Direct Measurement of Strain-Rate Dependent Constitutive Relations for the Compression of Clay

CMS-9622644 题目：“粘土压缩的应变率相关本构关系的直接测量” 共同主要研究者：Gerald A. Leonards和帕特里克J.福克斯，土木工程系，普渡大学 拟议的研究计划的目的是提供明确的实验数据，以解决长期存在的问题，应变率的影响过程中的固结粘土。 新的实验技术将被用于测量固结过程中和固结完成后的压缩性的时间相关和时间无关分量，而不需要对测试结果进行分析解释。 已知对应变率效应敏感的未扰动土壤将使用以下设备进行测试：1）经过特殊处理的固定环固结仪，用于降低侧壁摩擦; 2）改良的KO-三轴单元，用于在零侧摩擦条件下提供基本上一维应变，并使用流量泵体积控制系统。 孔隙比和有效应力的局部值将被直接测量。 应变率的大范围将通过测试不同厚度的样品来研究。 将使用冗余实验来确定结果不存在偏差，因为在一种情况下，结果与零侧摩擦存在微小偏差，而在另一种情况下，结果与零侧向应变存在微小偏差。 通过直接测量获得的基本本构关系，增量加载试验中孔隙水压力消散的预测，以及恒定应变率（CRS）试验中孔隙水压力的建立，将与使用块体样品的重复样品进行比较。 这项研究的结果将有一个巩固的概念是如何教，并在实践中如何应用的根本影响。

CMS-9622644 Title: "Direct Measurement of Strain-Rate Dependent Constitutive Relations for the Compression of Clay" co-PI's: Gerald A. Leonards and Patrick J. Fox, Department of Civil Engineering, Purdue University The objective of the proposed research program is to provide definitive experimental data to resolve long-standing issues of strain rate effects during the process of consolidation in clay. Novel experimental techniques will be applied to measure the time-dependent and time- independent components of compressibility both during and after the consolidation process is completed, without the need for analytical interpretation of the test results. Undisturbed soils, known to be sensitive to strain rate effects, will be tested using: 1) a fixed-ring consolidometer specially treated for low sidewall friction, and 2) a Ko-triaxial cell modified to provide essentially one-dimensional strain under conditions of zero side friction, using a flow-pump volume control system. Local values of void ratio and effective stress will be measured directly. Large ranges in strain rate will be investigated by testing samples of different thickness. Redundant experiments will be used to establish that the results are free from bias due to minor departures from zero side friction in one case, and from zero lateral strain in the other. With the basic constitutive relations obtained from direct measurement, predictions of pore water pressure dissipation in incremental loading tests, and build up of pore water pressures in constant rate of strain (CRS) tests, will be compared with those using replicate specimens from block samples. The results of this study will have a fundamental bearing on how consolidation concepts are taught, and on how they are applied in practice.