Rheometrical techniques for the characterization of clay based suspensions relevant to geotechnical engineering

研究粘土-水悬浮液的流变特性在许多土木工程问题中具有重要意义。这些材料既存在于自然界中，例如在泥石流中，也被人类利用，在某些情况下通过添加添加剂（例如聚合物、水泥）进行适当的工程设计，用于各种应用（作为微隧道和管道掘进中的钻井和润滑流体，作为土壤改良的灌浆，作为隧道和挖掘中的稳定流体等）。迄今为止，对这些材料的研究在应用上是相当孤立的，而且往往依赖于经验检验和行为假设。拟议的研究旨在探索使用先进的流变学技术来研究岩土工程应用中“工程”粘土基悬浮液的流变特性。在本研究中，将使用最先进的流变仪进行粘度、蠕变和振荡测试，从而可以表征这些材料的流动和粘弹性特性，并以迄今为止从未在岩土工程中使用的方式深入了解其微观结构。这些性能将在不同的“体系”中进行研究：普通膨润土-水悬浮液（基本情况），添加三种添加剂（一种粘合剂和两种聚合物产品）的悬浮液，以及由钻井行业广泛使用的市售产品制备的悬浮液。这些“系统”适用于岩土工程的不同应用，具有不同的“性能”要求，因此有可能说明可以观察到的广泛的流变行为。还将进行更传统的测量（例如，使用传统粘度计和压力过滤试验进行流变测量），以便在岩土工程施工中使用的流体的设计和评估实践中提供基本行为和特性之间的联系，并为这些材料的更基于性能的设计奠定基础。就更广泛的影响而言，本研究的贡献可以概括为以下几点：-拟议的研究将以跨学科的方式解决工程粘土悬浮液的问题，并借鉴流体力学和土壤科学等其他学科的方法和知识。有了这种方法，以前没有在岩土工程中使用的测试和分析方法将应用于岩土“材料”。将所建立的实验和分析方法应用于教学，将有助于创新实验土力学（研究生）教学。-在设计和制造用于岩土工程应用的粘土基材料方面，与处于前沿的工业界合作，将确保所进行的研究有助于解决具有实际意义的问题，并将促进短期内将所学到的基本经验转移到实际领域。-与意大利都灵技术大学的合作协议将为与意大利最著名的技术机构之一发展持续的国际伙伴关系奠定基础，并将促进工作的更广泛传播。-综上所述，该项目将为参与研究的学生提供独特的发展机会。

Investigation of the rheological behavior of clay-water suspensions is important in many civil engineering problems. These materials are both present in nature, for example in mudflows, and are employed by man, appropriately engineered in some cases through the addition of additives (e.g. polymers, cement), in a variety of applications (as drilling and lubricating fluids in microtunneling and pipejacking, as grouts for soil improvement, as stabilizing fluids in tunnels and excavations, etc.). To date, investigations of these materials have been quite isolated by application and have often relied on empirical tests and on behavioral assumptions. The proposed research intends to explore the use of advanced rheometrical techniques for the rheological characterization of "engineered" clay-based suspensions employed in geotechnical applications. For this investigation use will be made of state of the art rheometers capable of performing viscosity, creep and oscillatory tests, which allow characterization of both the flow and the visco-elastic properties of these materials, and provide insight into their microstructure, in a manner so far never employed in geotechnical engineering. These properties will be investigated for different "systems": plain bentonite - water suspensions (base case), suspensions enhanced with three types of additives (one binder and two polymeric products), and suspensions prepared from commercially available products widely used in the drilling industry. These "systems", which pertain to different applications in geotechnical engineering, have different "performance" requirements and thus have the potential to illustrate the wide range in rheological behavior that can be observed.More traditional measurements (e.g. rheological measurements with traditional viscometers and pressure filtration tests) will also be performed to provide a link between fundamental behavior and properties used in practice for design and evaluation of fluids employed in geotechnical construction and to lay the basis for a more performance based design of these materials. In terms of broader impact the contributions of the study can be summarized in the following main points:- The proposed research will tackle the problem of engineered clay based suspensions with an interdisciplinary approach drawing on the methods and knowledge developed in other disciplines, such as fluid mechanics and soil science. With this approach, methods of testing and analysis previously not employed in geotechnical engineering will be applied to geotechnical "materials". Utilization in education of the experimental and analytical methods developed will contribute to innovate (graduate) teaching of experimental soil mechanics.- Collaboration with industry at the forefront in designing and manufacturing clay based materials for use in geotechnical applications will ensure that the research performed contributes to the solution of problems of practical significance, and will facilitate short term transfer of the fundamental lessons learned to the practical realm.- The agreement of collaboration with the Technical University of Torino in Italy will lay the basis for developing a continuous international partnership with one of the most renowned technical institution in Italy, and will promote broader dissemination of the work. - As a result of the above the project will provide unique development opportunities for the students involved in the research.