HomeVacuum Consolidation
Release time：Apr 28,2023
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VACUUM CONSOLIDATION OF SOIL FOR GROUND IMPROVEMENT
Vacuum Consolidation (or vacuum preloading) is a soft soil ground improvement method that is typically combined with Prefabricated Vertical Drains and Horizontal Drains (PVD+VCM) and basically is a solution to replace the use of a surcharge. Further to the installation of the PVD, it consists of the application of a suction force with vacuum to an isolated mass of soil in order to reduce the atmospheric pressure and excess water pore pressure present in the soil, resulting in a consolidation of the soil, an increase in the effective stresses without modifying the total state stresses.
The vacuum consolidation system consists of the installation of a drainage system (PVD) and Horizontal Drains, an isolation system and vacuum pumps. Once initialized, the vacuum is quickly distributed in the soil through the drainage system, reducing atmospheric pressure and excess pore pressure, creating a pressure differential between the prefabricated vertical drains (PVD) and the pore pressure present in the soils. This difference in pressures causes the water to flow vertically through the drain, causing a consolidation effect.
Vacuum consolidation method using cap-attached prefabricated vertical drains This is a soft ground improvement method using a piece of prefabricated vertical drain (PVD), Using this method, a PVD is capped at the top and inserted into the soft seabed clay and vacuum suction is applied to reduce the atmospheric pressure so that the pore water pressure is reduced and the effective stress is increased accordingly. Since the placement of airtight sheeting on the surface to maintain air-tightness is not required, this method is far superior to conventional methods in terms of cost effectiveness and labor saving.
Because the force used is a result from the vacuum effect of the atmospheric pressure, VCM eliminates the need of the surcharge after installation of the PVD´s and thus, it eliminates the associated costs of the surcharging process.
APPLICABLE SOILS & DEPTH OF IMPROVEMENT
The Vacuum Consolidation Method (VCM) is applicable for very soft to soft clays or silty clays with water and plasticity content. These types of soils are typically deemed unsuitable for any engineering use and on many occasions are recommended to be removed from site and to be replaced with expensive granular soils. With VCM, the “bad soil” becomes treatable and consequently useful for engineering purposes. The depth is limited by the thickness of the soft deposit and the capacity of the PVD installing machine. VCM projects can have depths of treatment in the range of 10, 15, 20, or 35m and even up to 45m.
SUNZO has a long track record in the field of vacuum consolidation. We have multiple vacuum consolidation systems within our range of techniques, amongst which No sand cushion vacuum consolidation , Vacuum consolidation for water and gas separation and the traditional vacuum consolidation method using a synthetic liner.
are installed by using our own PVD rigs. Every system has its own solution to overcome loss of vacuum in sand layers. Ask us about the possibilities
Application areas
Vacuum consolidation is used in the following markets:
Infrastructure：Vacuum consolidation is for example used for the construction of embankments for roads, railways, the preloading of runways and aprons for airports and infilling of port areas on soft deposits where stability is a major issue of surcharge is scarce.
Dredging and land reclamation： Vacuum consolidation can be used when reclamations are constructed on soft deposits and horizontal deformations need to be reduced.
Dredging and land reclamation： Vacuum consolidation can be used when reclamations are constructed on soft deposits and horizontal deformations need to be reduced.
Mining：vacuum consolidation is highly suitable for the used in Tailing ponds to create strength without the application of surcharge. The vacuum system can be installed from a barge or specialized custom made tools.
Construction：Vacuum consolidation is used to make green and brownfield areas suitable for construction of for example houses, warehouses and tank farms by reducing the residual settlement of the terrain.
Flood protection：vacuum consolidation is in the flood protection market to increase the stability of dikes and embankments during widening projects.
Advantages
Relatively fast, relatively inexpensive compared to surcharging.
The loading process commences immediately after completion of installation of the pumps and sealing (compared to weeks of waiting with surcharging).
The performance can be monitored in real time.
Disadvantages
This method is not so effective if there are sand layers present deep into the soft deposit.
Shallow sand or permeable layers can be overcome with a slurry wall isolation system.
This method requires careful monitoring during the installation of the membrane to prevent vacuum leakage.
Any commercial or operational questions? Any technical questions? Please contact
E-mail : sunzo-market1@shengzhounet.com
Tel : +86 136-0005-0009
