Shearing behaviour of fungal treated soils under low stresses

粒状土壤中的滑坡通常是由降雨引发的；这种现象和水渗透的潜在机制导致孔隙水压力增加（减少吸力），从而降低抗剪强度，这在世界范围内的天然山坡上都有很好的记录。在全球范围内，每年由降雨引发的致命山体滑坡多达350起；个别事件可能导致数千人死亡。在英国，在强降雨期间，每月记录的滑坡和滑坡多达80起。这些因素的主要影响是对运输网络造成严重破坏，并对经济和社会产生直接和间接影响。实施天然山坡补救措施的成本是巨大的，例如，2007年至2019年间，苏格兰运输部在苏格兰A83公路沿线的一个地点（休息和感恩）花费了1330万英镑。英国气候变化情景预测，随着冬季降水和降雨强度的增加，冬季更温暖、更潮湿，夏季更炎热、更干燥。我们不断变化的气候将进一步影响英国斜坡的稳定性，推动对其管理和维护的新方法的需求。缓解浅层边坡破坏的传统措施包括土钉、地锚、灌浆、边坡重塑、安装土工布和改善排水系统。这些传统的干预措施针对的是局部的不稳定，无法在大范围内有效部署。所使用的传统材料也含有高嵌碳（如钢铁和水泥）。此外，引入的“硬”工程材料的特性与周围的土壤之间往往存在差异，这可能导致局部侵蚀，或者实现不良接触（例如土壤和土工织物之间），这可能导致失败。显然，我们需要更低成本、更低碳、更可持续的解决方案。斯特拉斯克莱德大学的El Mountassir博士带领一个研究小组开发基于真菌的斜坡稳定解决方案。多细胞真菌以菌丝（由几丁质组成的管状结构）的形式生长，并在探索环境寻找营养物质时形成复杂的网络，分支并形成菌丝。本博士项目将研究真菌菌丝体对土壤剪切响应的影响。该研究将探讨不同真菌种类、真菌生长时间和真菌菌丝网络方向对土壤力学行为的影响。此外，在博士课程期间，将特别关注开发实验室协议，以便在与靠近斜坡表面（0-2m深度）的地面条件相关的低正应力下进行测试，传统的直接剪切设备不太适合。

Landslides in granular soils are often triggered by rainfall; this phenomenon and the underlying mechanism of water infiltration resulting in increased pore water pressure (reduced suction) and hence lower shear strength has been well documented for natural hillslopes worldwide. Globally, up to 350 fatal landslides are triggered by rainfall each year; individual events can cause thousands of fatalities. In the UK up to 80 landslides and slope failures are recorded per month during periods of heavy rainfall. The main impacts of these are major disruption to transport networks with direct and indirect economic and social impacts. The cost of implementing remedial measures for natural hillslopes is substantial, e.g. Transport Scotland spent £13.3M at a single site (Rest & Be Thankful) along the A83 in Scotland between 2007-2019. UK climate change scenarios predict warmer, wetter winters and hotter, drier summers with increases in winter precipitation and rainfall intensity. Our changing climate will further impact on the stability of slopes in the UK, driving the need for novel approaches for their management and maintenance. Traditional measures to mitigate shallow slope failures include soil nailing, ground anchors, grouting, slope reprofiling, installing geotextiles and improving drainage. These traditional interventions target localised instabilities and cannot be deployed effectively over large areas. The conventional materials used also have a high embedded carbon (e.g. steel and cement). Further, there is often a contrast between the properties of the 'hard' engineering materials introduced and the surrounding soil which can result in local erosion, or poor contact is achieved (e.g. between soil and geotextiles) which can contribute to failures. There is a clear need for lower cost, lower carbon, more sustainable solutions. Dr El Mountassir at the University of Strathclyde is leading a research group developing fungal-based solutions for stabilising slopes. Multi-cellular fungi grow as hyphae (tubular structures consisting of chitin), and form complex networks as they explore their environment in search of nutrients, branching out and forming mycelium. This PhD project will investigate the influence of fungal mycelium on the shearing response of soils. The study will investigate the influence of different fungal species, fungal growth duration and orientation of fungal hyphal networks on soil mechanical behaviour. Furthermore, special attention will be paid during the PhD programme to developing laboratory protocols to enable testing at low normal stresses relevant to the ground conditions close to the slope surface (0-2m depth), which traditional direct shear equipment is not well-suited to.