冻结膨胀土应力-应变关系试验研究

Experimental study of stress-stain relationships of frozen expansive soil

通过冻结膨胀土三轴力学试验,主要研究了土体在不同温度与围压条件下的应力-应变关系.结果表明:冻结膨胀土的应力-应变曲线为应变硬化型,具有明显的弹塑性变形阶段;在相同围压条件下,随着温度的降低,偏应力增量随应变的增加而增大,最终达到塑性破坏时应力也随之增大.通过回归分析,抗压强度与温度呈良好的线性关系.随着围压的增加,土体进入塑性变形阶段时的应力有所提高,抗压强度也随之增加,相比温度,围压对抗压强度的影响不是很大.对试验数据进行拟合表明,应用邓肯-张模型能够很好的描述冻结膨胀土应力-应变关系.

Through the triaxial mechanical test of frozen expansive soil, the stress-strain relationships are studied under different temperatures and confining pressures. The results indicate that the stress-strain curves of frozen expansive soil all show the property of stain hardening. It is found that the deformation stage of elastic-plastic is very obvious. With decreasing temperature, the increment of deviatoric stress increases gradually in the process of deformation, and the plastic failure stress is also increases. Meanwhile, a good linear relationship between compressive strength and temperature is showed by regression analysis. With the increase of confining pressure, the stress and compressive strength increase when the soil attains the plastic deformation stage. As compared with temperature, the confining pressure influence on compressive strength is not so distinct. For fitting the experimental data, the stress-strain relationships can be described commendably through Duncan-Chang model.