Comprehensive Characterization of Unsaturated Soils using Advanced Photogrammetry and Novel Fiber Optic Sensors

该奖项旨在通过开发创新的测量方法和传感器来全面表征土壤行为，从而解决非饱和土力学领域的关键挑战。该项目的意义在于迫切需要准确的数据来推进非饱和土壤理论及其在关键基础设施、气候和能源相关问题上的应用。通过克服现有测量技术的局限性，该项目将为该领域的理论发展提供精确和全面的测试结果。本研究将介绍一种基于多相机的连续测量土样三轴试验过程中三维全场位移的摄影测量方法。这种方法相当于安装数千个高精度的非接触式位移传感器，将能够确定土样中任何点的应力状态。此外，新型光纤传感器将被开发出来，以极高的精度测量孔隙空气压力和孔隙水压力。这些直径与人类头发相似的传感器将首次为各种地质材料问题的耦合水-力学评估提供必要的数据。该项目的技术目标包括开发一种基于摄影测量的方法来测量三维全场土壤位移，以及用于精确测量孔隙空气和孔隙水压力的光纤传感器。本研究将涉及不同类型非饱和土在不同荷载条件下的表征，以获得全面准确的试验结果。这些数据，结合PI新颖的修正状态面方法，将解决非饱和土壤研究界的剩余争议点。该项目的智力优势在于它的跨学科性质，整合了电子、光纤、图像分析、计算机视觉、机器学习和多相介质力学方面的进步。该研究不仅推动了非饱和土理论的发展，而且使不排水试验成为本构建模的可行方法，大大缩短了试验时间。此外，所开发的测试方法和传感器将在饱和和非饱和土壤以及其他复杂的多相问题中得到应用。这项研究的广泛影响包括更安全和更具成本效益的基础设施设计，以及使用最先进的测试和建模方法培训下一代工程师和教育工作者。研究成果的传播将通过各种渠道进行，包括研究生和本科生培训、会议报告、研讨会和网络研讨会。与ASTM D18岩土委员会的合作将探索更新现有的三轴测试标准，确保研究成果得到更广泛的实施。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award aims to address critical challenges in the field of unsaturated soil mechanics by developing innovative measurement methods and sensors for comprehensive characterization of soil behavior. The project's significance lies in the urgent need for accurate data to advance unsaturated soil theory and its applications in critical infrastructure, climate, and energy-related issues. By overcoming the limitations of existing measurement techniques, the project will provide precise and comprehensive test results needed for theoretical developments in this field. This research will introduce a multi-camera based photogrammetric method for continuous measurement of 3D full-field displacement during triaxial testing of soil specimens. This method, equivalent to installing thousands of noncontact displacement sensors with high precision, will enable the determination of stress states at any points in the soil specimen. Additionally, novel fiber optic sensors will be developed to measure pore air pressure and pore water pressure with exceptional precision. These sensors, with diameters similar to a human hair, will provide data necessary for the coupled hydro-mechanical evaluation of various geo-materials problems for the first time.The project's technical objectives encompass the development of a photogrammetry-based method for measuring 3D full-field soil displacement, as well as fiber optic sensors for precise measurement of pore air and pore water pressures. This research will involve the characterization of different types of unsaturated soils under different loading conditions to generate comprehensive and accurate test results. These data, combined with the PI's novel modified state surface approach, will resolve remaining points of dispute within the unsaturated soils research community. The project's intellectual merits lie in its interdisciplinary nature, integrating advances in electronics, fiber optics, image analysis, computer vision, machine learning, and mechanics for multiphase media. The research will not only advance unsaturated soil theory but also enable the use of undrained tests for constitutive modeling, significantly reducing testing time. Furthermore, the developed testing methods and sensors will find application in both saturated and unsaturated soils, as well as other complex multiphase problems. The broader impacts of this research include safer and more cost-effective infrastructure design, as well as the training of the next generation of engineers and educators using state-of-the-art testing and modeling methods. The dissemination of research findings will occur through various channels, including graduate and undergraduate student training, conference presentations, workshops, and webinars. Collaboration with ASTM Committee D18 on Soil and Rock will explore updating existing standards for triaxial testing, ensuring the broader implementation of the research outcomes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.