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http://dx.doi.org/10.7843/kgs.2009.25.8.33

Comparison on the Performance of Soil Improvement in Thick Soft Ground Using Single-Core and Double-Core PBD  

Yang, Jeong-Hun (Tunnel & Underground Facility Design, Sambo Engrg. Co., LTD.)
Hong, Sung-Jin (Dept. of Civil, Environmental and Architectural, Engrg., Korea Univ.)
Kim, Hyung-Sub (Busan New Port North Container Terminal Phase 2-1, Engrg. & Construction, Samsung)
Lee, Woo-Jin (Dept. of Civil, Environmental and Architectural, Engrg., Korea Univ.)
Choi, Hang-Seok (Dept. of Civil, Environmental and Architectural, Engrg., Korea Univ.)
Publication Information
Journal of the Korean Geotechnical Society / v.25, no.8, 2009 , pp. 33-45 More about this Journal
Abstract
The conventional single-core PBDs have been widely used in order to accelerate consolidation settlement of soft grounds. When using the single-core PBD in a thick clay deposit, a delay of consolidation may occur due to high confining pressure in the thick deposit and necking of drains. This study is to compare the performances of soil improvement by the single-core and double-core PBD installed at a site in Busan New Port which exhibits approximately a 40m-thick clay layer. An in-situ test program was performed at the test site where a set of the double-core PBDs and single-core PBDs were installed to compare the efficiency of each drain. In addition, the discharge capacity of each PBD has been measured using the modified Delft Test. A series of laboratory tests for estimating in-situ soil properties have also been performed in order to obtain input parameters for a numerical program ILLICON. The discharge capacity of the double-core PBD is higher than that of the single-core PBD in the modified Delft Test. However it is observed from the comparative in-situ test and numerical analysis that there is no difference in the performance of ground improvement between the two drain systems. This discrepancy comes from the fact that the amount of water released during consolidation in most common field conditions is much smaller than the capacity of even the single core PBD. And thus, considering actual field conditions, it can be concluded that the single-core PBD has enough discharge capacity even in the thick clay deposit such as this test site.
Keywords
Double-core PBD; ILLICON; Prefabricated board drain; Single-core PBD;
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