考虑温度对静止土压力K_(0)系数影响的统一硬化本构模型

Unified hardening constitutive model considering the influence of temperature on K_(0) coefficient

K_(0)系数是重要的岩土工程参数,研究其影响因素和变化规律对合理确定地基应力状态至关重要。本研究通过试验和理论方法研究了温度对饱和黏性土K_(0)系数的影响。首先,以饱和标准砂-膨润土混合土样为对象,开展不同温度下的侧限压缩试验,获得了K_(0)系数随温度的变化规律,发现正常固结土的K_(0)系数随升温而减小,超固结土的K_(0)系数随升温而轻微增大;其次,推导出K_(0)系数与弹塑性屈服面偏转度之间的定量关系,并将其与温控侧限压缩试验结果结合,获得了屈服面偏转度随温度的变化规律;最后,将屈服面偏转度-温度关系引入统一硬化本构模型理论框架,建立了考虑温度对K_(0)系数影响的饱和黏性土弹塑性本构模型。所提出的模型能够较好地模拟多种类型的室内土力学试验。

The K_(0) coefficient is an important geotechnical parameter.Investigating its influencing factors and change law is vital for determining ground stress states.The influence of temperature on the K_(0) coefficient was investigated in this paper using experimental and theoretical methods.Firstly,some confined compression tests at different temperatures were conducted on saturated mixture samples of standard sand and bentonite.The change law of the K_(0) coefficient with temperature was obtained,indicating that the K_(0) coefficient of normally consolidated soils decreases but that of overconsolidated soils increases slightly as temperature increases.Secondly,a quantitative relationship between the K_(0) coefficient and the inclination of the elastoplastic yield surface was derived,which was then combined with the results of the temperature-controlled confined compression test.Thus,the variation of the inclination of the yield surface with temperature was obtained.Finally,by introducing the relationship between the inclination of yield surface and temperature into the theoretical framework of the unified hardening constitutive model,a new elastoplastic constitutive model for saturated clayey soils considering the temperature effect on the K_(0) coefficient was established,which can well simulate various laboratory mechanical tests.