冻融循环作用下黄土抗剪强度劣化试验研究

黄土地区冻融现象时常发生,这一气候现象对土体强度劣化显著,影响工程安全建设和正常使用。针对黄陵地区Q2黄土开展不同条件下的三轴剪切试验,探讨含水率、初始围压等因素对黄土抗剪强度的影响规律。结果表明:黄土土样处于相同的含水率和围压的条件下,冻融循环次数对土体内部应力值有较大的影响;土体的黏聚力随着冻融循环次数的增加不断减小,且变化幅度逐渐变小,而土体内摩擦角变化不大。获得冻融次数、含水量和黏聚力三者之间的曲线关系,得到三者之间的拟合公式。试样破坏特征显示:试验后土样的破坏形式主要为剪胀、劈裂和剪切三种类型,随冻融循环次数的增加,破坏形式从剪胀破坏过渡到劈裂破坏。

Experimental Study on Shear Strength Deterioration of Loess under Freeze - thaw Cycling

The phenomenon of freezing and thawing in loess area often occurs. The climate phenomenon has obvious deterioration of soil strength, which affects the construction of safety and the normal use. In this paper, the influence of water content and initial confining pressure on the shear strength of loess is discussed in this paper, based on the triaxial shear test under different conditions of Q2 loess in Huangling area. The results show that the number of freeze-thaw cycles has a great influence on the internal stress value of the soil under the same moisture content and confining pressure. The cohesion of the soil decreases with the increase of the number of freeze-thaw cycles Small, and the change gradually becomes smaller, and the friction angle in the soil is not changed much. The relationship between freezing and thawing times, water content and cohesion was obtained, and the fitting formula between them was obtained. The failure characteristics of the samples show that the failure modes of the soil samples are mainly in the form of dilatancy, splitting and shearing, with the increase of the number of freeze-thaw cycles and the failure of the failure from the dilatancy and failure to the splitting.