Development of a Practical Soil Constitutive Model Suitable for the Design of Offshore Wind Turbine Foundations in Sand Considering Cyclic Loading

开发适用于考虑循环荷载的沙地海上风力发电机基础设计的实用土壤本构模型

• 批准号: 2440655
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2440655
• 关键词: Development; Practical; Soil; Constitutive; Model

Offshore wind turbines are subject to cycles of loading and unloading from their environment i.e. wind and waves. This cyclic loading can significantly weaken the foundations over time leading to a reduced loading capacity when compared with a static load of the same magnitude. Structures can fail due to the build-up of plastic strain in the soil over time through successive loading cycles. In addition, there are failure mechanisms caused by liquefaction (where pore water pressure builds up and soil friction decreases). Through laboratory experiments this project will seek to develop a constitutive model of sandy soil under cyclic loading. This will provide a better understanding of the behaviour of sandy soils with cyclic loads applied. Therefore, it should be possible to improve the design of offshore wind turbine foundations. This is of particular significance to the UK as much of the seabed surrounding Britain has at least partial presence of sandy layers, with some areas comprised almost entirely of sandy soil e.g. southern North Sea. Improvements in the design of offshore wind turbine foundations should lead to material and cost savings, helping to drive down the levelised cost of energy.The project methodology will be focussed around gathering results from cyclic triaxial tests. Triaxial tests are a standard industry test used to measure the mechanical response of a soil sample to prescribed stress and/or strain boundary conditions. The cyclic triaxial tests will apply computer controlled cyclic loads to a range of samples prepared with different initial densities and stress histories. The samples will be prepared in the lab, as opposed to testing cored samples from the field due to the tendency of sandy soils to break apart when loads are released. The results will be used to develop and calibrate a constitutive soil model, which will seek to improve the currently available models' shortcomings with respect to cyclic loading. Sandy soils are complex and therefore difficult to define fully with a constitutive model. Existing models prioritise modelling either static or cyclic loads at the expense of reducing accuracy with respect to the other load type. This project is novel in seeking to combine both cyclic and static loads into a single constitutive model.This project is part of the Wind and Marine Energy Systems and Structures (WAMESS) Centre for Doctoral Training and falls within the EPSRC Wind Power, Ground Engineering and Energy research areas. This project will be run in partnership with Fugro, making use of their large commercial soil testing laboratory in Wallingford (near Oxford). The project will work in tandem with another doctoral project of a similar aim, but more focussed on mathematical and computational modelling aspects.

海上风力涡轮机受到环境的加载和卸载的循环，即风和波浪。与相同大小的静态负载相比，这种环状载荷可以显着削弱基础，从而导致载荷能力降低。由于随着时间的流逝，通过连续的负载周期在土壤中积聚了塑性应变，结构可能会失败。此外，存在液化引起的故障机制（孔隙水压积聚，土壤摩擦减少）。通过实验室实验，该项目将寻求在循环载荷下开发出沙质土壤的本构模型。这将更好地了解使用循环负载的沙质土壤的行为。因此，应该有可能改善海上风力涡轮机基础的设计。这对英国尤其重要，因为英国周围的大部分海床至少存在沙质层的部分，有些地区几乎完全由沙质土壤组成，例如。北海南部。海上风力涡轮机基础设计的改进应导致材料和成本节省，有助于降低能源的水平化成本。项目方法将集中在收集环状三氧比赛测试结果上。三轴测试是一种标准行业测试，用于测量土壤样品对规定应力和/或应变边界条件的机械响应。环状三轴测试将将计算机控制的循环载荷应用于具有不同初始密度和应力历史的样品范围。这些样品将在实验室中制备，而不是由于沙质土壤释放载荷时易于分解的趋势，而不是测试田间的芯样品。结果将用于开发和校准组成型土壤模型，该模型将寻求改善有关环状载荷的当前模型的缺点。沙质土壤很复杂，因此很难用本构模型完全定义。现有模型优先考虑建模静态或循环载荷，而以降低其他负载类型的精度为代价。该项目是新颖的，试图将循环和静态载荷相结合到单个组成型模型中。该项目是风能和海洋能源系统和结构（Wamess）博士培训中心的一部分，并属于EPSRC风能，地面工程和能源研究领域。该项目将与Fugro合作运行，利用其在沃灵福德（牛津附近）的大型商业土壤测试实验室。该项目将与一个类似目标的另一个博士项目一致，但更着重于数学和计算建模方面。