Assessments of the liquefaction resistance of clean sand still involve considerable uncertainties, which are a current research topic in the field of soil liquefaction. The factors considered and discussed in this study include the loading history, degree of saturation, and partial drainage. The effects of each of these factors on pore pressure generation and liquefaction resistance have been studied for decades in the laboratory, and empirical relationships have been derived. In this paper, an attempt is made to explain these effects using the unique index of volumetric strain. A pore pressure generation model is developed which is similar to that of Martin et al. (1975), but based on stress-controlled triaxial tests. The model is verified through comparisons of its results with those of laboratory tests. It is confirmed that the plastic volumetric strain that has accumulated in sand, either by drained or undrained cyclic loading, dominates the increase in the liquefaction resistance of the sand. However, the plastic volumetric strain caused by overconsolidation is less effective in reducing the volumetric strain potential for subsequent cyclic shearing, thus enhancing its resistance to liquefaction. The model provides a better understanding of the physical processes leading to the liquefaction of saturated and unsaturated sand with and without stress history.

净砂抗液化性评价仍存在相当大的不确定性，是目前土壤液化领域的研究课题。本研究中考虑和讨论的因素包括加载历史、饱和度和部分排水。这些因素中的每一个对孔隙压力产生和液化阻力的影响已经在实验室进行了数十年的研究，并得出了经验关系。在本文中，尝试使用独特的体积应变指数来解释这些影响。开发了一种类似于 Martin 等人的孔隙压力生成模型。(1975)，但基于应力控制的三轴试验。该模型通过将其结果与实验室测试结果进行比较来验证。已经证实，通过排水或不排水循环载荷在沙子中积累的塑性体积应变主导了沙子液化阻力的增加。然而，过度固结引起的塑性体积应变在降低随后循环剪切的体积应变潜力方面效果较差，从而增强了其抗液化能力。该模型可以更好地理解导致饱和和非饱和砂液化的物理过程，无论是否存在应力历史。过度固结引起的塑性体积应变在降低随后循环剪切的体积应变潜力方面不太有效，从而增强了其抗液化能力。该模型可以更好地理解导致饱和和非饱和砂液化的物理过程，无论是否存在应力历史。过度固结引起的塑性体积应变在降低随后循环剪切的体积应变潜力方面不太有效，从而增强了其抗液化能力。该模型可以更好地理解导致饱和和非饱和砂液化的物理过程，无论是否存在应力历史。