True triaxial tests on influence of spherical and deviatoric stresses on deformation of coarse-grained soil
SHI Wei-cheng1, 2, ZHU Jun-gao3, DAI Guo-zhong1, LU Xi4
1. Changzhou Key Lab of Construction Engineering Structure and Material Properties, Changzhou Institute of Technology, Changzhou 213002, China; 2. Key Laboratory of Hydraulic and Waterway Engineering of Chinese Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China; 3. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098, China; 4. School of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001, China
Abstract:In order to study the influence of p, q and θσ on the deformation of coarse-grained soil, several tests in which only one of the three variables changes while the other two keep constant are performed on coarse-grained soil by using the TSW-40 type true triaxial apparatus in Hohai University. The results show that if p decreases with constant q and b, few deviatoric strain but some volumetric dilation will be generated at the preliminary stage. With the decrease of p, the volumetic dilation increases, which causes the increase of deviatoric strain that is smaller than the volumetric strain in absolute value. Later both the volumetric strain and the deviatoric strain will be accelerated until failure. It indicates that the decrease of p induces the volumetric dilation immediately, which loosens the particle structure, and then the deviatoric strain will be generated. If q increases with constant p and b, little volumetric dilation but some deviatoric strain will be produced at the preliminary stage. With the increase of q, the deviatoric strain increases, which causes the increase of the volumetric dilation that is smaller than the deviatoric strain in absolute value. Later both the deviatoric strain and the volumetric strain will be accelerated until failure. It demonstrates that the increase of q induces the deviatoric strain directly which causes particle dislocation, and then the volumetric dilation will be produced. If θσ changes with constant p and q, some but very small unrecoverable volumetric and deviatoric strains will be generated. Two parameters sp (sp =(p/q-p0/q0)/(1/Mf-p0/q0)) and sq (sp=(q/p-q0/p0)/(Mf-q0/p0)) are introduced, in which p0 and q0 are the initial spheric stress and the deviatoric stress respectively, Mf is the stress ratio at failure. The test results show that when p decreases with constant q and b, dεv/dp and 1/(1-sp)1/2-1 are in direct proportion; dεs/dp and -sp[1/(1-sp)1/2-1] are in direct proportion; stress-dilatancy equation is dεv/dεs= -1/sp. When q increases with constant p and b, dεs/dq and 1/(1-sq)1/2-1 are in direct proportion; dεv/dq and -sq[1/(1-sq)1/2-1] are in direct proportion; stress-dilatancy equation is dεv/dεs= -sq. Finally the characteristics of the flexibility matrix of coarse-grained soil are analyzed according to the test results.
施维成, 朱俊高, 代国忠, 卢曦. 球应力和偏应力对粗粒土变形影响的真三轴试验研究[J]. 岩土工程学报, 2015, 37(5): 776-783.
SHI Wei-cheng, ZHU Jun-gao, DAI Guo-zhong, LU Xi. True triaxial tests on influence of spherical and deviatoric stresses on deformation of coarse-grained soil. Chinese J. Geot. Eng., 2015, 37(5): 776-783.
[1] ROWE P W. The stress-dilatancy relation for static equilibrium of an assembly of particles in contact[C]// Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences, 1962: 500-527. doi:10.1098/rspa. 1962.0193. [2] 张丙印, 贾延安, 张宗亮. 堆石体修正Rowe剪胀方程与南水模型[J]. 岩土工程学报, 2007, 29(10): 1443-1448. (ZHANG Bing-yin, JIA Yan-an, ZHANG Zong-liang. Modified Rowe's dilatancy law of rockfill and SHEN Zhujiang's double yield surfaces elastoplastic model[J]. Chinese Journal of Geotechnical Engineering, 2007, 29(10): 1443-1448. (in Chinese)) [3] LO S-C R, LEE I K. Response of granular soil along constant stress increment ratio path[J]. Journal of Geotechnical Engineering, 1990, 116(3): 355-376. [4] 张荣堂, 陈守义. 减 p 路径下饱和软黏土应力应变性状的试验研究[J]. 