Collapse, Steady State Concept, and Liquefaction of Granular Soils

该研究计划涉及基础 理解行为的概念 饱和的粒状物质（通常是沙子） 用水（地下水位以下）时 受到强烈的地面运动 是由地震引起的 下 在这些条件下， 潜在的“剪切”，即失去剪切力 强度和承受大变形， 导致建筑物地基损坏， 隧道和管道建在或通过 通过这种液化的土壤。 这种现象 与饱和松散体的响应有关 沙子充分变形，导致流动 公里. 一 毁灭性的山体滑坡就是一个例子 滑梯 稳定状态（流量）之间的关系 滑动）和循环（地震）行为是 通过基础实验 问题研究 需要调查的一个关键因素是 沙的结构性塌陷概念 织物. “崩溃”的概念是 与此相关的事实是， 收缩砂是亚稳的。 中 膨胀的骨骼，小的剪切应变可能 足以产生一个突然的 颗粒的重排， 相邻接触点之间的丢失 粮食，伴随着大量增加， 孔隙水压力 因此，剪切 沙子的强度降低到一个小的 价值和沙子变得容易受到 大变形 这一调查结果是预料之中的 促进更好地了解 液化现象和相关的 不稳定性，并导致改善 有能力预测其发生。

This research program addresses fundamental concepts for understanding the behavior of granular material (usually sand) saturated with water (below the ground water table) when subjected to the strong ground motions resulting from earthquake shaking. Under these conditions, such soils have the potential to "liquefy", that is to lose shear strength and undergo large deformations, resulting in damage to building foundations, tunnels and pipelines built on or passing through such liquefied soil. This phenomenon is related to the response of saturated loose sands strained sufficiently to result in flow slides. A devastating landslides is an example of such a flowslide. The relation between the steady state (flow slide) and the cyclic (earthquake) behavior is being addressed by fundamental experimental studies. A key element to be investigated is the concept of structural collapse of the sand fabric. The concept of "collapse" is associated with the fact that the structure of contractive sands is metastable. In a collapsive skeleton, small shear strains may be sufficient to produce a sudden rearrangement of grains with an associated loss of contact points between neighboring grains, accompanied by a large increase in pore water pressure. Consequently, the shear strength of the sand is reduced to a small value and the sand becomes susceptible to large deformations. The results of this investigation are expected to contribute to an improved understanding of liquefaction phenomena and associated instabilities, and to result in an improved ability to predict their occurrence.