摘要
基于扰动状态概念研究了正常固结饱和原状黏性土的本构模型。其中,相对完整状态采用基于原状黏性土的理想非线性弹性本构模型来表征;完全调整状态则是基于临界状态土力学框架,将修正剑桥模型与三剪强度准则相结合而建立的弹塑性本构模型来表征。为了更好地反映黏性土的黏聚力影响,提出了等量代换法和坐标平移法两种处理方法,并作了对比研究。针对基于临界状态土力学框架和扰动状态概念建立的原状土本构模型为平均应力、广义剪应力与体应变、广义剪应变间的关系且无屈服函数显式表达式,提出了一个将其三维化的方法。三维化后的原状黏性土本构模型为空间内6个应力分量和6个应变分量之间的关系,更便于复杂应力状态下的土体变形分析及有限元编程。为验证模型的正确性,对正常固结江西原状饱和红黏土土样作了固结排水和固结不排水条件下的常规三轴压缩试验和K0固结试验,并与模型计算结果作了对比,结果表明:所提模型能够较好地反映江西原状饱和红黏土的力学和变形特性。另外,用所提模型对江西原状饱和红黏土进行了真三轴压缩数值模拟实验,探讨了中间主应力对其力学和变形特性的影响,结果表明:中间主应力及其影响系数对土的变形、孔隙水压力、强度均有影响;固结不排水条件下,在相同剪应力的作用下,土体剪应变随中间主应力影响系数的增大而减小,在相同轴向应变条件下,孔隙水压力随中间主应力影响系数的增大而增大;固结排水条件下,在相同平均正应力作用下,土体体应变随中间主应力影响系数的增大而减小,在相同轴向应变条件下,土体体应变随中主应力影响系数的增大而增大。
The triple-shear unified structured constitutive model is proposed for the undisturbed saturated clay in normal consolidation based on the disturbed state concept, in which the relative intact state is characterized by the non-linear elastic model, and the fully adjusted state is characterized by the elasto-plastic model built with the combination of the triple-shear failure criterion and the modified cam-clay model in the critical state soil mechanics. In order to describe the influences of the cohesion on the soil mechanical properties better, two treatments of the equivalent substitution and the coordinate translation are presented and are compared each other. The proposed model may overcome the shortcomings of the modified cam-clay model with the definite failure stress ratio without considering the soil cohesion, which can’t reflect the practical differences of strength properties under different stress states and soil cohesion. The advantage is that the new model shows the practical effects under the different stress states acting on the saturated structured clay with different cohesion better. It features that it can describe the effects of intermediate principal stress, rang changes of stress and difference between tension and compression. Because the given structured constitutive model was built on the disturbed state concept and the critical state soil inmechanics is expressed as the stress-strain relations between the mean stress and the generalized shear stress and the bulk strain and the generalized shear strain, and there is no explicit formulation for the yielding function, a three-dimensionalized method is proposed for the previously given model. The three-dimensionalized structured constitutive model for the undisturbed clay may give relations among the six stress components and the six strain components under the complex stress or strain states, for which it is convenient to use in the practical geotechnical deformation analysis and in the finite element method coding. In order to verify the m
作者
胡小荣
董肖龙
陈晓宇
Hu Xiaorong;Dong Xiaolong;Chen Xiaoyu(School of Civil Engineering and Architecture,Nanchang University,330031,Nanchang,China)
出处
《应用力学学报》
CAS
CSCD
北大核心
2019年第1期36-46,251-252,共12页
Chinese Journal of Applied Mechanics
基金
国家自然科学基金(10862004
11362016)
江西省自然科学基金(20151BAB2002001)
关键词
原状饱和黏性土
本构模型
扰动状态概念
三剪强度准则
江西原状饱和红黏土
undisturbed saturated clay
constitutive model
disturbed state concept
the triple-shear failure criterion
Jiangxi undisturbed saturated lateritic clay
