Review and Accuracy Comparison of Soil Pressure-Sinkage Models

Soil stiffness constants govern the soil sinkage and the behavior of soil under load. To determine the soil stiffness constants in Bekker and Upadhyaya models, a sandy-loam soil reflecting general character of an agricultural soil was selected and multiplate penetration tests were conducted. For each model, from the sinkage versus pressure relationship of the soil under different loads, the average soil stiffness constants k , k and n (corresponding to Bekker model) and k , k and n (corresponding to Upadhyaya model) were c 1 2 determined from the sets of three sinkage tests using three small rectangular plates that differ in plate width and having nearly the same area. Tests were replicated three times for each of the three small rectangular plates. Using the models and the calculated soil stiffness constants, the pressure-sinkage behavior of a large rectangular plate was predicted. The amounts of RMSE and MRPD pertaining to Bekker model prediction were 2 mm and 11.5%, respectively. The amounts of RMSE and MRPD pertaining to Upadhyaya model prediction were 2.5 mm and 13.25 %, respectively. The results of the study showed that when the soil stiffness constants are derived from tests on the three small rectangular plates, Bekker and Upadhyaya models can be used successfully to predict the soil pressure-sinkage behavior under a large rectangular plate about three times the width, however Bekker model, to some extent, shows better results. In addition, Bekker model under predicted the sinkage values, whereas Upadhyaya model over predicted the sinkage values.