Abstract: Borehole camera technology, which uses the image acquisition and processing technology, can provide the direct observation inside the borehole. The principal of the camera is mainly based on the optical theories. This technology has been successfully applied to the geotechnical engineering insitu testing and investigations. It can also provide both quantitative and qualitative analysis of the underground images. In the application of this device, without considering the differences between the human operation and the other unconventional measurement errors, the results differences among the various possible influence factors are mainly categorized in two aspects: the diameter of the borehole for the cast insitu piles and the length of the defect. In this paper, a simulation test for the measuring error of the borehole optical imaging is designed by considering the differences between the various testing items. By comparing the results of the test to the simulated defects, it is found that there is a deviation between the test data offered by the borehole optical imager and the true value and the deviation is mainly composed of the systematic error and the random error. Last, the correlation formula of the measuring error (deviation coefficient) for the borehole diameter and the length of the hole is established using the multiple linear regression method.

Key words: Borehole Camera, Optical Imaging Device, Measurement Errors