Impact of Footing Shape on Dynamic Properties and Vibration Transmission Characteristics of Machine Foundations

Due to immense infrastructure development activities, a study on the vibration generated by heavy machinery, construction activities, highway and railway traffic movements has gained importance in recent years. The present study investigates the influence of shape on the system and vibration transmission characteristics of block machine foundations under dynamic loading. A series of block vibration tests were conducted on model foundations laid on the local soil available at IIT Kanpur, India, to evaluate the system characteristics of machine foundations. The vibration transmission characteristics of the foundations were investigated using a 3D finite element (FE) analysis. Three different shapes of foundation (circular, square, and rectangular) were considered for the intended purpose. The effect of the loading intensity on various parameters such as natural frequency, soil stiffness, and damping coefficient was investigated. In addition, the shape effect of foundations on the dynamic shear strain, shear modulus, and the elastic uniform compression coefficient was suitably assessed. The efficiency of a wave barrier in mitigating the machine-induced vibration was investigated. It can be observed that the shape of foundations significantly influences the system characteristics. The circular and square foundations perform better than the rectangular foundation at higher loads. In contrast, the vibration transmission characteristics of block foundations are unaffected by the shape of the foundations. The transmission ratio decreases with an increase in the frequency at the pick-up points located away from the vibration source. It can be noted that the absolute damping varies significantly in the presence of the wave barrier at higher frequencies.