西安地区Q_2黄土非线性流变模型  

Nonlinear rheological model for Q_2 loess in Xi'an region

作　　者：谢星[1] 赵法锁[2] 王东红[3] 

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054 [2]长安大学地质工程研究所,陕西西安710054 [3]机械工业勘察设计研究院,陕西西安710043

出　　处：《长安大学学报（自然科学版）》2009年第5期41-46,共6页Journal of Chang’an University(Natural Science Edition)

基　　金：科技部项目(2002CCC00200)

摘　　要：为了研究Q2黄土的流变特性,对西安地区不同湿度的Q2黄土进行了室内单轴蠕变试验和不同围压下的三轴蠕变试验,得到了不同湿度Q2黄土的单轴、三轴蠕变曲线和应力-应变等时曲线。分析试验曲线表明:加载瞬时,Q2黄土具有一瞬时变形,当应力水平低于某一临界值时,蠕变变形是衰减稳定的,在较高的应力作用下,会出现加速蠕变阶段;等时曲线在较低应力下近似于直线,在较高应力下表现为曲线,反映出Q2黄土具有明显的非线性流变特性;根据Q2黄土非线性流变特性,用广义Kelvin模型模拟其粘弹性阶段,用Maxwell模型描述Q2黄土的线性粘塑性特性,非线性粘塑性蠕变可用一幂函数形式的经验模型来描述。在此基础上,分别建立了单轴和三轴条件下不同含水量的Q2黄土的非线性流变本构模型,并通过拟牛顿法确定了相应的模型参数。经验证,该非线性流变模型能够较好地描述Q2黄土的流变特性。In order to study the rheological characters of Q2 loess, the indoor uniaxial and triaxial creep tests under different pressure of Q2 loess with different water contents in Xi＇an are carried out, the uniaxial and triaxial creep curves and tress-train isochronous curves are presented. The results show that： there is instantaneous deformation at the load instant of Q2 loess, the creep deformation is decay stabilization when stress is lower than a critical value, it is acceleration stage when stress is higher; isochronous curves are almost straight line when stress is lower, they are curves when stress is higher, so the Q2 loess have nonlinearity creep properties. On the basis of these, viscoelastic creep phase is simulated by the generalized Kelvin model, linear visco-plastic creep phase is simulated by the Maxwell model, nonlinear visco-plastic creep phase is simulated by the empirical model of power function, the nonlinear uniaxial and triaxial rheological constitutive models of Q2 loess with different water contents are set up, and its parameters are determined by quasi-Newton method. Then the experimental creep curves are simulated. The results indicate that the model can effectively describe the rheological process of Qz loess. 5 tabs, 5 figs, 13 refs.

关 键 词：岩土工程 Q2黄土 非线性 流变特性 流变模型 

分 类 号：TU411[建筑科学—岩土工程] U416.14[建筑科学—土工工程]