Train I - Inside Battery Limits (ISBL) Project for LNG Plant in Africa
Train 1 - referred to as ISBL (inside battery limits) for the LNG plant in West Africa was designed to support all the static, dynamic and live loads produced from the structures, plan and equipment used during the gas purification and distillation processes.
Prior to main production an extensive test section was performed to verify the DSM equipment, installation procedures and the final mix design would produce a soil cement mix with sufficient strength and uniformity to fulfill the design criteria and to reach the desired installation depth.
Part of the test section was to conduct a load test on a section of elements installed after 90+ days. These elements tested to more than twice the design load with no significant movement recorded.
More than 462,000 cubic meters of DSM soil-cement was installed in a closed grid formation. This grid comprised of more than 6,200 elements of DSM; installed in seven months (October 2008 to May 2009)
DSM rigs equipped with double axles were used to stabilize the soil, installing each element to the design depth of 23.7 meters. The penetration depth, penetration/withdrawal speed, rotation and injection volume of the mix were monitored in real-time using a bespoke QA/QC electronic monitoring system.
Final quality control of the product was carried out by cores of soil cement being extracted from DSM columns 28 days after installation and samples from these cores were tested for their unconfined compressive strength. Inspections of the cores were also conducted to check the uniformity of the mixed soil-cement. The required strength was 120 psi at 90 days of which the majority of samples tested exceeded at 28+ days.
Project Highlights
- Installed over 6,200 DSM elements creating a foundation grid work of stabilized soil enabling the construction of the processing facility.
- Over 462,000 cubic meters of loose sandy fill was improved with DSM.
- DSM rigs equipped with two axles were used to improve the soil to a depth of 23.7 meters, terminating in the medium dense sand strata.
- The construction with DSM favored the overall schedule of the Project by moving ahead by six months the completion of the concrete works.
