Martian Rammed Earth

火星夯土

• 批准号: EP/X018504/1
• 负责人: Paul Hughes
• 金额: $ 25.4万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FX018504%2F1
• 关键词: Martian; Rammed; Earth

Extended human exploration (and ultimately, settlement) on Mars has long been an ambition, and with the rise of private space companies and increasing numbers of successful data-retrieval missions, what was once a theoretical prospect is now rapidly becoming a plausible reality. For this to be realised, shelter and infrastructure will need to be established, requiring construction materials for structures exposed to the Martian atmosphere as well as within habitable environments.Naturally, transporting bulk construction materials from Earth is unfeasible and so a number of potential solutions have been suggested, ranging from inflatable habitats to below surface structures. In-situ resource utilisation has gained considerable traction and there has been research into various forms of this such as Martian concrete and 3D printed regolith, although these require additives and/or energy intensive processes.A more ideal solution to this space-age problem may, in fact, be one of the most ancient forms of construction: rammed earth. Rammed earth has seen something of a resurgence as a sustainable building material and interest in understanding the sources of its strength and durability has been renewed. In particular, recent studies have modelled rammed earth as an unsaturated soil, pointing to a "pore suction" that develops as rammed earth dries out and equilibrates with its surrounding environment. This is similar to the way that adding just a small amount of water to dry sand allows sandcastles to be built at the beach. Sadly, no one has been able to bring samples of Martian regolith (soil) back to Earth but thanks to exploratory probes a good understanding of the composition of the material that covers the Martian surface exists. This information has been used to make replica, or simulant, Martian regolith from materials existing on Earth. These simulants have been vital for testing the prototype of the Perseverance rover that NASA landed on Mars in 2020. Some previous research has been conducted into the potential of rammed earth Martian regolith using regolith simulants, but this previous work did not investigate the effects of the Martian atmosphere and gravity on the material produced. The way that rammed earth on Earth reaches equilibrium with the environment in which it is situated in is crucial to the strength it exhibits and the same will apply on Mars. It is therefore vital to test rammed earth under the prevailing conditions to understand if this technique is viable for building Martian infrastructure. This project will therefore investigate how rammed earth can be made on Mars and what its likely mechanical properties will be in-situ. This will be achieved by testing samples of simulated Martian soil, compressed into blocks and subjected to Martian atmospheric and gravity conditions. Doing so is very challenging as the Martian atmosphere is very low pressure (around 1-2% of the air pressure on Earth), the maximum temperature is 20 degrees Celsius (but can drop to more than 50 degrees below freezing) and the air is 95% carbon dioxide. Harder to simulate still is the low gravity on Mars (around one third of that on Earth). This project will simulate the atmospheric pressure, temperature and air composition in atmospheric chambers, within which the material properties will be determined. Martian gravity conditions can't be replicated exactly but tests will be conducted at high levels of gravity in a geotechnical centrifuge and at microgravity by doing experiments in free-fall and this information will be used to extrapolate the material performance on Mars. This project will establish the feasibility and fundamental tools to build using rammed earth on Mars and will lay a foundation for future research and development work investigating optimal structural forms and construction techniques for the creation of Martian structures and infrastructure.

长期以来，人类在火星上的探索（并最终定居）一直是一个雄心勃勃的目标，随着私人太空公司的崛起和越来越多成功的数据检索任务，曾经的理论前景现在正迅速成为一个看似合理的现实。为了实现这一目标，需要建立庇护所和基础设施，需要暴露在火星大气和可居住环境中的建筑材料。当然，从地球运输散装建筑材料是不可行的，因此提出了许多潜在的解决方案，从充气栖息地到地下结构。就地资源利用已经获得了相当大的吸引力，并且已经对各种形式的资源利用进行了研究，例如火星混凝土和3D打印风化层，尽管这些都需要添加剂和/或能源密集型工艺。事实上，对于这个太空时代的问题，一个更理想的解决方案可能是最古老的建筑形式之一：夯土。夯土作为一种可持续的建筑材料已经出现了复苏，人们对夯土强度和耐久性的来源的了解已经重新燃起了兴趣。特别是，最近的研究将夯土建模为非饱和土，指出当夯土干燥并与周围环境平衡时，会产生“孔隙吸力”。这类似于在干燥的沙子中加入少量的水，就可以在海滩上建造沙堡。遗憾的是，没有人能够将火星风化层（土壤）的样本带回地球，但由于探索探测器，人们对覆盖火星表面的物质的组成有了很好的了解。这些信息已被用于从地球上现有的材料中复制或模拟火星风化层。这些模拟装置对于测试NASA在2020年登陆火星的毅力号探测器的原型至关重要。以前的一些研究已经使用模拟风化层来研究夯实地球火星风化层的潜力，但是以前的工作并没有研究火星大气和重力对产生的物质的影响。夯土在地球上与它所处的环境达到平衡的方式对它所展示的强度至关重要，同样也适用于火星。因此，在现有条件下测试夯土是至关重要的，以了解这种技术是否适用于建造火星基础设施。因此，该项目将研究如何在火星上制造夯土，以及它在火星上可能具有的机械特性。这将通过测试模拟火星土壤的样本来实现，这些样本被压缩成块，并受到火星大气和重力条件的影响。这样做非常具有挑战性，因为火星大气压力非常低（约为地球气压的1-2%），最高温度为20摄氏度（但可以降至冰点以下50多度），空气中95%是二氧化碳。更难模拟的是火星上的低重力（大约是地球的三分之一）。该项目将模拟大气室中的大气压力、温度和空气成分，在此环境中确定材料的性能。火星上的重力条件不能完全复制，但测试将在高重力的土工离心机中进行，并在微重力下进行自由落体实验，这些信息将用于推断火星上的材料性能。该项目将确定在火星上使用夯土建造的可行性和基本工具，并将为未来的研究和开发工作奠定基础，研究火星结构和基础设施的最佳结构形式和施工技术。