Climate resilient earthwork design using green infrastructure

在英国，有数万英里长的植被基础设施斜坡，即支持铁路和公路的人造斜坡和削坡。仅铁路网就拥有52 000公顷土地，上面有近630万棵树。众所周知，土方工程在与植被相互作用时表现出较差的适用性，工程师倾向于将其视为负债，而不是将其视为国家资产。然而，维护良好的植被有可能提高边坡的稳定性，并产生积极的环境影响。据估计，未来20年将花费数亿英镑来管理植被，同时遵守安全和运营标准。作为一种工程材料，大气和土壤之间的相互作用直到最近才引起人们的极大兴趣。在干旱时期，植被密集的边坡会出现服务性问题，因为土壤会过度收缩。当降水进入土方工程的土壤中引起膨胀时，收缩不能完全恢复，因此收缩逐年累积。这种膨胀和收缩的循环预计将加剧，因为气候变化预测显示，极端降雨量将大幅增加，随后是长期的严重干旱。另一方面，在土方工程上建立植被可以通过其根系增加边坡的稳定性，降低土壤的渗透率，保护土壤免受侵蚀。为了正确理解和量化这些问题，并提出最佳绿化策略的解决方案，我们需要开发强大的模型，将从土壤到植被和大气的水分传输与土壤水力力学行为相结合。需要详细的数据来验证这些模型，这些模型在成功实施和验证后可用于为现代建筑以及现有土方工程的维护提供新一代岩土工程标准。该项目旨在将生态水文学、土壤和岩土工程建模联系起来，提高植被基础设施土方工程对气候变化的适应能力。该项目将按照以下任务组织：1借助CASE合作伙伴岩土观测，分析选定基础设施边坡的现场数据，并确定代表性案例研究; 2通过实地和实验室研究生成新数据（土壤机械和水力特性数据以及监测现有基础设施状况的实地数据）; 3开发一个独特的土壤-植物-大气模型，将岩土建模与所有必要的生态水文过程结合起来。模型开发将整合伦敦帝国理工学院水文和岩土工程部门之间的建模专业知识;4使用英国最新一代CMPI 6气候模型预测在气候变化下进行风险分析。

There are tens of thousands of miles of vegetated infrastructure slopes, i.e. man-made embankments and cut slopes which support railways and highways, in the UK. Network Rail alone owns 52,000 hectares of land on which there are nearly 6.3 million trees. As earthworks are known to demonstrate poor serviceability when interacting with vegetation, Engineers tend to perceive it as a liability rather than to appreciate it as a national asset. Well-maintained vegetation, however, has the potential to enhance slope stability and has undeniably positive environmental outcomes. It is estimated that hundreds of millions of pounds will be spent over the next 20 years to manage vegetation while complying with safety and operational standards. Interaction between atmosphere and soil as an engineering material has only recently attracted significant interest. Serviceability problems arise in densely vegetated slopes during dry periods, as the soil shrinks excessively. Shrinkage is not fully recovered when water from precipitation percolates into the earthworks' soils causing swelling, hence shrinkage accumulates year on year. This cycle of swelling and shrinkage is expected to intensify, as climate change projections show a substantial increase in rainfall extremes, followed by long periods of intensified drought. On the other hand, vegetation establishment on earthworks can increase slope stability via its roots, reduce the infiltration rate in the soils, protect the soil against erosion. To properly understand and quantify the problems as well as to propose solutions for best greening strategies, we need to develop robust models integrating water transport from the soils to vegetation and the atmosphere, and soil hydro-mechanical behaviour. Detailed data are needed to validate these models, which upon successful implementation and validation can be used to inform new-generation geotechnical engineering standards for modern construction as well as maintenance of existing earthworks. The project aims to bridge ecohydrological, soil and geotechnical modelling, with the scope of enhancing the resilience of vegetated infrastructure earthworks to climate change.The project will be organised in the following tasks:1 Analyse with the aid of the CASE partner Geotechnical Observations field data from selected infrastructure slopes and identify representative case studies;2 Generate new data though field and laboratory studies (data of soil mechanical and hydraulic properties and field data monitoring the behaviour of existing infrastructure);3 Develop a unique soil-plant-atmosphere model that integrates geotechnical modelling with all necessary ecohydrological processes. The model development will integrate modelling expertise between the Hydrology and Geotechnics sections at Imperial College London;4 Perform risk analysis under a changing climate using the last generation CMPI6 climate model projections for the UK.