• Journal of the Korean Geotechnical Society
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• v.25 no.9
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• pp.67-76
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• 2009

The problems of bearing capacity, settlement and shear deformation occur when constructing a structure such as harbor, airport and bridge on soft ground of marine clay, silty clay or sandy soil. Various ground improvement methods are applied to obtain preceding settlement of soft ground and strength increase. In this study, to analyze the applicability of PBD method in deep soft ground, the compound drainage capacity test was operated in comparison with SD. As a result of the test, a minimum drainage capacity of drain material was estimated to be more than $10\;cm^3/sec$ at a more than $400\;kN/m^2$ and less than $5\;cm^3/sec$ at a more than $500\;kN/m^2$ confining pressure in case of single core PBD. In case of double core PBD, it was estimated to be more than $10\;cm^3/sec$ at a more than $500\;kN/m^2$ confining pressure.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.29-41
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• 1999

This Paper applied a simple strength parameter averaging method to double layered systems consisting of the strong sand layer overlying the soft clay deposit. This study derived a formula which defines a critical depth as the strength parameters, and used the correction parameter, $\alpha$ to reduce an error of the strength parameter averaging method. The results of the method were presented in the form of dimensionless charts and were compared with the results of several solutions proposed by Satyanarayana & Grag, Sreenivasulu, and Meyerhof & Hanna. The results of the proposed method coincided with the method of Meyerhof & Hanna and the results obtained from FLAC. But the Satyanarayana & Grag method and the Sreenivasulu method overestimated the bearing capacity. Consequently, the bearing capacity of foundation on sand layer overlying soft clay layer can be approximately estimated by using the proposed dimensionless charts.