Our Ravin Nag will be presenting on March 12th at 11.30am
A marginal fill that contains high silt and/or clay content can generate excess pore water pressure in a structure. Prior research and long-term project successes have proven that marginal soils can be effectively used in the construction of reinforced slopes when an adequate drainage system is incorporated within the structure. To hear more about cases in which these techniques have increase efficiencies while decreasing costs, make sure to watch our Business Unit Manager – Mining & Geosynthetics, Ravin Nag’s presentation at the 21st annual Tri-Party Transportation Conference and Trade Show.
Co-authored by Maulik Upadhyay and Jasmina Nikodinoska, the paper describes our ParaDrain® combined reinforcement and drainage geogrid. This draining geogrid is comprised of a network of longitudinal and lateral strips. A longitudinal strip consists of high-tenacity polyester yarns with polyethylene sheathing, and is profiled into a channel capped by a geotextile. This creates a drainage channel on the surface of each longitudinal strip of the geogrid, which facilitates the consolidation and dissipation of pore water pressure rapidly.
Four reinforced soil projects using marginal soils are presented in the paper:
- The first project is the construction of two large storm water detection ponds, 140 meters by 40 meters each. Due to the size of these ponds and excavation required, import of granular soils is very expensive. In addition, disposal of excavated clayey material from the pond would incur significantly higher costs. The option to design and construct 2:1 reinforced slopes using on-site excavated native soils and draining geogrids was selected and approved.
- The second project is the construction of 4.2m high, 104m long, 60-degree vegetated reinforced slopes. The original design was to deploy six layers of reinforcement geogrid at 4m length, and 0.7 meter spacing and use quality granular fills. However, no source of suitable granular soils is available on or near the site. A redesigned reinforced slope using on-site sandy silt soils that were being wasted from nearby sites and draining geogrid was proposed and approved.
- The third project is the construction of MSE berms in a landfill perimeter to increase the waste storage capacity. Clay backfill and draining geogrids were utilized to construct the MSE berm.
- The fourth project is in an infrastructural project that will expand a road through a wetland. The traditional method of soil removal and replacement with a crushed rock road-base was not permitted in this environmentally sensitive area. Instead the project could only proceed if the soil horizon would have minimal disturbance and the integrity of the wetland and aquifer would be kept in-tact. A basal reinforcement pad was created, and was pre-loaded using a surcharge from native material and draining geogrids. The choice of the draining geogrid permitted the use of onsite native soils to build the preload area. The use of the draining geogrid design saved an estimated $5 Million to the alternative traditional methods.
Ravin Nag’s presentation “Case Histories of Reinforced Slopes Using Marginal Fills and Draining Geogrids” will be held at the Sheraton Hotel Red Deer in the Workshop II, Savona Room, on March 12th from 11:30am to 12pm, as it can be viewed in the conference program.