Investigation of Creep Properties of Soft soil Mixed Nano-Silica

Nuri Kordgeshlagi, Arezoo and Negahdar, Alireza and Houshmandi, Siab (2015) Investigation of Creep Properties of Soft soil Mixed Nano-Silica. Masters thesis, University of Mohaghegh Ardabili.

Text (بررسی رفتار خزشی خاک های مخلوط شده با نانوسيليس درشرایط آزمایشگاهی) Arezoo Nuri Kordgeshlagi.pdf Download (402kB)

Abstract

The compressibility behavior of clay soil has been a major concern in geotechnical engineering. When buildings, embankments and other structures are built on clay soils, large settlements can often be found. Especially, time dependent deformation in structures built on soft soil may cause a damage. Therefore the study of of creep behavior of clay soil for geotechnical application is necessary. Before construction of a structure, to provide a suitable bed, different ways such as preloading, consoildation and appropriate additives are applied. In recent years, improvement of soil characteries using different additives are widely employed. In this study experimental program are conducted to investigate the effects of nano silica on creep behavior of soft clay soil. One-dimensional single stage and stepwise compression creep tests are conducted using standard oedometer apparatus under different stress levels on soft clay samples with different percentage of nano silica( 0.25, 0.5, 1 and 1.5٪ ). Creep mechanisms are explained based on relationship between coffecient of secondary compression and void ratio. Test results cleary indicate that the behavior of soft clay are affected of percentage of nano silica and stress levels. With increasing the nanosilica to specified level, the creep rate of samples decreases, and thus, the soil sample become denser. However more increase in ratio of nanosilica, porosity and coffecient of secondary compression decreases. On the other hand, it was observed that there is a nonlinear relation between the vertical stress level and coffecient of secondary compression. Also in stabilized samples with nanosilica, the values of compressibility index are smaller than samples without nanosilica. Of course with increasing the nanosilica to 0.5 weight percentage, due to soil resistance increament against settelment the compressibility index decreases, and with more increase weight percentage of nanosilica the compressibility index increases.

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