This is the most reliable method of shoring an excavation/soil face and in some cases is the only acceptable type of shoring allowed. 

Caisson walls allow very little horizontal and vertical soil movement, ensuring that existing buildings next to an excavation are properly supported and are not damaged by construction activities. 


In downtown Toronto, caisson walls are almost exclusively the only method of shoring used.  Caisson walls are continuous concrete walls constructed of interlocking vertical concrete piles. 


They are relatively impermeable and minimize the flow of groundwater into a construction site.