Liquefaction Mitigation of a Submerged Silty Sand Site in Seismic Zone IV of India by Dynamic Compaction and Soil Replacement

Soil Liquefaction has been a major cause of damage to many Civil Engineering Structures like multi-storey buildings, storage tanks, bridges, etc. in seismically active areas during many past earthquakes. Therefore, it is essentially required to do Liquefaction Potential Analysis based on a detailed Geotechnical Investigation of a Site located in a seismically active zone and further suggest viable Liquefaction Mitigation Techniques for the Project concerned which may be a combination of more than one method using geotechnical fundamentals to produce an adequate solution for the concerned Site. A case study is being discussed and presented here wherein a combination of two most economical and easy to implement liquefaction mitigation techniques were recommended to be adopted at the proposed Seismic Zone IV site of India with a view that we could save our valuable available natural Mother Earth resources for our future generations with environmental sustainability as the prime focus. A combination of Dynamic Compaction and Soil Replacement at the top resulted in improved densification as well as converting a few liquefiable soil layers present to non-liquefiable ones, still leaving a few un-improved liquefiable layers at little shallow depths just below the ground level which made us to decide for geotechnical recommendations for the proposed Structure in favour of conventional footings with a rider to structurally stiffen the Structure to accommodate post-earthquake settlements, thus, avoiding deep pile foundation which would not have been cost-effective and could have used many available natural resources in the form of different Building Materials.