Strain Measurement of Soil Specimen in Triaxial Test with Digital Image Processing Technology

摘要

There are some methods to measure deformation of soil specimen In triaxial tests. The purpose of this paper is to measure the deformation of soil specimen at sub-pixel accuracy with digital image processing technology, We adopt CMOS camera to capture images. In order to measure the deformation of soil specimen, we print some chessboard mark on the membrane of soil specimen. During the test, results can be seen at any time so that we can be informed in time when accidents occur. We use CMOS camera to decrease the test cost and it is convenient because it is connected to computer by USB interface. Furthermore, CMOS camera supports random pixel access, which allows direct access to the requested sub-image. In this paper, we apply corner detector technology to detect many points both in axial and radial directions at sub-pixel accuracy. Cross points are located in high accuracy about 0.04 pixel in radial and axial direction.