横观各向同性砂土的破坏准则  

Failure criterion for transversely isotropic sands

作　　者：杨雪强[1] 张丽娟[1] 燕全会[1] 张新涛[1] 

机构地区：[1]广东工业大学土木与交通工程学院,广州510006

出　　处：《应用力学学报》2013年第3期304-310,469-470,共7页Chinese Journal of Applied Mechanics

基　　金：广东省教育厅科研基金(2008278)

摘　　要：对砂土类材料,各向异性状态参数定义为材料微观结构张量与标准化偏应力张量之间的联合不变量。通过在Lade破坏准则内耦合各向异性状态参数,建立了横观各向同性砂土类材料的破坏准则,并分别结合中密和密实的Santa Monica河滩砂的扭剪和真三轴实验资料进行了验证工作。研究结果表明:局部剪切带、加荷方向与材料主轴方向间的相对方位是影响砂土内摩擦角的主要因素;与扭剪实验和真三轴实验进行验证时均发现,当中主应力比b在0.18-0.85范围内时,由于砂样易出现局部的剪切带,这使砂样在达到其真正的峰值强度前破坏,从而使预测出的砂土内摩擦角均大于其实测值;但当b≤0.18和b≥0.85时,砂样始终呈现无剪切带的均匀变形破坏,因此预测出的砂土内摩擦角基本等于其实测值。这些研究结果说明了该横观各向同性砂土的破坏准则是合理的。For sands,based on the Lade failure criterion,a transversely isotropic failure criterion is established by incorporating an anisotropic state scalar parameter which is a joint invariant of microstructure fabric tensor and normalized deviatoric stress tensor,and is verified by torsional shear and true triaxial compressive testing data of medium dense and dense Santa Monica beach sands.The results show that shear band and relative orientation between loading direction and principal direction of the transversely isotropic microstructure of sand are main influencing factors on testing internal frictional angles of sand samples;when b =(0.18,0.85),whether for torsional shear or true triaxial compressive tests,predicted internal frictional angles of sand are bigger than actual testing frictional angles because the shear band occurs locally to induce sand sample breakage before the sand sample approaching its real peak strength;when b ≤ 0.18and b≥ 0.85,the predicted internal frictional angles of sand agree with testing results because the shear band does not occur in sand sample and sand sample always deforms uniformly.These results show that the transversely isotropic failure criterion proposed in the paper is reasonable.

关 键 词：破坏准则 横观各向同性 各向异性状态参数 组构张量 偏应力张量 

分 类 号：TU459[建筑科学—岩土工程]