ELASTO-PLASTIC DEFORMATION BEHAVIOR OF INTACT CLAY SUBJECTED TO PRINCIPAL STRESS ROTATION
YAN Jiajia1，2，ZHOU Jian1，2，LIU Zhengyi1，2，GONG Xiaonan1，2
(1. College of Civil Engineering and Architecture，Zhejiang University，Hangzhou，Zhejiang 310058，China；2. Research Center of Coastal and Urban Geotechnical Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China)
Abstract：A series of undrained pure principal stress rotation and cyclic principal stress rotation tests were carried out on intact clay using a hollow cylinder apparatus. The magnitudes of mean principal stress，shear stress and intermediate principal stress parameter were kept constant during principal stress rotation. The elastic parameters were obtained from the cyclic loading-unloading tests. The elastic and plastic deformation behavior of intact clay induced by pure principal stress rotation was studied. The direction of the plastic strain increment was investigated. Test results show that both the elastic and plastic strain are induced by principal stress rotation alone in undrained condition，the directions of the elastic and plastic strain increment deviated from the principal stress axis. The development of strains is influenced by the intermediate principal stress parameter. The non-coaxial plastic behavior of soil will be overestimated if the influence of elastic strain is not taken into consideration. The plastic strain induced by principal stress rotation depends on both the coaxial and non-coaxial plastic mechanisms.
ISHIHARA K，TOWHATA I. Sand response in cyclic rotation of principal stress directions as induced by wave loads[J]. Soils and Foundations，1983，24(3)：11-26.
[2]
YANG Z X，LI X S，YANG J. Undrained anisotropy and rotational shear in granular soil[J]. Geotechnique，2007，57(4)：378-384.
[3]
AKAGI H，SAITOH J. Dilatancy characteristics of clayey soil under principal axes rotation[C]// Proceedings of the International Symposium on Prefailure Deformation Characteristics of Geomaterial. Sapporo：[s. n.]，1994：311-314.
[4]
NAKATAY，HYODO M.，MURATAH.Non-coaxiality of sand subjected to principal stress rotation[C]// Proceedings of the InternationalSymposium on Prefailure Deformation Characteristics of Geomaterial.Sapporo：[s. n.]，1994：265-270.
[5]
SYMES M J，GENS A，HIGHT D W. Undrained anisotropy and principal stress rotation in saturated sand[J]. Geotechnique，1984，34(1)：11-27
[6]
MIURA K，MIURA S，TOKI S. Deformation behavior of anisotropic dense sand under principal stress axes rotation[J]. Soils and Foundations，1986，26(1)，36-52.
[7]
NAKATA Y，HYODO M，MURATA H，et al. Flow deformation of sandssubjected to principal stress rotation[J]. Soils and Foundations，1998，38(2)：115-128.
[8]
LIN H，PENUMADU D. Experimental investigation on principal stress rotation in Kaolin clay[J]. Journal of Geotechnical and Geoenvironmental Engineering，ASCE，2005，131(5)：633-642.
[9]
GUTIERREZM，ISHIHARAK，TOWHATAI.Flow theory for sand during rotation of principal stress direction[J]. Soils and Foundations，1991，31(4)：121-132.
[10]
TONGZX，ZHANG JM，YU YL，et al. Drained deformation behavior of anisotropic sands during cyclic rotation of principal stress axes[J]. Journal of Geotechnical and Geoenvironmental Engineering，2010，136(6)：1509-1518.
[11]
CAI Y Y，YU H S，WANATOWSKI D，et al. Noncoaxial behavior of sand under various stress paths[J]. Journal of Geotechnical and Geoenvironmental Engineering，2013，139(8)：1509-1518.
[12]
苏佳兴，蒋明镜，李立青，等. 偏应力比及中主应力系数对应力主轴偏转条件下干砂变形特性的影响[J]. 岩土工程学报，2011，33(增1)：448-453.(SU Jiaxing，JIANG Mingjing，LI Liqing，et al. Effects of deviatoric stress ratio and intermediate stress parameter on deformation behaviors of dry sands under principal stress rotation[J]. Chinese Journal of Geotechnical Engineering，2011，33(Supp.1)：448-453.(in Chinese))
[13]
钱建固，黄茂松. 土体变形分叉的非共轴理论[J]. 岩土工程学报，2004，26(6)：777-781.(QIAN Jiangu，HUANG Maosong. Non-coaxiality for deformation bifurcation in soils[J]. Chinese Journal of Geotechnical Engineering，2004，26(6)：777-781.(in Chinese))
[14]
HONG WP，LADEPV.Strain increment and stress directions in torsion shear tests[J].Journal of Geotechnical Engineering-ASCE，1989，115(10)：1388-1401.
[15]
LADE PV，NAMJ，HONGW P.Interpretation of strains in torsion shear tests[J]. Computers and Geotechnics，2009，36(1)：211-225.
[16]
BLANCM，BENEDETTOD，TIOUAJNIS.Deformation characteristics of dry Hostun sand with principal stress axes rotation[J]. Soils and Foundations，2011，51(4)：749-760.
[17]
沈 扬. 考虑主应力方向变化的原状软黏土试验研究[博士学位论文][D]. 杭州：浙江大学，2007.(SHEN Yang. Experimental study on effect of variation of principal stress orientation on undisturbed soft clay[Ph. D. Thesis][D]. Hangzhou：Zhejiang University，2007.(in Chinese)).
[18]
郑鸿镔 主应力轴旋转下重塑粘土与原状粘土特性试验研究[硕士学位论文][D]. 杭州：浙江大学，2011.(ZHENG Hongbin. Experimentalstudy of reconstituted clay and intact clay under principal stress rotation[M. S.Thesis][D]. Hangzhou：Zhejiang University，2011.(in Chinese)).
[19]
OHTA H，SEKIGUCHI H. Constitutive equations considering anisotropyand stress reorientation in clay[C]// Proceedings of the 3rd International Conference on Numerical Methods in Geomechanics. Aachen：[s. n.]，1979：475-484.
2014, Vol. 33 
