Zuo Yongzhen, Jiang Jingshan, Pan Jiajun, et al.Large scale true triaxial experimental study on deformation characteristics of coarse grained materials[J].Chinese Journal of Geotechnical Engineering, 2019, 41(Supp.2): 37-40.(in Chinese))
[18] 许萍, 邵生俊, 张帅.黄土(Q3)横观各向同性强度准则研究[J].岩土工程学报, 2018, 40(1): 116-121.(Xu Ping, Shao Shengjun, Zhang Shuai.Research on the transverse isotropic strength criterion of loess (Q3)[J].Chinese Journal of Geotechnical Engineering, 2018, 40(1): 116-121.(in Chinese))
[19] 代金秋, 苏仲杰, 赵明超, 等.粉质黏土的真三轴试验及强度特性研究[J].岩土力学, 2016, 37(9): 2534-2540, 2546.(Dai Jinqiu, Su Zhongjie, Zhao Mingchao, et al.Study on true triaxial testing and strength characteristics of silty clay[J].Rock and Soil Mechanics, 2016, 37(9): 2534-2540, 2546.(in Chinese))
[20] 陈正汉.非饱和土试验方法标准[M].北京: 中国建筑工业出版社, 2023.(Chen Zhenghan.Standard test method for unsaturated soil[M].Beijing: China Architecture and Building Press, 2023.(in Chinese))
[21] 陈正汉.重塑非饱和黄土的变形、强度、屈服和水量变化特性[J].岩土工程学报, 1999, 21(1): 82-90.(Chen Zhenghan.Deformation, strength, yield and moisture change of a remolded unsaturated loess[J].Chinese Journal of Geotechnical Engineering, 1999, 21(1): 82-90.(in Chinese))
[22] Duncan J M, Chang C Y.Nonlinear analysis of stress and strain in soils[J].Journal of the Soil Mechanics and Foundation Division, ASCE, 1970, 96(5): 1629-1653.
