CT- and multi-monitoring ready thermo-frozen-hydro-mechanical 3D loading system

CT 和多监测就绪热冷冻水机械 3D 加载系统

• 批准号: 500412763
• 金额: --
• 依托单位: Christian-Albrechts-Universität zu Kiel
• 依托单位国家: 德国
• 项目类别: Major Research Instrumentation
• 财政年份: 2022
• 资助国家: 德国
• 起止时间: 2021-12-31 至 无数据
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/500412763?language=en
• 关键词: CT; multi; monitoring; ready; thermo

In view of the upcoming climate change, the analysis of frozen soil materials is of fundamental importance for the adaptation or mitigation in urban areas as well as for the understanding of occurring geological phenomena. The currently existing permafrost soils are essential in securing the organic carbons encapsulated therein and in stabilizing the existing soil structures, such as constantly and seasonally frozen soils (cryosols) in the cryosphere, embankments, foundations, due to the high rigidity of the subsoil. Here, the basic understanding of changing the coupled cryo-hydro-mechanical soil properties must be improved, so that in addition to the changed chemical, biological processes through the thawing or the transition of the cyclical, alternating thawing / freezing of upper cryosols, the resulting hydraulic, mechanical Changes such as weathering, loss of stiffness and strength, frost-related mixing and erosion can be assessed and modeled. Changes in the cryopedogenic processes such as ice segregation, ice accumulation and cryometamorphosis under alternating thawing / freezing are also unknown.In the adaptation of urban life and the mitigation of increasing urban heat hotspots, the cooling of infrastructures becomes more important. To do this, urban ice stores must be built on a geological scale. Initial research on this is already in progress. From a structural engineering point of view, freezing processes with the load-bearing capacity or protection against failure are known. Cyclical freezing processes, such as those required for the use of ice storages, are completely unknown in terms of their effects. The effects of cyclical freeze-thaw hysteresis on the volumetric pore space and structure changes, in the Atterberg limits or mechanical strength and compressibility degradations have hardly been analyzed and have significant effects on sediments with a larger proportion of fine particles. Secure geomechanical forecasts for these sediments for cyclical freeze-thaw cycles are not yet possible.For the modeling of the cyclic cryo-hydro-mechanical material behavior of frozen soils, a large number of different experimental tests are to be carried out, for which a previously non-existent laboratory device is to be purchased. For the experimental 3D analyzes of the soil samples, a 3-dimensional pressure system for cyclical cryo-thermo-hydro-mechanical loading is to be acquired, which in addition to the cyclical freezing / thawing, the additional installation of further monitoring devices (digital cameras for particle image Velocity, thermography cameras, laser technology, μCT's, radar, etc.) are allowed directly on the sample and during the test process, so that local changes in the structure can be recorded in high resolution as tomography or surface plot and transferred to the modeling.

鉴于即将到来的气候变化，对冻土材料的分析对于城市地区的适应或缓解以及对发生的地质现象的理解都是至关重要的。由于下层土壤的高度刚性，目前存在的永久冻土对于确保包裹在其中的有机碳的安全和稳定现有的土壤结构至关重要，例如冰冻圈、路堤、地基中的恒定和季节性冻结的土壤(冻土)。在这里，必须提高对改变冷冻-水-力学耦合土壤性质的基本认识，以便除了通过上层冻土的循环、交替解冻/冻结的解冻或转变而改变的化学和生物过程之外，还可以评估和模拟由此产生的水力和力学变化，如风化、硬度和强度的损失、与霜冻有关的混合和侵蚀。在冰冻/解冻交替作用下，冰的分离、积聚和变形等低温过程的变化也是未知的。在适应城市生活和缓解日益增加的城市热点中，基础设施的冷却变得更加重要。要做到这一点，城市冰库必须建立在地质规模上。对此的初步研究已经在进行中。从结构工程的角度来看，具有承载能力或防止破坏的冻结过程是已知的。就其影响而言，周期性的冻结过程，如使用冰库所需的过程，是完全未知的。在Atterberg极限范围内，周期性冻融滞后对体积孔隙空间和结构变化的影响，以及对机械强度和压缩性降解的影响几乎没有分析过，并且对细颗粒比例较大的沉积物有显著影响。目前还不可能对这些沉积物进行周期性冻融循环的地质力学预测。为了对冻土的循环冷冻-水-力学材料行为进行建模，需要进行大量不同的实验测试，为此需要购买以前不存在的实验室设备。对于土壤样品的实验三维分析，需要获得一个用于循环冷冻-热-水-机械加载的三维压力系统，除了循环冻结/解冻外，还需要额外安装更多的监测设备(颗粒图像速度的数码相机、热像仪、激光技术、μCT、雷达等)。允许直接在样品上和在测试过程中，因此结构中的局部变化可以高分辨率地记录为层析或表面图，并传输到建模。