Dynamic Response of a Machine Foundation Using Different Soil Constitutive Models

Machine foundations are subjected to repeated abnormal and complex loads due to machine vibrations. The response of such foundations should be examined by considering the effects of small strain stiffness, stiffness degradation, and repeated loads. However, no concerns are given in the literature to investigate the response of machine foundations using different soil constitutive models. This study investigates the influence of using simple and advanced soil constitutive models on the behavior of a machine foundation resting on a sandy soil. Linear elastic (LE), elastic perfectly plastic (MC), and hardening small strain stiffness (HS small) models have been utilized to address the aim of the study. The maximum amplitude of vibration has been taken as a percentage of the allowable bearing capacity of the soil (Qa) to investigate the implicit influence of the stress level of vibration. The results showed that the LE and MC models underestimate the settlement of the machine foundation, even for very low stress level of vibration. It was also noticed that the MC model produces results very close to the LE model for a vibration amplitude equal to or less than 25% of Qa. Moreover, it has been noticed that the effect of the soil model on the produced results rises as the vibration frequency or the stress level of vibration increases. Finally, a limit for the vibration stress level with no accumulation of settlement has been set based on the findings of this study. This study provides an in-depth analysis of the response of the machine foundation and how this response is influenced by the soil model. Thus, it helps to achieve better design and more robust research in the future.