Numerical Modeling And Analysis Of Pile Supported Embankments
Rao, Krishna Nag
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Very soft clays are often avoided in construction due to their low shear strength and high compressibility. Special construction methods are adopted when embankments are constructed on very soft clay or peat. Design of structures on soft ground, where the structure impose large loads onto the ground raises several concerns on factors like bearing capacity failure, differential settlements, lateral pressures and structural instability. Shallow and deep stabilization of soft ground are most frequently used special construction techniques adopted in geotechnical engineering. Chemical (lime and cement) stabilization has been extensively used in both shallow and deep stabilization in order to improve inherent properties of soil such as strength and deformation. The shallow stabilization involves mixing surface soil with stabilizers like lime. The other technique involves forming columns of chemically treated lime in the soft soil. The lime column (chemico-pile) soil improvement method has been used in a full-scale test embankment project located at Nong Ngo Hao site near Bangkok, Thailand. A numerical solution was provided in order to evaluate the behavior of the embankment using Finite Element (FE) program PLAXIS. The predicted embankment behavior using PLAXIS has been compared with actual field data in terms of excess pore pressure, settlements, and lateral displacement. The predicated results were in good match with the actual field results. In addition, parametric studies were performed in order to understand the embankment behavior when reinforced with geosynthetics. Also, change in geosynthetic stiffness, pile stiffness, foundation soil modulus and embankment property were modeled. Results indicated that geosynthetics included in the embankment fill produced considerable increase in load transfer when placed at 100mm above ground surface.