The soil is transformed from a solid to liquefied state due to reduced effective stress and increased pore pressure (Boulanger and Idriss, 1416). This paper will shed light on the analysis of the soil liquefaction phenomenon, the examination of the different methods for its prevention, and the techniques of the proper implementation of the preventions. The prevention methods are classified either as soil compaction techniques such as vibro compaction or as foundation techniques such as deep piles. A case study on a highly seismic region Calcutta, India which witnesses soil liquefaction will be presented.
Ground improvement techniques have been adopted in Asia, Europe and USA in variety of projects and particularly on ports and harbors as it works with the existing ground and can be tailored to meet settlement requirements and specific bearing capacity (Rodríguez, 58). Earthquake engineers have devised different methods to prevent soil liquefaction and mitigate its effects. Among the most common methods includes the vibro compaction. where soil is compacted by depth vibrators, vibro stone columns and dynamic compaction. All this methods enhance the densification of soil which in turn enables structures to withstand during soil liquefaction. Generally, these methods are more cost-effective compared with other traditional methods like piling or the use of seismic foundations (Boulanger and Idriss, 1413). These ground improvement methods are effective in mitigating liquefaction potential, reduce foundation settlement, increase bearing capacity, and provide slope stabilization as well as earthquake-induced lateral spreading (Rodríguez, 58).
Vibro techniques use large depth vibrators that are about 300- 500 mm in diameters that penetrate in the ground to a suitable depth. Continuous columns are then constructed up to the ground surface. There are four basic systems under vibro techniques that are used depending on