Analysis of Strength Characteristics of Q3 Loess in Continuously Humidified Conditions
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摘要: Q3黄土是一种湿陷性较强的黄土,浸水饱和后,其湿陷性消失进而转化为高压缩性土,一般在天然状态下处于欠压密状态,具有压缩性高、变形量大、承载力低、工程性差等特点,易导致工程事故的发生。采用GDS非饱和土三轴仪对不同初始上覆荷载条件下连续增湿的Q3黄土进行常规三轴试验,研究Q3黄土的应力-应变关系及强度特性。结果表明:连续增湿过程中,Q3黄土的应力-应变曲线均呈硬化型,增湿程度越小、固结压力越大,应力-应变曲线越高;初始上覆荷载在0~100 kPa时,应力-应变曲线上升幅度较低平,超过100 kPa后,应力-应变曲线上升逐步陡峭。各试验条件下,p-q强度破坏线近似呈线性关系;Q3黄土的强度与含水率和初始上覆荷载密切相关,随着含水率的增大,黏聚力和内摩擦角均呈非线性衰减;随着初始上覆荷载的增大,黏聚力和内摩擦角均呈先减小后增大趋势。Abstract: Q3 loess is a kind of loess with strong collapsibility. After soaking and saturation in water, its collapsibility disappears and then converts into a high compressibility soil. Generally, it is in an undercompacted state under natural conditions, exhibiting high compressibility, large deformation, low bearing capacity, poor engineering performance, etc., which is easy to lead to engineering accidents. The stress-strain relations and strength characteristics of Q3 loess with continuous humidification under different initial overburden loads were studied by conventional triaxial tests with GDS unsaturated soil triaxial apparatus. The results showed that the stress-strain curves of Q3 loess were hardened in the process of continuous humidification. The smaller the degree of humidification, the greater the consolidation pressure, and the higher the stress-strain curve; when the initial overburden load was 0 to 100 kPa, the rise of the stress-strain curve was low and flat, and when it was greater than 100 kPa, the rise of the stress-strain curve gradually steepened. Under all test conditions, the failure line of p-q strength was approximately linear; the strength of Q3 loess was closely related to its water content and initial overburden load. With the increase of water content, both cohesion and internal friction angle exhibited nonlinear attenuation; with the increase of the initial overburden load, they first decreased and then increased.
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