References
General Lázaro Cárdenas Refinery - Minatitlan
MEXICO, 2005-2007
Soil improvement and deep foundations works for the construction of an oil refinery.
In 2003, the national oil company of Mexico PEMEX started a new refinery project at Minatitlan in Veracruz state. CIMESA, the Mexican subsidiary of Solétanche Bachy, was awarded the contract for soil improvement works and deep foundation works.
Geotechnical conditions
This part of the Gulf of Mexico is a very marshy coastal plain underlain by very thick strata of compressible soils. The land on which the refinery was constructed consisted of alternating strata of soft to very soft clay and loose to fairly loose sand of varying fineness. In particular, at depths of between 0 and 20m, there are two layers of liquefiable sand that required major soil improvement works. The strata with adequate bearing capacity to take the foundation loads were found at depths of between 25m and 45m.
Techniques
A trial site was used to validate the technical proposals, i.e. dynamic compaction to improve the surface soil stratum and compaction grouting to improve the deeper levels, together with Starsol piling (drilling the soil using a hollow auger and then injecting concrete as the auger is withdrawn) for the foundations.
Site
The first stage in the works consisted of surface soil improvement. This was then followed by deep soil treatment and, finally, the construction of the foundations. The immense size of the site required major mobilization of resources:
- dynamic compaction: up to 5 cranes,
- starsol piling: 2 x 12,000 Starsol,
- piles drilled under drilling fluid: 9 rig,
- barrettes: 1 rig to construct the 76 barrettes measuring 2.70 x 0.80m and a depth ranging from 35 to 45m,
- compaction grouting: 4 high-depth rigs.
More than 500 people were employed for the successful completion of the project.
Techniques
Compaction grouting is a process used for improving the engineering characteristics of a soil, through the high-pressure injection of stiff mortar through cased boreholes.
A pile is a structural element driven into the soil for transferring loads and prevent deformation. Its slenderness ratio is not limited.
Pile shafts can be uniform and rectilinear, telescopic and belled out.
Piles can be installed either separately or in groups. They can also form a retaining wall, a mixed curtain wall, contiguous piles, secant piles and composite curtain walls, such as Berlin walls and similar. Piles are also used as precast beams to be placed in the structure of the building they support.
Soil-improvement techniques involve changing soil characteristics by a physical action, such as vibration, or by the inclusion or mixing in the soil of a stronger material. The aim of this process is as follows:
- increase the load-bearing capacity and/or the shear strength,
- reduce both absolute and differential settlements or in certain cases, accelerate them,
- to mitigate or remove the risk of liquefaction in the event of an earthquake or major vibrations.
Ouvrages
Soletanche Bachy can deliver a building platform ready for construction
Voyage au coeur de l'ingénierie de pointe
Find out more about our expertise by:
