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应用基于亚像素角点识别的计算机图像处理技术,提出并实现了一种土工三轴试验试样全表面变形观测的图像测量方法。通过一台CMOS摄像机,借助放置于改制压力室中的平面反光镜,实现了对试样全表面变形的实时测量。在此基础上,对原始数据进行了畸变修正及像素当量归一化,并通过引入相邻时间间隔每个计算邻域内试样等向膨胀的计算假定,求得了试样全表面变形场。最后,以饱和砂土三轴排水剪切试验为例,探讨了全表面变形场在分析试样局部化变形中的应用。
A computer image processing technique based on the sub-pixel corner recognition is proposed and an image measurement method of full surface deformation observation of a geotechnical triaxial test specimen is proposed and implemented. Through a CMOS camera, with the help of a plane reflector placed in a reforming pressure chamber, real-time measurement of the total surface deformation of the specimen is achieved. On this basis, the original data were corrected for distortion and normalized by pixel equivalence. The total surface deformation field of the sample was obtained by introducing the assumption of isometric expansion of each sample in the adjacent time interval. Finally, taking the triaxial drainage shear test of saturated sand as an example, the application of the total surface deformation field to analyze the localized deformation of the sample is discussed.