Using seismoacoustic defectoscopy to assess the continuity of piles

Introduction. The authors present the results of pile continuity studies conducted using seismoacoustic defectoscopy. Tests were conducted in the Rostov region and Moscow. Reflectograms of tested piles, as well as the subsequent interpretation and confirmation of the design length and continuity of the pile shaft are provided. Materials and methods. The research results were obtained using Spektr 4.3, whose operating principle is based on the theory of elastic wave propagation. This device is used for the recording of the pile response to external impacts with the preset pulse parameters. The signal is recorded by means of an accelerometer sensor, connected to a special computer with the software for the digitization and interpretation of incoming information. Data processing results are presented in the form of computer graphic images (reflectograms), which show the pile length, continuity, damages (if any) and their location. Results. The dependence between soil homogeneity and signal purity has been identified. At the interface between two types of soils that are different in density, the sound wave was reflected and partially passed further, creating characteristic peaks of false defects. To eliminate false defects, studies of layered soils are necessary. Conclusions. The results confirm the effect of the soil homogeneity on signal purity. The higher the heterogeneity of the soil structure, the bigger the number of false peaks that the reflectogram demonstrates. A prerequisite for the correct interpretation of the results of pile continuity testing is the study of the geological section and preliminary instrumental identification of the ultrasound propagation velocity for each individual pile.