ANALYSIS OF MACHINE FOUNDATIONS UNDER BLAST LOADING

Abstract

Machine foundations provide an effective working platform for machines to operate in a stable, efficient and safe manner. Analysis and design of these foundations are relatively complex because they are subjected to static loads from the weight of the machine and the foundation block, and dynamic loads caused by machine induced vibration during its operation. Additionally, these types of foundations may be subjected to a variety of disturbances as a result of natural occurrences or other circumstances such as, seismic events, wind, blast, or multiple closely spaced machine foundations in the vicinity of the foundation, which further complicates its design and analysis. In recent years, blast loads resulting from terrorist attacks, explosion in adjacent power plants, mining activities, or military explosions, pose a huge threat to the structural integrity of foundation systems. These blast loads are likely to cause substantial displacements that exceed the allowable limits for which the foundations are designed during normal operation, potentially leading to excessive settlements and even structural collapse. Therefore, the combination of machine induced dynamic loads and blast-induced vibrations results in highly non-linear behaviour of the soil-foundation system, and the mechanical response of soil also changes. Hence, an increased understanding to protect the foundation system against blast loads becomes crucial. A comprehensive review of the research conducted on the behaviour of machine foundations subjected to different dynamic loadings are discussed in the present study. The historical evolution in the analysis of machine foundations is explored and a wide range of analytical, numerical, and experimental research carried out in this field are examined. Studies dealing with blast loading and the behaviour of structures and substructures when subjected to such loading conditions are also reviewed, with particular emphasis accorded to the method of modelling the blast load. The critical review of literature revealed research gaps such as, lack of studies in the context of machine foundations considering the interaction of harmonic and pulse loads, elastic to elastic-plastic transition of the mechanical response, consideration of negative phase of blast on analysis of foundations, emergency shutdown event of machine, which could be addressed through the problems undertaken in the present study. In view of this, the current work takes a step forward towards analysing machine foundations under harmonic and blast loading by means of theoretical formulations and numerical computations.