A New Experimental Approach Toward a Unified Theory of Time-Dependent Consolidation

9800318 Sheahan，《一种新的实验方法来实现时间相关固结统一理论》，这项研究涉及一种创新的实验方法来帮助解决岩土工程中的一个基本问题：固结过程中随时间变化的蠕变变形的作用。原有的细粒土固结理论不能预测恒定有效应力水平下蠕变变形的影响。这导致了重大的实际问题，包括难以根据实验室试验预测现场固结沉降。这也导致了对固结过程中蠕变性质的研究和争论。一种假设预测蠕变变形的影响，直到所有加载引起的孔隙水压力消散；另一种假设包括整个固结过程中的蠕变。有大量的数据和杰出的研究人员支持这两种理论，但它们之间几乎没有一致之处。本研究将探讨巩固模型的有效性，该模型可以潜在地统一两个假设，并解释两组明显冲突的数据。本研究的目的不是为了证明其中一个假设，而是为了测量每个固结成分（由于孔隙压力耗散和由于蠕变）对整体行为的贡献。这项研究将由东北大学和马萨诸塞大学阿姆赫斯特分校合作进行。马萨诸塞大学-阿默斯特分校的合作伙伴将获得四种天然土壤的高质量块样，每种土都有自己的特殊结构，并将进行短期和长期的常规增量加载试验，以评估蠕变行为和常规固结参数。在东北大学，一种计算机自动化的、专门测量的固结单元是在先前的NSF奖励下开发的。该装置将用于执行控制梯度测试，并由中试样孔隙压力探头提供反馈。＊＊＊

9800318 Sheahan "A New Experimental Approach Toward a Unified Theory of Time- Dependent Consolidation" This research involves an innovative experimental approach to help resolve a fundamental issue in geotechnical engineering: the role of time-dependent creep deformations during consolidation. The original consolidation theory for fine-grained soils cannot predict the influence of creep deformations that occur under constant effective stress levels. This has led to significant practical problems, including difficulty in predicting field consolidation settlements based on laboratory tests. It has also led to research and debate on the nature of creep during consolidation. One hypothesis predicts no influence of creep deformations until after all loading-induced pore water pressures are dissipated; the other hypothesis includes creep throughout the consolidation process. There are substantial data and prominent researchers supporting each of the two theories, but little agreement between them. This research will investigate the validity of a consolidation model that can potentially unify the two hypotheses and explain both sets of apparently conflicting data. This research is not aimed at proving one of the hypotheses, but toward measuring the contribution of each consolidation component (due to pore pressure dissipation and due to creep) to the overall behavior. The research will be executed through a partnership between Northeastern University and the University of Massachusetts- Amherst. The UMASS- Amherst partner will obtain high quality block samples of four natural soils, each with its own particular structure, and will perform short- and long- term conventional, incrementally loaded tests to evaluate creep behavior and conventional consolidation parameters. At Northeastern, a computer-automated, specially inst rumented consolidation cell was developed under a prior NSF award. This device will be used to perform controlled gradient tests with feedback provided by mid-specimen pore pressure probes. ***