Study of Elastic Modulus of Alluvium Deposits in Southern Tehran

The results of over 100 geotechnical site investigations in different zones of Tehran alluvium in the south part of Tehran city were analyzed to determine the correlation of modulus between elasticity and SPT number of soil in southern Tehran alluvium. The alluvial deposits in southern Tehran are composed mostly of fine-grained materials or coarse-grained soils with silt and clay particles. Based on the soil material properties, the study area is divided into three sections. In each section, the results of a large number of in situ and laboratory tests are classified and analyzed to determine the elastic modulus of soil. The study shows that, for the first part of the area the modulus of elasticity from plate load test correlates well with SPT number and for the second and third parts, the direct shear and triaxial tests have an acceptable correlation with SPT number. Formulas relating elastic modulus to standard penetration test number are given and compared to those reported in the literature. Also, from the analysis of data it was seen that the elastic modulus of soil is increased with increase of maximum soil particles. Finally average results for unconfined strengths of fine grained soil in alluvium of the south of Tehran are presented.