岩土力学, 2002, 23(5): 612-616. (ZHANG Rong-tang, CHEN Shou-yi. An experimental study on stress-strain behavior of soft clay along decreasing average normal stress[J]. Rock and Soil Mechanics, 2002, 23(5): 612-616. (in Chinese)) [5] 刘国彬, 侯学渊. 软土的卸荷模量[J]. 岩土工程学报, 1996, 18(6): 18-23. (LIU Guo-bin, HOU Xue-yuan. Unloading modulus of the Shanghai soft clay[J]. Chinese Journal of Geotechnical Engineering, 1996, 18(6): 18-23. (in Chinese)) [6] BOLTON M D. The strength and dilatancy of sands[J]. Géotechnique, 1986, 36(1): 65-78. [7] LADE P V, DUNCAN J M. Cubical triaxial tests on cohesionless soil[J]. Journal of the Soil Mechanics and Foundations Division, 1973, 99(10): 793-812. [8] 邵生俊, 许萍, 王强, 等. 黄土各向异性强度特性的真三轴试验研究[J]. 岩土工程学报, 2014, 36(9): 1614-1623. (SHAO Sheng-jun, XU Ping, WANG Qiang, et al. Anisotropic strength characteristics of loess in true triaxial tests[J]. Chinese Journal of Geotechnical Engineering, 2014, 36(9): 1614-1623. (in Chinese)) [9] 李滨, 刘瑞琦, 冯振, 等. Q 3 砂黄土真三轴强度变形特性研究[J]. 岩土力学, 2013, 34(11): 3127-3133. (LI Bin, LIU Rui-qi, FENG Zhen, et al. Strength and deformation characteristics of Q 3 sand loess under true triaxial condition[J]. Rock and Soil Mechanics, 2013, 34(11): 3127-3133. (in Chinese)) [10] 盛佳韧, 武朝军, 叶冠林, 等. 上海黏土强度特性真三轴试验研究[J]. 岩土力学, 2013, 34(1): 47-52. (SHENG Jia-ren, WU Chao-jun, YE Guan-lin, et al. Strength property of Shanghai clay in true triaxial tests[J]. Rock and Soil Mechanics, 2013, 34(1): 47-52. (in Chinese)) [11] 许成顺, 刘海强, 杜修力, 等. 动态土工真三轴仪在砂土液化研究中的应用[J]. 岩土工程学报, 2013, 35(10): 1895-1900. (XU Cheng-shun, LIU Hai-qiang, DU Xiu-li, et al. Application of dynamic true triaxial apparatus to study on sand liquefaction[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(10): 1895-1900. (in Chinese)) [12] 邓国华, 邵生俊. 基于真三轴试验的黄土结构性变化规律研究[J]. 岩土力学, 2013, 34(3): 679-684. (DENG Guo-hua, SHAO Sheng-jun. Research on change structural characteristics of loess based on true triaxial tests[J]. Rock and Soil Mechanics, 2013, 34(3): 679-684. (in Chinese)) [13] 叶冠林, 盛佳韧, 武朝军, 等. 自动控制真三轴仪的研制及验证[J]. 岩土工程学报, 2011, 33(3): 380-385. (YE Guan-lin, SHENG Jia-ren, WU Chao-jun, et al. Design and verification of automatic true triaxial apparatus[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(3): 380-385. (in Chinese)) [14] 石建刚, 邵生俊, 陶虎, 等. 非饱和土的真三轴试验及强度变形特性分析[J]. 岩土工程学报, 2011, 33(增刊1): 85-90. (SHI Jian-gang, SHAO Sheng-jun, TAO Hu, et al. True triaxial tests and strength deformation behaviors of unsaturated soils[J]. Chinese Journal of Geotechnical Engineering, 2011, 33(S1): 85-90. (in Chinese)) [15] SHI W C, ZHU J G, CHIU C F, et al. Strength and deformation behaviour of coarse-grained soil by true triaxial tests[J]. Journal of Central South University of Technology, 2010, 17(5): 1095-1102. [16] 殷建华, 周万欢, KUMRUZZAMAN Md, 等. 新型混合边界真三轴仪加载装置及岩土材料试验结果[J]. 岩土工程学报, 2010, 32(4): 493-499. (YIN Jian-hua, ZHOU Wan-huan, KUMRUZZAMAN Md, et al. New mixed boundary true triaxial loading device for testing study on 3-D stress-strain-strength behaviour of geomaterials[J]. Chinese Journal of Geotechnical Engineering, 2010, 32(4): 493-499. (in Chinese)) [17] 殷宗泽, 徐志伟. 土体的各向异性及近似模拟[J]. 岩土工程学报, 2002, 24(5): 547-551. (YIN Zong-ze, XU Zhi-wei. Anisotropy of soils and its approximate simulation[J]. Chinese Journal of Geotechnical Engineering, 2002, 24(5): 547-551. (in Chinese)) [18] XIAO Y, LIU H L, ZHU J G, et al. Dilatancy equation of rockfill material under the true triaxial stress condition[J]. Science China Technological Sciences, 2011(S1): 175-184. [19] XIAO Yang, LIU Han-long, ZHU Jun-gao, et al. A 3D bounding surface model for rockfill materials[J]. Science China Technological Sciences, 2011, 54(11): 2904-2915. [20] 朱俊高, 翁厚洋, 吴晓铭, 等. 粗粒料级配缩尺后压实密度试验研究[J]. 岩土力学, 2010, 31(8): 2394-2398. (ZHU Jun-gao, WENG Hou-yang, WU Xiao-ming, et al. Experimental study of compact density of scaled coarse-grained soil[J]. Rock and Soil Mechanics, 2010, 31(8): 2394-2398. (in Chinese))