Using Genetic Programming to Predict (CPT) Soil Cohesion from Laboratory Tests Results

Abstract

Static cone penetration test (CPT) is a widely acceptable and reliable geotechnical in-situ tool that provides quick and truthful large amount of data about soil classification, stratification and properties. Undrained shear strength of clay (cu) is one of the main soil parameters that could be reasonably estimated from the CPT results, as it is directly correlated to the tip resistance through the empirical cone factor (Nk). During the last decades, several studies have been carried out to determine reliable values of the Nk factor that change with the variation of the soil type, nature and stress history conditions. Due to the movement of the construction activities in Egypt towards the east of Port Said region, located at the eastern side of the Nile Delta, and that is characterized, at some locations, with thick deposits of soft to very soft clays, to benefit from its unique location of high economic impact, extensive analyses have been carried out to define the reasonable value of the Nk factor for the prevailing clay at this zone. The performed study focused on using the genetic programming technique (GP) to determine a reliable correlation between the Nk value of east Port Said clay and the consistency limits that can be easily determined in the laboratory. Records of 102 sets of data gathered from the site investigation campaign carried out at the area under study and comprising CPT, U-U triaxial tests, unconfined compression tests, consistency limits and physical properties experiments, were used for the developed GP models.