三轴试验是研究土体强度与变形特性的重要测试手段,试验过程中需要测量试样的体积和变形。提出了一个基于GeoPIV-RG技术的方法,融合多光学介质摄影测量技术实时测量三轴试样的全局变形。该方法通过系统设置、照片拍摄、多相机摄影测量分析、GeoPIV-RG二维点云生成、三维点云生成、点云拼接、端部截断、位移与应变场计算等步骤实现三轴试样体积与全局变形的实时、精细测量。为验证该测量方法的可行性与精度,开展了一个钢柱和多个土样在不同条件下的三轴试验。钢柱试验结果表明所提出的方法能实现试样整体体积的精确测量(误差为0.36%);粉土试验结果表明该方法可实现试样全局变形的精细、高效量测。GeoPIV-RG技术的引入实现了三轴试样表面不同密度点云的高效提取,有效弥补了多光学介质摄影测量方法的不足;同时,多光学介质摄影测量技术将GeoPIV-RG技术的应用从二维、单光学介质推广到了三维、多光学介质。所提出的方法为研究土体在三轴试验过程中的变形特性提供了一个高效、可靠的工具。
Abstract
Triaxial test is widely utilized for characterizing soil mechanical behavior, during which soil volume and deformation is required to be measured. This paper introduces a real-time and precise measurement method for soil volume and deformation during triaxial testing, achieved through a GeoPIV-RG based approach using multi-media photogrammetry. This measurement process encompasses system setup, image capturing, multi-camera photogrammetric analysis, GeoPIV-RG-based 2D point cloud generation, 3D point cloud generation, point cloud stitching, end cut, mesh generation, and interpolation, followed by displacement and strain field calculation. To validate the accuracy and feasibility of this method, triaxial tests were conducted on steel cylinder and silt specimens. Test on steel cylinder confirmed that the proposed method accomplished soil volume measurement with an error of only 0.36%, while triaxial test on silt specimen demonstrated the method's capability in real-time and high-resolution full-field measurement of soil deformation. GeoPIV-RG enables the efficient extraction of point clouds on specimen surfaces and overcomes the limitations of the multi-media photogrammetric method. Moreover, the multi-media photogrammetric method broadens the application of GeoPIV-RG from two-dimensional and single-medium conditions to three-dimensional and multi-media settings. Overall, the proposed method presents an efficient and reliable solution for measuring soil deformation during triaxial testing.
关键词
GeoPIV-RG /
摄影测量 /
三轴试验试样 /
试样体积 /
全局变形
Key words
GeoPIV-RG /
photogrammetry /
triaxial test /
sample volume /
full-field deformation
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基金
国家自然科学基金青年项目(51709088)
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