摘要
土的蠕变是指在常值应力作用下土的变形随时间而持续增长的现象。沿用传统连续介质力学理论,在土蠕变性质的研究中,人们普遍采用与时间相关的蠕变速率描述土的蠕变行为。然而在工程实际中,土体往往要经历复杂的加卸载过程,并经历不同应力应变状态下的蠕变过程。在此复杂条件下,各个蠕变过程的土的内部结构不同,继续采用传统连续介质力学理论描述土的蠕变行为就遇到了困难。与传统连续介质力学理论不同,内变量理论是一种采用材料内部结构变量(即内变量)描述材料性质的一种理论。据此,提出了土的内变量蠕变模型,该模型采用土的不可恢复应变作为土变形过程中的内变量。模型不但可以反映土所受外部荷载对蠕变行为的影响,而且可以反映材料的内部结构变化对蠕变行为的影响。为验证模型的合理性,开展了复杂条件下砂土和黏土的蠕变性质试验,详细讨论了应力和不可恢复应变对土蠕变性质的影响。此外,还讨论了内变量蠕变模型与传统幂函数蠕变模型参数之间的关系,并提出了一种可以加快蠕变试验的方法。通过研究发现:土的内变量蠕变本构模型可以反映复杂条件下土的蠕变性质。
Soil creep is such a process that the deformation of soil develops with time under a state of constant stress.Following the tradition of continuum mechanics,the time-dependent creep rate is always employed in the investigations of the soil creep.However,in practices,soils undergo complex loading-unloading cycles and are allowed to creep on the stages at different stress and strain levels.In this complex situation,the initial states（or configurations） of the creep stages are different and thus the traditional continuum mechanics is incapable in describing the soil creep.Different from the traditional continuum mechanics,the internal-variable theory is based on the concept of internal variable,which describes the internal structure of materials.In this study,an internal-variable creep model is proposed,in which the creep rate of soils is dependent on not only applied stress,but also irreversible strain,which is adopted as internal variable for soil deformation.A series of laboratory tests have been performed to verify the proposed creep model.The parametric relation between the proposed internal-variable and the traditional power law creep models is derived.A method to accelerate creep tests is proposed based on the proposed creep model.It is found that the proposed internal-variable creep model is capable in describing the soil creep under complex conditions.
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2011年第10期1569-1575,共7页
Chinese Journal of Geotechnical Engineering
基金
岩土力学与工程重点实验室开放课题项目(Z011005)
中国博士后科学基金项目(20110491597)
山东省优秀中青年科学家科研奖励基金项目(BS2011HZ008)
关键词
蠕变
内变量
不可恢复应变
时间相关性
应力相关性
加快蠕变试验方法
creep
internal variable
irreversible strain
time dependency
stress dependency
method to accelerate creep test
