Papers by Author: Shu Tao Liao

Abstract: The objective of this paper is to investigate the capabilities of the Impedance Log method in profiling the geometry of a pile along its length. The main idea of this method is to introduce a transient stress wave into the pile and then utilize the reflected signals to obtain the impedance profile of the pile. Any anomaly, which results in changes in impedance, would be detected by this method. In this study, four model piles with plan defects of weak zone or neck were constructed and tested using Seismic Echo, Impulse Response, and Impedance Log pile integrity nondestructive testing methods. Results of these tests show that interpretation of signals using the Impedance Log method is more straightforward than the other two methods. It is concluded that the Impedance Log technique is a tool with high potential for evaluating the integrity of piles.

Abstract: In order to increase the precision of a high speed dynamic autocollimator, which uses quadrate detector, we propose a new method to compensate the residual measuring errors. For this purpose, a multi-tooth rotary table with precision of 0.2 seconds of arc is used to calibrate the autocollimator. From the calibration data, a polynomial interpolation compensation algorithm is used. As a result, the measuring accuracy is increased to the order of 0.8 seconds of arc and the sampling speed is not affected.