膨胀土非线性蠕变模型研究  

Study on the nonlinear creep model of expansive soil

作　　者：宁行乐 肖宏彬[1] 张春晓[1] 何彬[1] 谢佳佑 

机构地区：[1]中南林业科技大学土木工程与力学学院,湖南长沙410004

出　　处：《自然灾害学报》2017年第1期149-155,共7页Journal of Natural Disasters

基　　金：国家自然科学基金项目(50978097);湖南省科技厅资助项目(2010SK3047)~~

摘　　要：通过对南宁膨胀土的三轴压缩蠕变试验,研究了该膨胀土的非线性蠕变特性。基于流变力学和分数阶微积分理论的蠕变模型,构建了可反映膨胀土非线性流变特性的本构方程和蠕变方程。为了更好地描述膨胀土的非线性流变行为,通过引入考虑应力水平影响的类粘滞系数,进一步改进了软体元件。研究发现,膨胀土的非线性蠕变过程可以通过调整分数阶次β1和β2进行有效地模拟。研究结果表明,所建立的模型能完整地描述膨胀土的粘-弹-塑性变形,且模型分析结果与试验结果非常吻合,为计算膨胀土地基在长期荷载作用下的变形提供了理论依据,也对进一步探索膨胀土的应力松弛和长期强度等流变特性具有理论意义。The nonlinear creep characteristics of Nanning expansive soil were been studied through a series of indoor triaxial creep compression tests of the soil. Based on creep model of rheological mechanics and fractional calculus theory, the constitutive equation and creep equation which may reflect the nonlinear rheological characteristic of expansive soils were constructed. In order to describe the nonlinear rbeological charateristics of expensive soil better, the soft-matter element was modified furthermore by introducing an apparent viscosity coefficient which may considers the influence of stress level. It is found that the nonlinear creep process of expansive soil can be simulated effectively by adjusting the fractional orders β1 and β2. Results indicate that the established model may discribe visco-elastoplastic creep deformation of expansive soil perfectly, and the model analysis results are quite close to the test one. The research results not only provides a theoretical basis for the calculation of deformation of expansive soil foundation under long-term loads, but also have the theoretical significance for the further exploring the nonlinear rheological characteristics such as the stress relaxation and the long-term strength of expansive soil.

关 键 词：膨胀土 分数阶微积分 非线性流变 蠕变模型 

分 类 号：TU443[建筑科学—岩土工程]