BSP Compactors consolidate ground for Iranian refinery project
Construction of the world’s largest petro-chemical refinery at the southern port of Assalouyeh on Iran’s Gulf Coast is the latest project to benefit from the use of the new generation of Rapid Impact Compactors (RICs) designed and manufactured by BSP International Foundations.
Two of the Ipswich-based company’s RIC9000 units, mounted to Kobelco SK480 hydraulic excavators, were shipped to Assalouyeh to carry out ground consolidation trials on the refinery site. The 20-kilometer long refinery being built by an international consortium and costing US$1.2 billion will process gas and oil extracted from the South Pars gas field. The refinery is being constructed on reclaimed land, protected by a boulder defence wall and extends the coastal plain by half a mile to the sea. The fill material comprises mainly rock mined from nearby coastal mountains and ranges in depth from three meters to 14 meters in depth at the seaward end.
The RIC9000 units commenced work on the Water Treatment area where they again proved their performance capabilities by compacting the fill material up to six meters deep. For the deeper infill areas up to the 14 meter depth, ‘free-fall’ dynamic compaction was used involving rigs dropping weights spanning 10 tonnes to 30 tonnes from heights up to 25 meters.
Following the trials, Soil Penetration Tests (SPT) were carried out to confirm the overall effectiveness of the RICs. Two compaction patterns were employed, the first being a ‘sweep-and-track’, a compaction method designed to cover a given area in the shortest time. The second, a ‘staggered’ pattern, was used whereby the corners of a rectangular area are initially compacted followed by intermediate positions. The second method is designed to mazimise the depth of compaction.
Straddling the Iranian and Qatari sectors of the Persian Gulf, the South Pars gas field is the largest in the world and belongs to both Iran and Qatar. Once all 12 development phases are complete in 2006, daily production is expected to be 300 million cubic meters and will drive up annual revenues from the field to around $2.8 billion.
BSP’s RIC compactors are available in five, seven and nine tonne modes and have been designed around a modified version of the company’s popular BSAP 357 hydraulic piling hammer. Mounted onto a suitably sized hydraulic excavator, the compactor is a major breakthrough in ground consolidation engineering. Compared to traditional drop-weight methods, the BSP units are fast, extremely versatile, manoeuvrable and are readily transportable.
In operation, the RIC’s 1.5 meter diameter foot stays in contact with the ground, ensuring efficient transfer of energy to the ground at all times. Energy is imparted by dropping the weight through a relatively low height of up to 1.2 meters at a rate of between 40 to 60 blows per minute. Although the energy per blow is small by comparison to conventional dynamic compaction, the rapid blow frequency amply compensates and can result in much greater total energy input per unit on site.
Because the foot is in constant contact with the ground, there are no flying debris and no danger from a large falling weight. These safety advantages over conventional dynamic compaction means that other activities can be performed in the immediate vicinity can proceed during the compaction process.
The energy, blow count and penetration are controlled by a data acquisition system providing detailed records of the work done and performance achieved which enables the contractor to confirm progress to clients and consultants.
Potential applications for the RIC include compaction of loose soils to improve bearing capacity and mitigate possible liquefaction, compaction of environmental remedial site backfills or use in tandem with other ground improvement techniques to reduce the need for confirming fills or excessive stone in the upper layers.
Use of BSP’s Rapid Impact Compactors have become the standard method for ground consolidation by increasing number of civil engineering contractors around the world. Already the RIC has established an impressive compaction record on remedial projects in a wide variety of ground conditions in the UK and other countries including Canada, China, West Kazakhstan, the USA and now Iran.