INVESTIGATION AND COMPARISON OF MASHHAD'S CLAY AND SILTY SOILS CREEP BEHAVIOR

Creeping behavior of fine grained soils under constant loading over time is a significant subject in evaluating their behavior and the long-term settlements of foundations of the high rise buildings and lateral displacements of various retaining structures in contact of these soils. Grain soils often have no significant creeping behavior. This study, conducted on undisturbed samples of fine-grained soils of clay and silt from different parts of the city of Mashhad. By continuing constant loading over time consistent with the creep studies of a number of researchers, the changes of creeping coefficients were investigated after the main consolidation stage; in addition, the results of the secondary consolidation of the samples were evaluated and controlled by previous investigations. By using regression statistical analysis, the correlations of creep coefficients with other physical characteristic parameters of the fine grain samples has been evaluated. Studies on fine grained specimens in the city of Mashhad showed that they were mainly clay and silt with a low level of liquidity. In the statistical analysis of regression, the secondary consolidation coefficient and creep behavior of samples in the type of fine-grained clay CL with physical characteristic parameters of fine grained samples, especially with coefficient of compression, is more significant than the regression of ML fine-grained samples. Correlational equations have been analyzed and presented for both groups of local fine-grained soils. In addition, the results are compared with the limits of the proposed secondary compression coefficients of other researchers. The results can be used in predicting control and rapid calculations of creeping settlements, and displacements of high-rise structures, retaining structures, etc. in the city over time under constant load. For rapid initial calculations, without the need for results of long-term experiments, relationships of coefficients of creep behavior were obtained through regression analyses with other physical properties of fine grained material. The results of statistical analyzes for the clayey fine-grained soils have a more significant correlation with the physical properties of the soil than the fine-grained silts.