Menard Vacuum consolidation has been invented
by Mr. Jena-Marie Cognon, co-foundator of Menard Soltraitement
in the late 80's.
It has been developed in order to get rid of the limitations
of the vertical drains + preloading method which can be time-consuming
and highly sensitive to circular failure problems. The Menard
Vacuum Method has been patented.
It utilizes the isotropic atmospheric pressure to consolidate
soft saturated clays or silts.
Although the principle
is similar to the Vertical drains + pre-loading method, the
preload is applied by the creation of Vacuum under a membrane
initially installed on the soft ground.
A complex network of horizontal and vertical Menard Cylindrical
drains connected to water and air pumps permits the removal
of the water and air from the compressible soil for a fast consolidation
process.
The depressure of -0.7 to -0.8 bars reached under the membrane
is equivalent to a preload of 4m of classical surcharge by fill
or sand.
As the vacuum pressure is isotropic, the deviatoric tensor
of stresses is not modified by the load.
Therefore. there is no risk of failure and the Menard Vacuum
Method allows a rapid construction of high embankments with
virtually no risk of circular failure, getting rid of the time-consumming
expensive use of counter-berms and step-by-step loading inherent
to the classical drain+surcharge method.
The field of application of the method ranges from
highway embankments, harbours to airport runways, sewage treatment
plants and industrial buildings.
A complex network of inter-connected Menard Vertical and Horizontal
cylindrical drains connected to air and water vacuum pumps is
initially installed.
The membrane is installed on the surface of the soil with
sealing trenches dug at the periphery of the area for an efficient
tightness control over the treatment area.
Menard know-how and a constant quality control program are absolutely
necessary to guarantee the success of the method
