摘要
将三参数黏弹性模型用于描述土工格栅在低应力水平下所表现出的蠕变特性,根据蠕变试验采用最优化方法确定有关模型参数,并证明三参数黏弹性模型能够较准确地反映土工格栅在低应力水平情况下的2个阶段衰减蠕变特性。然后,提出基于土工格栅黏弹特性的加筋土本构模型,得到土处于弹性和塑性阶段时加筋土的应力、应变计算公式。研究结果指出:加筋土中土工格栅应力与加筋土受力、格栅和土的特性、加筋层间距及时间有关;土体进入塑性状态后,土工格栅应力不变,主要表现出蠕变性,导致加筋土的应变随时间增加;随着时间的推移,土工格栅出现应力松弛,它与土体应力逐渐减小;土工格栅埋置于土中时的应力松弛量小于置于空气中的应力松弛量;加筋土塑性状态到达时间Tp受土工格栅的刚度系数E2、黏滞系数η和土的内摩擦角?的影响最大。
The three-parameter viscoelastic constitutive model is applied to describe the creep properties of geogrids at low stress levels.Combining with the creep tests results of geogrids,the model parameters are obtained by using the utmost optimization method.It has been proved that the three-parameter viscoelastic model of geogrids can relatively accurately reflect the two-stage attenuation creep properties of geogrids at low stress levels.Then,one constitutive model of reinforced soil considering viscoelasticity of geogrids is suggested.The stress and strain formulas of reinforced soil when soil is in the elastic and plastic stages are obtained.The study results show that stress of geogrids is not only associated with the external forces that reinforced soil bears,the properties of geogrids and soil,but also with the reinforcement layer spacing and working time.When soil enters into the plastic state,geogrid mainly displays creep properties with its stress changeless,which leads to the increase of strain of reinforced soil with time.As time goes by,geogrid displays stress relaxations;and its stress as well as the stress of soil would decrease.The stress relaxation values of geogrids placed in soil are smaller than that placed in air.Moreover,the stiffness coefficients E2,viscosity coefficient of geogirds and the internal friction angle of soil affect the time required for the reinforced soil arriving at plastic state which is called Tp most.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2011年第4期850-857,共8页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(50778027)
湖南省自然科学基金项目(04JJ3033)
关键词
土力学
土工格栅
应力水平
黏弹性
蠕变特性
加筋土
本构模型
soil mechanics
geogrid
stress level
viscoelasticity
creep properties
reinforced soil
constitutive model
