Effect of Changing Plastic Work on Macroscopic Properties

引言“支撑液”通常用于桩和地下连续墙的施工，以防止土层不稳定和塌陷到开挖中，或防止水从渗透层渗入开挖中。最流行的支持流体是膨润土，其主要是蒙脱石粘土。聚合物支撑流体依赖于不同的机制来防止渗透到挖掘中存在的渗透性土层中，因此防止渗透到挖掘本身的支撑中。聚合物依赖于高粘度和施加在土壤颗粒上的显著粘滞阻力，以及在土壤表面形成膜的能力，以防止渗透到土壤的可渗透层中。对聚合物进行的研究（Jefferis & Lam，2013）表明，与更广泛使用的膨润土相比，使用聚合物在经济、性能和环境成本方面有更多的好处。目的和目标拟议的博士研究的目的是帮助和加速不可持续的膨润土向更有效的合成聚合物的过渡。这将涉及为现场技术人员开发测试技术，指导应用的设计规则，以及开发基础工程科学。由于工业的性质和支撑液的力学特性，开发新的现场测试非常重要。目前现场使用的测试程序快速且易于执行，但不准确。为支持流体的使用制定设计规则将确保这项研究将对工业产生直接影响。开发设计规则将集中在如何最有效地使用流体（在可持续性、成本和易用性方面）以及流体的使用可能如何影响孔中建造结构的规格。研究方法所提出的研究可能会被这些研究的结果所告知，尽管在对最近的文献进行有限的回顾之后，研究方法将分为三个部分：实验室测试、现场测试和理论分析。2在实验室阶段，研究的重点将是发展聚合物行为的知识和探索聚合物对周围土壤和环境的各种影响。有必要设计和开发定制设备，以进一步了解材料的力学和使用中表现出的性能。一种是观察材料的常规使用方式以及材料在实践中的表现，另一种是对当前实践进行修改，本研究的理论分析部分的重点将是解释实验结果，以帮助制定工业使用的规范。这可能涉及控制搅拌、泵送、桩钻孔等的速率。项目团队参与这项研究的团队将包括丹尼尔·麦克纳马拉（Daniel McNamara）作为哲学博士研究员，布莱恩·谢尔（Brian Sheil）博士作为主要主管，斯蒂芬·杰弗瑞斯（Stephan Jefferis）教授作为联合主管，奥雅纳（Arup）的克里斯·巴克（Chris Barker）作为项目的工业主管。& Lam，C.（2013年）。聚合物支撑液：岩土工程中创新流体的使用和误用。第18届土力学与岩土工程国际会议（18 th International Conference on Soil Mechanics and Geotechnical Engineering）3219-3222）。蓬茨新闻。

Introduction'Support fluids' are commonly used for the construction of piles and diaphragm walls to prevent instability and collapse of soil layers into the excavation or to prevent water from permeable layers seeping into the excavation. The most popular support fluid is bentonite which is a largely montmorillonite clay. Polymer support fluids rely on a different mechanism to prevent seepage into the permeable soil layers present in the excavation and therefore in the support of the excavation itself. Polymers rely on high viscosity and significant viscous drag which is exerted on the soil grains, as well as the ability to form a membrane at the soil face, to prevent seepage into the permeable layers of soil. Research (Jefferis & Lam, 2013) conducted on polymers has indicated that there are more benefits in the use of polymers compared with the more widely used bentonite; in terms of economy, performance, and environmental cost.Aims and ObjectivesThe aim of the proposed doctoral research will be to aid and accelerate the transition between unsustainable bentonites to more efficient synthetic polymers. This will involve developing testing techniques for site technicians, design rules to guide application, and to develop the underpinning engineering science. It is important to develop new testing for in-situ circumstances due to the nature of the industry and the mechanics of the support fluid. The current testing procedures used on site are quick and easy to carry out but are inaccurate. Developing design rules for the use of the support fluid will ensure that this research will have a direct impact on industry. Developing design rules will be focused on how the fluid can be used most effectively (in terms of sustainability, cost, and ease of use) and how the use of the fluid may affect the specification of the built structure in the bore.Research MethodologyThe proposed research may be informed by the results of these studies although, following a limited review of recent literature, the approach to the research will be split into three strands: laboratory testing, field testing, and theoretical analysis.During the laboratory phase of the research the focus will be on developing knowledge of polymer behaviour and exploring the various effects polymers have on the surrounding soil and environment. It will be necessary to design and develop bespoke equipment to further understanding of the mechanics of the materials and behaviour exhibited in use.The approach during the field testing will take two different courses; one being to observe the way in which the material is routinely used and how the material behaves in practice, the other being to implement modifications to current practice, informed by the laboratory tests and supported by introduction of on site testing of materials in use.The key focus of the theoretical analysis part of this research will be the interpretation of experimental results to aid development of specifications for use in industry. This could involve controlling rates for mixing, pumping, pile drilling etc.Project TeamThe team involved in this research will consist of Daniel McNamara as the DPhil researcher, Dr Brian Sheil as the main supervisor, Professor Stephan Jefferis as the co-supervisor, and Chris Barker, of Arup, as the industrial supervisor of the project.This project falls within the EPSRC Engineering research areaReferencesJefferis, S., & Lam, C. (2013). Polymer support fluids: use and misuse of innovative fluids in geotechnical works. 18th International Conference on Soil Mechanics and Geotechnical Engineering (pp. 3219-3222). Presse des Ponts.