关键词: 改进型数字图像匹配(digital image correlation,DIC)技术, 细观测量, 土体竖向位移, 桩-土界面

Abstract:

Recently, application of the digital image correlation (DIC) technique in geotechnical engineering is used widely. In model tests, the DIC technique can be used to measure soil displacement around a pile during pile penetration. However, measuring displacement on soil-pile interface is difficult since the disturbed soil layer in these areas is very thin. In this study, the DIC technique is used to measure soil displacement on the soil-pile interface. Combined with model tests, a modified DIC technique can produce interfacial soil displacements being subjected to the influence of penetration rate and depth. Analyses on the test results show that development of interfacial soil displacements from the start of pile penetration can be classified into two stages—initial stage and stabilization stage. In the initial stage, interfacial displacements sharply increases until 0.2 mm due to pile penetration followed by a quick decrease, while interfacial displacements tended to vary around 0 mm in the stabilization stage. At the same penetration depth, interfacial soil displacements increase with the pile penetration rate. Meanwhile, with the increase of pile penetration depth, the accumulated interfacial displacements increase, and soil rebound in the stabilization stage decrease. The findings in this study can shed some light into the study on the mechanisms of soil-pile interface behaviors.

Key words: modified digital image correlation(DIC), mesoscopic measurement, soil vertical displacement, soil-pile interface