k_0固结条件下淤泥土排水蠕变特性研究  

Creep characteristics of an oozy soil under drained k_0 consolidation

作　　者：王艳芳[1] 蔡正银[2] 周治刚 关云飞[2] 

机构地区：[1]南京大学金陵学院,江苏南京210093 [2]南京水利科学研究院岩土工程研究所,江苏南京210014 [3]江苏省水利工程科技咨询有限公司,江苏南京210029

出　　处：《岩土力学》2015年第8期2243-2248,共6页Rock and Soil Mechanics

基　　金：水利部公益性行业科研专项(No.201201037);国家自然科学基金项目(No.51179105);国家自然科学基金青年基金(No.51208321)

摘　　要：利用室内试验研究土体蠕变特性时,因受试验条件限制较少开展土体的排水蠕变特性试验研究。对于先还原土体的先期固结条件,然后再开展土体的三轴排水蠕变特性试验的研究更少。为此,以淤泥土为研究对象,通过k0固结三轴排水蠕变试验探讨了饱和淤泥土在轴向加载和侧向减载条件下的排水蠕变特性。由试验数据可知：排水条件下,两种应力路径的轴向蠕变规律基本一致,体积应变明显小于轴向应变,且随时间的延长呈现一定程度的剪缩与剪胀交替性。首次利用三单元力学模型推测出淤泥土的蠕变起始时间为施加偏应力荷载后的100~200 min之间。提出淤泥土蠕变系数的概念并总结其变化规律,得知淤泥土的蠕变系数与偏应力水平密切相关,即不论围压及加载方式如何,蠕变系数均随应力水平增大而增大,且基本呈直线关系,而与前期固结围压大小、蠕变荷载施加方式关系不大。最后提出了淤泥土蠕变本构模型建立的思路,即用南水双屈服面模型描述瞬时变形量和用蠕变经验公式描述蠕变变形量相结合的方式来建立蠕变本构模型。In the experimental study on the creep characteristics of soil, the drained creep experiments are seldom performed due to the restriction of the experimental condition. Even less effort is made to first retrieving the initial consolidation conditions and then conducting the triaxial drainage creep characteristic tests. In this stuy, k0 consolidation creep test is performed in two stress paths including axial loading and lateral unloading to investigate the creep characteristic of saturated silt soil. Based on the experimental results, some conclusions are drawn as follows. First, the axial creep characteristics for the two stress paths are consistent under the drainage conditions, though the volumetric strain is much smaller than the axial strain, and the volumetric strain shows alternating shear shrinkage and shear dilatancy when time elapses. Based on the three-unit mechanical model, the creep starting time of the oozy soil is estimated as 100-200 min after applying the deviatoric stress during the creep test. The creep coefficient of the oozy soil is defined and its variation is characterized. It is found that the creep coefficient is closely related to the deviatoric stress level, i.e., regardless of confining pressure and loading path, creep coefficient increases linearly with deviatoric stress level, and is not influenced by such factors as the initial consolidation confining pressure, load applying way, etc. Finally, it is proposed that the NHRI model describing the transient elastoplastic strain be combined with the creep empirical formulation describing creep strain, so that a creep constitutive model can be developed.

关 键 词：淤泥土 k0固结蠕变试验 蠕变起始时间 蠕变系数 蠕变本构模型 

分 类 号：TU447[建筑科学—岩土工程]