Multiplate Penetration Tests to Determine Soil Stiffness Constants in Upadhyaya Model under Field Conditions

Soil stiffness constants govern the soil sinkage and the pressure-sinkage behaviour of the soil under load. To determine soil stiffness constants in Upadhyaya model under field conditions, a field reflecting general character of an agricultural soil was selected and multiplate penetration tests were conducted. The soil stiffness constants in Upadhyaya model were determined from five sets of soil pressure-sinkage tests using five rectangular plates that have the same contact area and different aspect ratio. The determined soil stiffness constants (k , k and n) for the experimental site were 222.3 kPa, 3635 kPa/m and 0.472, respectively. Although 1 2 for the risk of using the soil stiffness constants determined with tests that use only two plates, five different plates were used in this study, assessment of Upadhyaya model in predicting soil pressure-sinkage behaviour under field conditions is necessary before the model can be recommended for wider use.