不同含水率与围压下伊犁高温冻土三轴力学试验特性研究

Experimental Study on Triaxial Mechanical Properties of High−Temperature Frozen Loess under Different Moisture Content and Confining Pressure in Yili, Xinjiang

为了探究含水率与围压变化对高温冻土物理力学性质的影响,以新疆伊犁河谷高温冻结黄土为研究对象,开展了黄土的矿物成分、物理性质,以及不同含水率和围压条件下冻土的三轴压缩试验。结果表明:伊犁黄土的粉粒与黏粒粒组含量占比较高,对冻融作用的反应敏感。低含水率时表现为应变软化现象,破坏形态以脆性剪切破坏为主,饱和含水率时表现为应变硬化现象,破坏形态以塑性鼓胀变形破坏为主,软化系数随含水率增大而逐渐减小。随着含水率增大,峰残内摩擦角逐渐降低,峰残黏聚力逐渐增大,变形模量逐渐增大。随着围压增大,弹性模量和损伤演化特征参数均逐渐降低,引入的损伤力学本构模型能够较好地描述高温冻土在不同含水率和围压影响下的应力应变全过程。研究成果可为伊犁河谷冻融滑坡成灾机理研究提供力学参数与理论依据支撑。

In order to explore the influence of moisture content and confining pressure on the physical and mechanical properties of high−temperature frozen loess,taking the loess as the research object in Yili valley,Xinjiang.The mineral composition and physical properties of loess,as well as the triaxial compression tests under different moisture content and confining pressure were carried out.The results show that the content of silt and clay is high in Yili loess,which is sensitive to freezing−thawing.At low water content,the failure mode is strain softening and brittle shear failure,while at saturated water content,the failure mode is strain hardening and plastic bulging deformation failure.The softening coefficient decreases gradually with water content increasing. With the increase of water content, the peak residual friction angle gradually decreases, the peak residual cohe-sion gradually increases, and the deformation modulus increases. With the increase of confining pressure, the elastic modulus and characteristic parameters of damage evolution gradually decrease, and the damage mechan-ics constitutive model introduced can better describe the whole process of stress and strain of high−temperature frozen loess under different water content and confining pressure. The research results can provide mechanical parameters and theoretical basis for the study of mechanism of freeze−thaw landslide in Yili Valley.