A new 150,000 square meter multiple use terminal (MUT) was planned for Manzanillo port to handle 2.5 million tons of general purpose cargo and bulk minerals per year. The contractor was to complete 5 platforms of 10,000 sq m each within a year with environmental friendly operating equipment and infrastructure. The terminal had to be constructed according to the highest international standards and the goal was to provide handling capacity above expectations.
The only problem was the extreme site conditions for the terminal platform – the soil CBR was <2%. Bulk handling of lead and zinc minerals, piled into mountains of ore on the dock, could reach loads of 35 ton/m2. The terminal foundation was constructed on vertical columns; therefore the reinforcement solution had to function as a load transfer platform.
Due to the extreme site conditions and project requirements, Innovator and Ancora Engineering turned to PRS to work together and develop a reliable design for a geosynthetically reinforced load transfer platform (LTP) utilizing geocells.
CONVENTIONAL SOLUTION
Load transfer platforms of concrete, hydraulic-bonded or composite geosynthetic (geogrid) layers were considered but too expensive or insufficient. The thickness of each layer of an unreinforced solution would have been much thicker.
PRS-NEOLOY SOLUTION
Neoloy Geocells were chosen for their excellent load distribution mechanism. Neoloy reinforcement acts as a stiff mattress, distributing vertical loads widely and reducing settlements. This serves as an effective load transfer platform to transfer applied loads directly to vertical columns. The pavement structure sits on a working platform of 5 cm lightweight concrete to create a stable working foundation.
Two layers of Neoloy Geocells 330-120 (120 mm height)with 12 cm of 1” gravel fill were installed directly over the working platform and compacted with an extra 3 cm overfill over each layer. On top of this a layer of 115/130 cm controlled subgrade undercut was placed with quality controlled compaction every 15 cm; this layer had a high elastic modulus (178 MPa) due to the Neoloy reinforcement underneath it.
Then another layer of Neoloy Geocells 330-120 was installed and filled with base layer aggregate (+3 cm overfill). The 20 cm granular base layer laid on top of that had a very high modulus, due to the Neoloy reinforcement. The platform surface layer was 25 cm Portland Concrete Cement slab.
BENEFITS
Unique geocell reinforced load transfer platform – excellent load distribution
Fast, simple installation – several weeks to install 10,000 sq m of pavement
Cost savings– reduced subgrade extraction, subbase and concrete layers
Modulus Improvement Factor –by 2-3x; enabled use of subgrade material
Subgrade improvement – 3D“mattress” stabilized extreme subgrade conditions
Confined drainage system – mission critical considering site conditions