中主应力系数和主应力方向对原状黏土各向异性的影响研究  

STUDY OF INFLUENCE OF PARAMETERS OF INTERMEDIATE PRINCIPAL STRESS AND PRINCIPAL STRESS DIRECTION ON ANISOTROPY OF INTACT CLAY

作　　者：管林波[1] 周建[1] 张勋[1] 谢新宇[1] 

机构地区：[1]浙江大学岩土工程研究所,浙江杭州310058

出　　处：《岩石力学与工程学报》2010年第A02期3871-3877,共7页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(50778162);浙江省留学回国基金项目(J20090026);"十一五"国家科技支撑计划项目(2008BAJ06B01–4)

摘　　要：针对当前土体各向异性影响因素的研究比较缺乏,且研究对象多为无黏性土的现状,采用空心圆柱扭剪仪对中主应力系数和主应力方向变化情况下的杭州典型原状黏土的各向异性进行研究。试验结果表明:剪切过程中,中主应力系数b的取值对原状黏土的各向异性有显著影响,而主应力作用方向对原状黏土的各向异性无明显影响。b=0时,原状黏土沿沉积方向呈横观各向同性。b=0.5时,无论主应力作用方向如何,原状黏土试样的各向异性在应变上表现为轴向应变与切向应变大小相等、方向相反,体积应变始终等于第二主应变;当主应力轴偏转角较小时,试样破坏时表现出明显的剪胀性和应变软化现象,随着主应力轴的偏转角增大,试样在破坏时开始表现出明显的剪缩性,应变软化现象也逐渐消失,而b=0时则没有这样的特点。另外试验结果还表明,原状黏土在沉积方向上的压缩性最低,而与沉积方向成50°方向的压缩性最高。There was lack of knowledge about the anisotropy of soft intact clay since most studies were performed on cohesionless soils. A hollow cylinder apparatus（HCA） is used to study the anisotropy of typical Hangzhou intact clay to investigate the influence of the parameters of intermediate principal stress and the principal stress direction on anisotropy. It is revealed that the anisotropy of intact clay is greatly affected by the value of the parameters of intermediate principal stress b,and is hardly affected by the principal stress direction. The intact clay is transversely isotropic along the depositional plane when b equals zero. When b equals 0.5,the characteristic of anisotropy is different. Regardless of the direction of the principal stress,the radial strain and the tangential strain of the sample always equal in magnitude and opposite in direction. Meanwhile the volumetric strain of intact clay is equal to the value of the second principal strain. Apparent dilatancy and strain softening are observed when samples fail at small rotation angle. Shrinking is significantly noticed in the beginning of failure with the increase of the rotation angle,while strain softening gradually vanishes. All these phenomena are not observed in b equaling tests. Test results also present that the intact clays have the lowest compressibility along the direction of deposition and the highest compressibility along the direction of rotation angle 50°.

关 键 词：土力学 中主应力系数 主应力方向 各向异性 主应力轴旋转 原状软粘土 

分 类 号：TU435[建筑科学—岩土工程]