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对黄河岸滩饱和粉土在固结不排水条件下进行了一系列单调加载、循环荷载后单调加载的三轴试验,研究了动应力幅值、围压及动孔压比对循环荷载后力学特性的影响,提出了可考虑围压及动孔压比影响的粉土循环荷载后单调加载应力应变关系的变形模式。试验结果表明:循环荷载作用完全液化时,动应力幅值变化对液化后力学特性的影响很小;循环荷载后单调加载的有效应力临界状态线与单调加载时相同,不受循环荷载作用历史的影响。与单调加载时相比,循环荷载后的不排水强度及初始切线模量皆产生衰化,衰化程度随动孔压比的增大而增大,初始切线模量的衰化程度更明显;不同围压下循环荷载后的不排水强度比、初始切线模量比及破坏比,皆与动孔压比之间有良好的归一化关系;粉土循环荷载后的应力应变关系可以用双曲线模型来描述,模型计算值与试验实测值基本吻合。
A series of triaxial tests of monotonous loading and monotonous loading after cyclic loading were carried out on the undisturbed undrained condition of the Yellow River beach saturated silt. The effects of dynamic stress amplitude, confining pressure and moving-hole pressure ratio on the mechanical behavior after cyclic loading The deformation mode of stress-strain relationship of monotonic loading on silty soil subjected to cyclic loading considering the influence of confining pressure and moving-pore pressure ratio is proposed. The experimental results show that when the cyclic loading is completely liquefied, the change of dynamic stress amplitude has little effect on the mechanical properties after liquefaction. The critical stress state of monotonic loading after cyclic loading is the same as that of monotonic loading and is independent of the history of cyclic loading influences. Compared with the monotonous loading, the undrained strength and the initial tangent modulus after cyclic loading all decreased, and the degree of degradation increased with the increase of the moving pore ratio, and the initial tangent modulus became more pronounced. Under different confining pressure, the ratio of undrained drainage strength, initial tangent modulus ratio and failure ratio have a good normalized relationship with the ratio of moving hole and hole pressure. The stress-strain relationship of silt under cyclic loading can be expressed as double Curve model to describe, the calculated value of the model is basically consistent with the measured value of the experiment.