Scale Effects in Rock Failure

岩石破坏中的尺度效应

• 批准号: 0969784
• 负责人: Charles Fairhurst
• 金额: $ 25.07万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0969784&HistoricalAwards=false
• 关键词: Scale; Effects; Rock; Failure

With much of rock engineering involving large scale projects, the effects of scale - both spatial and temporal - on rock deformability and strength are central issues that are still not well understood. Joints and similar large-scale geological discontinuities are assumed to be the primary factor in reducing strength, but there is evidence to support the existence of a significant size effect even in "intact" rock. Recent developments in numerical modeling allow the interaction of fractures and the bridges of intact rock between them to be analyzed more realistically than in the past. The deep underground science and engineering laboratory (DUSEL) in Lead, South Dakota provides an excellent location to carry out fundamental research to evaluate and improve the numerical predictions.Large-scale in situ compression tests, in which pillars will be loaded to failure, are proposed for DUSEL Complete load-deformation curves will first be obtained in laboratory tests to assess the potential for brittle failure. Numerical predictions will be made of the pillar response to loading - using the Synthetic Rock Mass model - for all stages of pillar excavation. It is anticipated that the test specimens will range in diameter (or side width, if square) from about 2 m to 5 m, all with a final height to width ratio of 2:1. Knowledge transfer will be accomplished through a Grand Challenge, whereby research and consulting teams will be invited to submit blind predictions of the outcome of key stages of the in situ studies. This is intended to establish the state-of-the-art of predictive modeling, and to stimulate development. The educational mission will be to create and develop mechanisms and technologies that demonstrate, investigate, and enable the control of subsurface excavations through machine stiffness effects.

随着岩石工程涉及大规模的项目，规模的影响-空间和时间-对岩石变形性和强度的中心问题，仍然没有得到很好的理解。节理和类似的大型地质不连续性被认为是降低强度的主要因素，但有证据表明，即使在“完整”的岩石中，也存在显著的尺寸效应。最近的发展，在数值模拟允许的相互作用的裂缝和完整的岩石之间的桥梁进行分析比过去更现实。 位于南达科他州铅市的深层地下科学与工程实验室（DUSEL）为开展基础研究以评估和改进数值预测提供了一个极好的场所。DUSEL提出了大规模原位压缩试验，在该试验中，支柱将被加载至失效。 将采用综合岩体模型，对支柱开挖的所有阶段的支柱荷载响应进行数值预测。预计试样的直径（或边长，如果是正方形）范围为约2 m至5 m，最终高宽比均为2：1。知识转移将通过一项大挑战来完成，将邀请研究和咨询团队提交对实地研究关键阶段结果的盲测预测。这是为了建立最先进的预测建模，并刺激发展。 教育使命将是创建和开发的机制和技术，演示，调查，并通过机器刚度的影响，使地下开挖的控制。