<p><p><figure id='attachment_2624' style='max-width:572px' class='caption aligncenter'><img class="wp-image-2624 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Schematics of the construction sequence for Sand Compaction Piles." width="572" height="326" /><figcaption class='caption-text'> Construction Sequence for Sand Compaction Piles (Figure from Barksdale (1987), after Tanimoto (1973))</figcaption></figure><h2>Basic Function</h2>Sand compaction piles are used to increase bearing capacity, prevent stability failure, reduce settlement, accelerate consolidation, and increase liquefaction resistance.<br><h2>Advantages:</h2><ul> <li> Rapid construction, less risk of intrusion of soil into the pile (compared to stone columns),</li> <li>The hole is fully supported during construction preventing collapse</li> <li>Liquefaction prevention</li> <li>Settlement reduction.</li></ul><h2>General Description:</h2>Sand compaction piles (or columns) are constructed by inserting sand into the ground through a pipe and compacting the sand by vibration, dynamic impact or static excitation to construct a compacted sand pile in soft ground. The sand pile and the surrounding soils are densified by the construction process. The principal concept for application to sandy soils is to increase the soil density by insertion of additional granular material into the ground. The principal concept for application to clay soils is reinforcement of the clay soil and provision of a drainage pathway.<br><h2>Geologic Applicability:</h2><ul> <li>They can be installed in a wide range of soils, from soft clays to sandy soils.</li> <li>Have been installed up to 70 m deep and usually extend to a bearing stratum.</li></ul><h2>Construction Methods:</h2>Sand compaction piles are installed by driving a pipe through loose sand or soft clay using a vibratory or nonvibratory method to densify loose sand and displace soft clay. After reaching a desired depth, the pipe is backfilled with sand. The sand pile and the surrounding loose soil are then densified by repeated penetration and extraction processes from the depth to the ground surface. In addition to sand, other granular materials, such as stone, construction waste, slags, oyster shells, and granulated coal ashes, etc. have been used. Sand compaction piles generally have diameters varying from 60 to 80 cm and they can reach up to 70 m in depth. The angle of internal friction of sand compaction piles typically ranges from 30^oto 40^o depending on the construction procedure.<br><h2>Additional Information:</h2>This technology is common in Asia, especially in Japan, for improvement of reclaimed land and foundations of embankments, railroads, quay walls, piers, breakwaters, tanks, etc. Specialty contractors are also available in the United States for this technology; however, only a few projects have been completed, mostly in California. Among these projects, other granular materials instead of sand have been mostly used. The design principles of sand compaction piles in loose sand are the reduction of void ratio and the corresponding increase of SPT N-value. The design principle of sand compaction piles in soft clay is based on composite foundations, which have higher composite moduli and shear strength values. The typical quality assurance method is the SPT method.<br><h2>SHRP2 Applications:</h2><ul> <li>Embankment and roadway construction over unstable soils</li> <li>Roadway and embankment widening</li></ul><h2>Example Successful Applications:</h2><ul> <li>Kansai International Airport Island Seawall Construction, Osaka Bay, Japan</li> <li>Hokkaido Highway Construction Project, Hokkaido, Japan</li></ul><h2>Complementary Technologies:</h2>Sand compaction piles are generally a standalone technology. If there is a need for additional drainage, PVDs or other methods of drainage can be utilized.<br><h2>Alternate Technologies:</h2>Vibrocompaction, stone columns, aggregate piers, vibroconcrete Columns, deep dynamic compaction<br><h2>Potential Disadvantages:</h2><ul> <li>Not commonly used in the United States</li> <li>Smearing effects when constructed in clay</li> <li>Greater replacement ratios are necessary compared to other columns (lower stiffness than other columns)</li> <li>Recent trends indicate a need for substitute materials due to rising costs and diminished availability of sand.</li> <li>Vibration and noise during construction</li></ul><h2>Key References for this Fact Sheet:</h2>Aboshi, H., Mizuno, Y., and Kuwabara, M. (1991). “Present state of sand compaction pile in Japan.” Deep Foundation Improvements: Design, Construction, and Testing. ASTM STP 1089, ASTM International, West Conshohocken, PA.</p><p>Barksdale, R.D. (1987). State of the Art for Design and Construction of Sand Compaction Piles, Technical Report REMR-GR-4, US Army Corps of Engineers, 57p.</p><p>Kitazume, M. (2005). “The Sand Compaction Pile Method.” Port and Airport Research Institute, Yokosuka, Japan. Taylor &amp; Francis, 2005, 232p</p></p>