Abstract—The subgrade must be able to support loads transmitted from the pavement structure. This load bearing capacity is often affected by degree of compaction, moisture content, and soil type. A subgrade that can support a high amount of loading without excessive deformation is considered good. The overall strength and performance of a pavement is dependent not only upon its design but also on the load-bearing capacity of the subgrade soil. Thus, anything that can be done to increase the load-bearing capacity (or structural support) of the subgrade soil will most likely improve the pavement load-bearing capacity and thus, pavement strength and performance. In this research five different fine grained soils were collected from different zone of Al Basrah city (60 samples from Al-zubar to Al-faw). Preliminary laboratory tests, such as grain size distribution, LL, and Plastic Limit (PL) were conducted in accordance with AASHTO specification. A total of 60 soil samples were prepared for CBR testing for socked and unsoaked soils. Soaked and unsoaked CBR models were developed considering various independent variables: swell index, optimum moisture content, maximum dry density, PH value, SO 3 % content and TSS% contents. The GIS tools are used in this research to manage the database and develop thematic maps for soil properties, liquid limit, plastic limit , CBR value, TTS content, maximum density and optimum water content.

Index Terms—CBR, Subgrade soil, GIS, Soaked and unsoaked, Regression model

Cite: Zainab Ahmad Abd Al Satar, Siham Idan Salih, Lubna Salih, and Najat Abd Al Razak, "CBR Prediction Model with GIS Application Technique," International Journal of Structural and Civil Engineering Research, Vol. 2, No. 2, pp. 1-8, May 2013.