Milan-venice railroad reinforced soil slope

Italy, Lonigo-Montebello (VI) 
PET woven geogrids with PVC coating as a structural element for reinforced soil slope construction

Problem:
the section of the Milan-Venice railroad between the Lonigo and Montebello stations is running on embankment with average height of 6 to 7 m with slopes that range from 26° to 35°. Already in 1985-1986 the presence of cracks on the embankment edges was noted.
This phenomenon promoted an in-depth geotechnical investigation aimed at determining the geomechanical characteristics of the embankment and establishing the documental basis required to determine and plan further stability works.
The circumstances leading to the formation of the cracks can be traced to:

•  construction of the embankment using clay or clayey silt;
• the seepage of rainfalls into the embankment, in particular in the sections where previous stabilization works (jet-grouting) occured;
• possible erosion and seepage effects at the foot of the embankment caused by the presence of streaming water with considerable flow rates and significant outflow speed.

Solution:
the stabilization works involved the collection of the platform run-off water, erosion control on the upper embankment with a 34° slope, construction of reinforced soil at the base of the embankment to contain its movement.
Erosion control was performed using SintexMat®, a three-dimensional geomat able to hold the topsoil and at the same time to guarantee the complete revegetation of the embankment.
The reinforced soil at the base of the embankment was executed with a face slope of 65° from the plane using as reinforcement, Edilgrid geogrids placedat layers of 65 cm thickness with tensile strength that varies from 55 kN/m to 110 kN/m.
At its base a 50 cm deep amelioration was performed, separating the on-site soil from the dry soil using Geodren® PPST 300, polypropylene nonwoven geotextile. Following the stabilization works, no new deformation phenomena were seen, nor was there an increase in the existing ones, confirming the validity of the technology used (reinforced soil and control of surface erosion).