Typical cross section through basal reinforced expressway embankments
Typical foundation undrained shear strength profile along CLLEX
Installation of Alidrain PVDs
Installing MIRAFI PET600 basal geotextile reinforcement above sand blanket layer
Placement and compaction of embankment fill
Expressway section almost complete
Omega Mine extends AMD treatment capacity with dewatering
At Omega Mine in West Virginia, GEOTUBE® GT500 units help the West Virginia Department of Environmental Protection treat and dewater acid mine drainage from abandoned mines while supporting long-term capacity and compliance.
Dredging and reuse of contaminated sediments
Embraport used dewatered contaminated sediments as structural fill within its terminal platform, saving 400,000 m3 of imported material and reducing earthfill platform costs by 20% to 30%.
MSW incineration and power plant platform, Yuxi City, Yunnan Province, China
A USD 50 million MSW incineration plant in Yuxi City uses reinforced segmental block retaining walls to form platforms in rugged terrain and process up to 1,000 tonnes of waste per day while generating electricity.
The Central Luzon Link Expressway (CLLEX) is a 30 km long, four-lane expressway linking several existing expressways in the Central Luzon region of the Philippines. The project aims to shorten the travel time from Metro Manila to Cabanatuan City, which serves as the hub city for the Pacific Ocean Coastal Area Development. Once operational, the travel time from Tarlac City to Cabanatuan City is expected to be shortened from 70 minutes to 20 minutes. The CLLEX traverses rural areas covered with agricultural farms where local rivers and farm roads intersect the CLLEX alignment. In these locations, abutment embankments are constructed for overpass bridge structures to minimize interruptions to the local communities.
The foundation soil profile along the length of the CLLEX mainly consists of a soft clay surface layer varying in depth from 2 m to 8 m. In many locations, the groundwater level (GWL) is near to the ground surface. The soft clay has an overconsolidated surface crust in the region above GWL. Below this upper soft clay layer is a medium stiff silty clay stratum. Embankment instability and excessive post-construction settlements over these soft foundation soils were a major concern for the project.
Consequently, a combination of basal geosynthetic reinforcement and prefabricated vertical drains (PVDs) were used to improve initial embankment stability and accelerate consolidation of the soft foundation layer. To provide the required embankment stability, MIRAFI® PET600 geotextile reinforcement was chosen as the basal reinforcement, while Alidrain® PVDs installed at 1 m spacings were chosen to accelerate the consolidation of the soft foundation. It was estimated that settlements of up to 1 m could be expected over a 5-month period with this PVD layout with a 2 m surcharge.
In constructing the embankments, the surface vegetation layer was first removed and then a layer of MIRAFI Polyfelt TS40 nonwoven geotextile separator installed. On top of this, a sand blanket layer was constructed to remove the excess pore water from the base of the embankment and to provide a stable working platform for the PVD installation machines. After the PVDs had been installed, the MIRAFI PET600 geotextile reinforcement was laid in a continuous length across the width of the embankment. The geotextile reinforcement was sewn together onsite to provide a continuous coverage at the base of the embankments.
Next, a 1 m thick gravel layer was placed over the MIRAFI PET600 geotextile reinforcement and compacted. The embankment fill was placed in lifts and compacted to 95% Standard Proctor compaction. The expressway pavements were then constructed on top of the completed embankments. Finally, the side slopes of the embankments were hydroseeded to provide vegetation growth.