CREEP BEHAVIOR OF ZHANJIANG STRONG STRUCTURED CLAY BY DRAINED TRIAXIAL TEST
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;2. Fourth Harbour Engineering Investigation and Design Institute Co.,Ltd.,China Communications Construction Company,Guangzhou,Guangdong 510230,China)
Abstract:The drained triaxial shear creep tests for Zhanjiang strong structured clay under different confining pressures by GDS triaxial testing system are performed. The relationships of axial strain and volumetric strain with stress and time are obtained. The effect of soil structural property on its creep behavior is analyzed;and the corresponding creep model is established. The results show that the evolution characteristics of creep deformation of Zhanjiang clay are restricted by its poorly structural property;and its sensitivity is related to the structural property of soil. The creep deformation and deformation rate of Zhanjiang clay are small in the range of low deviatoric stress;when the deviatoric stress exceeds a critical value,the soil mass failure occurs in a short time. The overall behavior of volumetric strain of Zhanjiang clay in the process of drained triaxial shear creep presents shear contraction,while a certain shear contraction and shear dilation alternately appear during the creep time under the condition of ?3<?k,i.e. there exists rebound phenomenon;and it presents shear contraction when ?3≥?k. The strength attenuation induced by creep mainly results in cohesion reduction,and 77.63%. It is found that the six-element extended Burgers model could effectively describe the three deformation stages of the instantaneous elastic strain,attenuation creep and stable creep for Zhanjiang clay. In actual project,the soil structural property should be clearly understood;the favorable factors of structural property of soil could be used in low stress level;but the designed load is forbidden to exceed the structural yield stress.
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