非饱和土三剪强度准则及验证  

Triple-shear failure criteria and experimental verification for unsaturated soils

作　　者：陈昊 胡小荣[1] CHEN Hao;HU Xiao-rong(School of Civil Engineering and Architecture,Nanchang University,Nanchang,Jiangxi 330031,China)

机构地区：[1]南昌大学建筑工程学院,江西南昌330031

出　　处：《岩土力学》2020年第7期2380-2388,共9页Rock and Soil Mechanics

基　　金：国家自然科学基金(No.10862004,No.11362016)。

摘　　要：基于材料三剪强度准则和非饱和土力学特性,提出了非饱和土的单应力变量和双应力变量三剪强度准则,并对其做了特征分析。分析表明,通过改变准则中的主应力影响系数b,所提准则就可以对其他强度准则进行非线性近似表达。在π平面的极限线中,所提强度准则覆盖了由内边界的单剪强度准则到外边界的三剪统一强度准则之间的所有外凸区域。因此,其适用于各种复杂应力状态下的非饱和土体,也能反映非饱和土单轴抗拉抗压强度不等的特征。另外,还用其他文献的真三轴试验数据对所提准则做了试验验证,其中,非饱和黏土砂的真三轴试验值与中主应力影响系数b=0.6时的三剪强度准则预测值吻合较好,双应力变量下准则的预测值比单应力变量下的预测值更符合试验值;非饱和黄土真三轴试验值与中主应力影响系数b=0.2时的三剪强度准则预测值吻合较好,两种应力变量下的三剪强度准则预测值差别较小。Based on the triple-shear failure criterion of materials and the mechanical properties of unsaturated soils,the triple-shear failure criteria of the single stress variable and the double stress variable for unsaturated soils are put forward,and their characteristics are analyzed.The results show that the existing failure criteria for unsaturated soils can be interpreted approximately with the new criteria by changing the influence coefficient b of the principal stress.For loci on theπplane,the failure criteria proposed in this paper cover all the convex regions from the inner boundary of the single-shear failure criterion to the outer boundary of the triple-shear failure criterion.Therefore,the new criteria are suitable for unsaturated soils under various complex stress states and can reflect the inequality in uniaxial tension and compression of the unsaturated soils.In addition,several true triaxial test results reported by other researchers are adopted to verify the proposed criteria.For the unsaturated clayey sands,the true triaxial test results were found in good agreement with the values predicted by the triple-shear failure criteria of the single stress variable and the double stress variable when the influence coefficient of the principal stress b=0.6,and the predicted values given by the double stress variable criterion are more consistent than that of the single stress variable criterion.For the unsaturated loess,true triaxial test values are also in good agreement with the values predicted by the triple-shear failure criteria when the influence coefficient of principal stress b=0.2,and the difference is smaller between the two kinds of triple-failure failure criteria than that of the clayey sands.

关 键 词：非饱和土 三剪强度准则 单应力变量 双应力变量 试验验证 

分 类 号：TU411[建筑科学—岩土工程]