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1、第36卷第9期岩土工程学报Vol.36No.92014年.9月ChineseJournalofGeotechnicalEngineeringSep.2014DOI:10.11779/CJGE201409007黄土各向异性强度特性的真三轴试验研究1,21,211,2邵生俊,许萍,王强,代亚锋(1.西安理工大学土木学院岩土工程研究所,陕西西安710048;2.陕西省黄土力学与工程重点实验室,陕西西安710048)摘要:黄土水平面内沉积结构及其发育的竖向裂隙构造使其具有明显的各向异性特征。通过黄土竖直裂隙
2、向及其正交方向作用三维主应力状态几何空间八面体平面上3个空间域的真三轴试验,揭示了各空间域不同中主应力比值应力路径的剪切应力应变变化规律及抗剪强度变化规律。表明黄土竖向裂隙向作用大主应力的抗剪应力均大于水平面内正交两向作用大主应力的抗剪应力;中主应力增强作用能够诱导黄土的各向异性结构性;横观各向同性或者各向异性黄土八面体面上的强度破坏面随着平均球应力增大均呈椭圆、圆和曲边三角形变化,椭圆形破坏面可分别由轴对称压缩空间滑动面强度准则或轴对称挤伸空间滑动面强度准则近似地描述。关键词:各向异性;强度特性;
3、强度破坏面;黄土中图分类号:TU43文献标识码:A文章编号:1000–4548(2014)09–1614–10作者简介:邵生俊(1964–),男,甘肃武威人,教授,博士生导师,主要从事土动力学与黄土力学研究。E-mail:sjshao@xaut.edu.cn。Truetriaxialtestsonanisotropicstrengthcharacteristicsofloess1,21,211,2SHAOSheng-jun,XUPing,WANGQiang,DAIYa-feng(1.Institut
4、eofGeotechnicalEngineering,Xi'anUniversityofTechnology,Xi'an710048,China;2.ShaanxiKeyLaboratoryofLoessMechanicsandEngineering,Xi'an710048,China)Abstract:Thestructureofloessconsistingofhorizontallydepositedplanesandverticallyextendedmicro-fracturesmakes
5、theanisotropicstrengthbehaviorofloessremarkable.Throughtriaxialtests,threeprincipalstressesarealternativelyloadedonloessspecimensalongthedirectionofverticalmicro-fractureandtwoorthogonaldirectionsinhorizontallydepositedplane,whosestressconditionsareres
6、pectivelycorrespondingtothreesectorsintheoctahedralplaneofgeometricspace.Theexperimentalresultsrevealthelawsofshearstress-strainandstrengthunderdifferentstresspathsthattheshearstresswhenthemajorprincipalstressisappliedinthedirectionofverticalfractureis
7、commonlylargerthanoneduringthemajorprincipalstressisloadedinthetwoorthogonaldirections;thelargerintermediateprincipalstresscaninducemoresignificantanisotropicstructureofloess;theyieldlociintheoctahedralplaneforcross-isotropicorcross-anisotropicloessapp
8、eartobeelliptical,circularandtriangularwithcurvededgeschangingwiththeincreaseofsphericalstress,andellipticalyieldlocuscanbeapproximativelyexpressedbythestrengthcriterionofAC-SMPorAE-SMP.Keywords:anisotropy;strengthcharacteristic;yieldsu