中文摘要：

作为一种数字图像测量方法，亚像素角点检测能够在数字图像中可以发现角点的亚像素精度的位置（简称亚像素角点检测方法）。在土工三轴试验中应用该方法使得试样的变形测量更加简便。通过使用高精度标定板，对该数字图像测量方法进行了精度分析，结果表明亚像素角点检测方法的轴向和径向测量的标准差都达到了0.02个像素，相对测量精度达到10^-4数量级。在三轴压缩试验条件下，同时使用高精度位移传感器和该测量方法对小变形的干性试样进行了变形测量，证明亚像素角点检测方法对试样变形的测量结果是精确可靠的。

英文摘要：

As a digital image measurement method, the sub-pixel accurate location of a corner can be found in digital image by sub-pixel accurate corner locator. The purpose of this paper is to introduce digital image measurement method for measuring triaxial specimen deformation based on sub-pixel accurate corner locator. The distortion target of high precision is used to analyze the precision of the method. The results show that both axial and radial measurement precisions achieve 0.02 pixel and the magnitudes of relative measurement precision achieve 10^-4. The high precision distance transducer and sub-pixel accurate corner locator method are simultaneity used to measure the small deformation of dry-specimen in triaxial compression test; and the accuracy and reliability of the method are proved.