Collaborative Research: Further Investigation of the Onset and Evolution of Compaction and Dilation Bands

本项目是压缩和膨胀带形成的实验和理论研究的继续，研究了与局部带形成条件有关的几个关键问题。具体的项目活动包括：1)研究应力集中对压实带起始/演化的影响，2)研究层理和各向异性对压实带形成的影响，3)检查阿兹特克砂岩中的局部化行为并与最新的现场结果进行比较，4)研究三轴拉伸下多孔砂岩中膨胀带的形成，以及5)开发和评估基于两种损伤机制的本构模型来描述观察到的微观损伤机制。这项实验工作与公布的数据一起，提供了一组关于多孔砂岩的具有竞争力的力学和微观结构数据。进一步的理论分析考察了本构模型和应力状态对局部化条件的影响，并包括了实验得出的材料参数约束。通过综合实验和理论结果，外推了一个模型，以预测不同应力状态和加载路径下的地壳破坏模式和局部化发展。

AbstractThis project, a continuation of experimental and theoretical investigation of compaction and dilation band formation, examines several critical questions regarding conditions for localized band formation. Specific project activities include: 1) investigation of the influence of stress concentration on compaction band initiation/evolution, 2) investigation of the influence of bedding and anisotropy on compaction band formation, 3) examination of the localization behavior in Aztec sandstone and comparison with recent field findings, 4) investigation of dilation band formation in porous sandstone under triaxial extension, and 5) development and evaluation of two-damage mechanism based constitutive models to represent observed microstructural damage mechanisms. The experimental work, together with published data, provides a compete set of mechanical and microstructural data on porous sandstones. Further theoretical analyses examine the influence of constitutive models and stress state on localization conditions, and include incorporation of experimentally derived material parameter constraints. By synthesizing experimental and theoretical results, a model is extrapolated to predict failure modes and localization development in crustal settings for different stress states and loading paths.