The vacuum consolidated drain method is a consolidation improvement method in which drains fitted with caps with drainage hoses are installed at a specific depth in a clay layer, using the clay layer above as a negative pressure seal layer, making use of the negative pressure in the soft ground. Unlike conventional vacuum consolidated methods, sealed sheets are not needed, and so it can be used in circumstances where conventional methods have been difficult to apply, as follows:
- Improvement where there is a sand layer on the surface
- Improvement beneath water surface
- Improvement where an intermediate sand layer interposes
