Feasibility study of using acoustic emission signals for investigation of pile spacing effect on group pile behavior

Understanding the subsoil behavior subjected to group pile loading is of foundation important to clarify the group pile behavior. The acoustic emission (AE) signals produced by the stressed subsoil subjected to group pile loading are expected to contain useful information about the behavior of group pile. In this study, measurements of AE signals generated during group pile loading were performed. To evaluate the effect of pile spacing, group pile loading tests were performed with two different pile spacing to represent strong and weak group effects. Results showed that the group pile in case of narrow spacing might significantly reduce the apparent stiffness of the ground, which was evidenced by lower values of ground secant modulus and the released AE energy. In addition, center pile carried more load and emitted higher level of AE compared with other pile positions when the pile spacing was narrow. However, it is observed that such group pile effect was affected by the loading history as well. Considering the high consistency between the results of conventional load-settlement measurement and the AE monitoring, it is therefore suggested that the AE monitoring can be potentially used as an alternative method for evaluation of the group pile behavior.