Reinforced granular column for deep soil stabilization: A review

The engineering structures constructed on thick deposits of soft soil strata have problems of low bearing capacity, excessive total and differential settlement, lateral spreading etc. To mitigate such problems, different ground improvement techniques are available namely; vertical drains, lime/cement column, stone (granular) column etc. in view of their proven performance, short time schedule, durability, constructability and low costs. Stone column technique seems to be very suitable and favourable ground improvement technique for deep soft soil improvement. Further to prevent excessive bulging, squeezing of stone into soft soil, stone column can be encased with suitable geosynthetic. Another advantage of encasement is having high load carrying capacity and lesser settlement of composite foundation. This paper presents the current state of the geosynthetic encased stone column as a ground improvement technique. A review is provided aiming to: (a) identify key considerations for the general use of encased stone columns, (b) provide insights for design and construction, (c) compile the latest research developments. Case histories of field applications and observed field performance are cited to portray different stone column applications and observed effectiveness. The paper identifies areas where more research is needed and includes recommendations for future research and development.