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Soil Densification Using Dynamic Compaction Operation

IP.com Disclosure Number: IPCOM000219888D
Publication Date: 2012-Jul-17

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The IP.com Prior Art Database

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SOIL DENSIFICATION USING DYNAMIC COMPACTION OPERATION

Vinod Duggal, Sr. Geotechnical Engineer, The M. W. Kellogg Co.


C. Patrick Chu, Manager, Civil Engineering Division, The M. W. Kellogg Co.

ABSTRACT

On an LNG (Liquified Natural Gas) project in the Far-East, dynamic compaction technique was successfully used to densify granular sub-soils in 1980. The procedure was developed and the system monitored completely by the authors of this paper. Moderate to substantial increase in the relative density, hence the shear strength of subsoils was achieved immediately after dynamic compaction operation.

BRIEF PROJECT DESCRIPTION

The LNG facility is spread on the site which is approximately I km. by I km. in plan dimension and has a slightly hilly to very hilly topography. The facility consists of four major units: I) a main plant site called inside-plot; 2) a tank area containing 4 LNG tanks; 3) a cooling water intake structure and debris line and 4) a pipe track connecting the cooling water intake structure and the LNG tank area to the inside plot.

GEOTECHNICAL INVESTIGATION

Preliminary Geotechnical Investigations were conducted at the job site in 1974 and in 1978. Final Geotechnical Investigation was conducted in the last quarter of 1979. A total of 44 borings and 17 dutch cone penetration tests (DCPT,s) were conducted across the site during the final Geotechnical Investigation Program in 1979. In 1980, over 300 DCPT, s were conducted in the inside-plot to identify areas requiring sub-soil densification and to
check the improvement after the sub-soil densification program. Details of these DCPT's are given below under Soll Improvement Within Inside Plot Area.

SITE GEOLOGY

The site[lies within a region that is part of northwest borneo geosyncline, which is believed to have developed towards the end of the cretaceous age. The axes of later Pliocene folding are generally in the east-northeast and west- southwest directions. Major faults are almost parallel to the fold axis.

Subsidence and sediment deposition are understood to have commenced in oligocene times and continued into the miocene. The deposits in the region are of the nyalau formation of miocene age. Most of miocene sediments are considered to have been derived from previously compacted, folded, and uplifted rocks lying to the south and east of geosynclinal trough. The thickness of nyalau formation is in excess of 3000 m.


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During late pleistocene times, the sea level was gradually lowered relative to the land; thus, old beach deposits are not found up to about 15 m above present sea level. Large areas of white quartz sand, which is suitable for use in the glass-making industry, are found in the region.

The site area itself is underlain by sandstones, siltstones and mud~tones of the nyalau formation. The sandstones and mudstones are found in beds ranging from a few centimeters to several meters in thickeness. The sandstone is generally brown to gray and fine...