Effects of Fabric Evolution on Liquefaction Resistance of Sands

沙子的结构（即物理结构）， 老化的影响， 在确定必要的应力方面起着重要作用 在地震荷载下引发液化。 最近 观察表明，砂组构的变化， 在现场测量，可能会导致快速初始增益， 但是动态载荷，例如 由地震引起的，导致这种硬度降低。 这 导致砂土液化的显著波动 抵抗时间。 有可能是身体和 化学机制可能有助于这些年龄相关的 抗液化性的变化。 本研究项目的基本目的是调查 实验室是否有益老化对土壤结构的影响 可以被相对低水平的循环应变破坏， 从而模拟地震的影响， 比“设计地震”更小，但更频繁， a given给定site地点. 我们的目标是调查地震- 诱导时间对砂组构影响的可逆性， 从而得出结论，这是否是一个实际问题， 在评估给定的液化潜力时， 绝佳的价钱 如果事实证明是这样，它将带来 质疑基于流量计的设计 方法目前正在应用，并将进一步建议， 保守的设计方法可能是基于 抗液化潜力评价 在实验室中，在新鲜沉积状态下的沙子。

The fabric (that is, the physical structure) of sand, and the effect of aging, play a fundamental role in determining the stresses necessary to trigger liquefaction under earthquake loading. Recent observations indicate that changes in sand fabric, as measured in the field, may result in a rapid initial gain in stiffness due to aging, but that dynamic loads, such as those induced by earthquakes, cause this stiffness to degrade. This results in significant fluctuations of the sand liquefaction resistance with time. It is possible that both physical and chemical mechanisms may contribute to these age-related changes in liquefaction resistance. The basic intent of this research project is to investigate in the laboratory whether beneficial ageing effects on soil fabric can be destroyed by relatively low levels of cyclic strain, thereby simulating the effects of earthquakes which are smaller, but more frequent, than the "design earthquake" for a given site. The goal is to investigate the earthquake- induced reversibility of the effects of time on sand fabric, thereby concluding whether it is a matter of practical concern in evaluating the liquefaction potential of a given site. If this turns out to be the case, it will bring into question the way in which penetrometer-based design methods are currently applied, and will further suggest that a conservative design approach may be to base the liquefaction potential evaluation on the resistance of the sand in a freshly-deposited state in the laboratory.