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用非饱和土三轴剪切渗透仪,在等向应力条件下对原状黄土进行增湿–加载,加载–增湿及加载–增湿–加载3个系列加载增湿路径试验,分析吸力对压缩变形和加载屈服特性的影响,探讨增湿时应力对变形及屈服特性的影响,通过对单线法及双线法的试验结果对比,确认原状黄土的增湿体积变形与加载增湿路径有关,加载及增湿屈服线不具有唯一性,进而提出等向应力条件下原状黄土的弹塑性体变模型。研究结果表明:吸力及应力分别对屈服前压缩及增湿变形特性指标几乎没有影响,而对屈服后的指标皆有明显的影响;单线法与双线法确定的增湿体积变形皆随应力的增大而先增大后减小,峰值点处应力与吸力丧失程度及加载增湿路径无关,且近似等于天然状态土样的初始屈服应力;增湿变形与加载增湿路径有关,单线法的值比双线法确定的值小,差值随增湿程度增大而减小,增湿至饱和时2种方法确定的湿陷变形近似相等。对于相同的塑性体应变,吸力减小屈服线位于加载屈服线之下方,二者随塑性体应变的增大而耦合联动扩大。提出的弹塑性体变模型可以较好地预测不同吸力下的压缩变形,比采用唯一加载湿陷屈服线的模型更好地预测不同应力下增湿变形。
Using unsaturated soil triaxial shear permeameter, the intact loess was humidified-loaded, loaded-humidified and loaded-humidified-loaded with three series of loading humidification paths under the condition of isotropic stress. The effects of suction on compression Deformation and loading yield characteristics of the impact of stress on deformation and yield characteristics when wetting, by comparing the single-line method and the two-wire test results confirm that undisturbed loess humidification volume deformation and loading humidification path related to loading And humidification yield line is not unique, and then put forward the elastic-plastic deformation model of undisturbed loess under the condition of equal stress. The results show that the suction and the stress have little influence on the deformation and wetting deformation before yielding, respectively, but have obvious influence on the yield after yielding. The deformation of the wetting volume determined by the single-line method and the double-line method both vary with the stress Increase first and then decrease, peak stress at the point of suction loss and the degree of loading and humidification path has nothing to do, and is approximately equal to the initial state of natural soil yield stress; humidification deformation and loading humidification path, single-line method The value is smaller than the value determined by the two-line method, and the difference decreases with the increase of the degree of humidification. The deformations determined by the two methods when the humidification is saturated are approximately equal. For the same plastomer strain, the decrease in suction is below the load line of yield, both of which increase as the strain of the plastomer increases and the coupling increases. The proposed elastoplastic deformation model can predict the compressive deformation under different suction better than the model which uses the only loading wetting yield line to predict the wetting deformation under different stresses.