الفهرس 
Soft Clay Soil Improvement and Stabilization
Geosynthetics Reinforcement in Roads and PavementsOnly 14 pages are availabe for public view
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Abstract
The national network of highways has been monotonically increased over the last few years. This network covers all the country and so some highways are needed to be constructed over soft clay soil. Soft clay soils have always been a great challenge in the field of geotechnical engineering when designing infrastructure. Because of low shear strength and high compressibility of this soil, many engineering problems such as slope instability, bearing capacity failure and excessive settlement could occur either during or after the construction phase. The design of highway pavement on soft clay soil still remains a very challenging issue, it often cause problems, such as roadbed instability or excessive settlement. As a result, soft soil roadbed treatment has become more and more important. The study aims at improving the clay soil by different methods to sustain suitable pavement section and its traffic loads.
The main objective of this research is to study the effect of the presence of soft clay on the structural design of pavement sections, and improving the soft clay by different methods to sustain suitable pavement section and its traffic loads.
To study several proposed scenarios for soil improvement and pavement sections, a small scale cyclic loading model device is manufactured to implement the paving layers and experiment it with a dynamically moving wheel to simulate what happens in nature.
In this study, quicklime is used to improve the properties of soil. The results showed that soil properties are significantly improved by using quicklime. By adding 7% quicklime to soft clay, the CBR value increased from 0.05 to 6.22%, and the modulus of compressibility increased from 129.84 to 502.37 kN/m2.
Geotextile is also used, and its utilization showed that it didn’t has significant effect on reducing the settlement of soft clay under pavement.
Geogrid is also used as a reinforcement of pavement sections. The use of geogrid enhances greatly the pavement to sustain the traffic load by reducing significantly the total settlement over a much longer operation time. It enhances the soft clay settlement and so the pavement strength by 89.77%.
The results showed that, the settlement achieved 120.05, 120.32 and 12.28 mm for natural soft clay, using geotextile and using geotextile with geogrid together, respectively. However, the settlement achieved 12, 7.21 and 3.49 mm for using quicklime, using quicklime with geotextile and using quicklime with geotextile & geogrid together, respectively.