Menard Vacuum™ Consolidation
The Menard Vacuum™ Consolidation method is a proprietary system used for preloading and consolidating soft and very soft saturated impervious soils. The procedure consists of installing vertical and horizontal vacuum transmission pipes under an airtight impervious membrane and evacuating the air below the membrane thus imposing an atmospheric pressure on the soil.
Vacuum Consolidation can be undertaken in isolation or in conjunction with surcharging, the latter, typically for embankment construction. The imposition of the isotropic pressure, which is imposed throughout the soil mass, provides a significantly more efficient loading system than normal surcharging. This remains the case, when vertical drains are used in conjunction with surcharging. Vacuum Consolidation generates rapid consolidation as well as increased stability, when concurrent with surcharging and significantly reduces the period required for the consolidation
Advantages:- Significant time savings over other consolidation methods
- Loading and construction can proceed as early as two weeks after process has started
- Isotropic consolidation eliminates the risk of failure under additional loading of the permanent construction
- No risk of slope instability beyond boundaries
- Controlled rate and magnitude of loading and settlement
Whilst many projects have been completed overseas, significant amongst which are the jobs in Korea described below, two major projects have been undertaken in Australia. The Emigrant Creek bridge abutment approach embankment on the Ballina By-pass section of the upgraded Pacific Highway and two sites on Fisherman’s Island, for the Port of Brisbane Authority, in areas of reclamation.
The Emigrant Creek project involved the treatment of a depth, 25 metres, of particularly complex soft, homogeneous clays. The vacuum pressure was applied in conjunction with surcharge to a maximum of fourteen metres. Six metres of settlement induced by this load combination was recorded before the vacuum application was terminated.
The projects at the Port of Brisbane were also successful in accelerating the consolidation of the reclaimed soils, however, the jobs differed, in that, at the Port of Brisbane there was no surcharge, only vacuum pressure was applied also a cut-off barrier was required surrounding the soil blocks to address the permeable layers in the reclaimed material
Kimhae and Yangyoo sewerage treatment plants
In South Korea, Menard Vacuum combined with surcharge and Dynamic Compaction of the material placed over the settled surface has been successfully used to allow the construction of the Kimhae Sewage Treatment plant on 25 to 43 m of highly compressible clay.
The Sewage Treatment Plant of Kimhae is now in full operation and no residual settlement has been recorded to-date which attests to the efficiency of the method.
Further to the success of the construction of this plant, the city of Kimhae has awarded to Menard the soil improvement of the sewage treatment plant of Jangyoo, located next to the previous treatment plant. Soil improvement works are now in progress, with 60,000 m2 of compressible clay up to 40 m deep subject to vacuum consolidation. Settlements so far range between 3 to more than 6 m.
