Performance of geotextile encapsulation on lime column stabilized Pontian marine clay
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Date
2015
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Publisher
Universiti Teknologi Malaysia
Abstract
Previous researches reported deep lime stabilization such as lime column, lime pile and deep soil mixing, effectively improved engineering characteristics of clay. However, crushing at column head and larger settlement for upper soil profile were often encountered due to insufficient confining pressure by surrounding soil. Lateral displacement which reduced column load capacity was observed especially on young column subjected to lateral loading. From previous researches, geosynthetic confinement successfully increased load carrying capacity and reduced settlement of granular column. Hence, geotextile encapsulated lime column (GELC) was proposed. Laboratory model tests on lime column and GELC stabilized Pontian marine clays were conducted to examine geotextile encapsulation effect on compression behaviour and horizontal shear resistance of lime column. Displacement, stress at various locations and column lateral bulging were observed. It was found that geotextile encapsulation slightly reduced settlement on lime column stabilized sample before column creep limit was exceeded but the geotextile effect reduced as compressive pressure increased. High compressive pressure and small area ratio caused settlement to be governed by surrounding soil properties. Confining pressure by surrounding soil had greater effect on settlement reduction, compared to confining pressure by geotextile encapsulation. However, geotextile encapsulation increased lime column strength by 70 percent at 8 percent strain and reduced bulging of lime column under compressive load. Geotextile encapsulation also increased horizontal shear resistance of young aged lime column, by 32 percent for samples aged 14 days. Failure mode observation showed that geotextile encapsulation protected lime column from defects such as cracks and lateral displacement under horizontal load, especially for lime columns at early age. In conclusion, geotextile encapsulation acted as a protection to lime column, especially for young aged column. A new correlation equation to estimate lateral force in GELC was derived based on laboratory test results, with modification on equation proposed by Kivelo and Broms
Description
Thesis (PhD. (Civil Engineering))
Keywords
Soil stabilization, Columns—Testing, Geosynthetic encased columns