New Mechanical Model for Evaluating Bearing Capacity of Prestressed Pipe Piles in Soil: Effect of Soil Layer

Because of the complexity of pile driving into different soil layers, the existing models fail to consider the effect of the soil layers. Thus, this paper develops a new mechanical model for predicting the bearing capacity of prestressed concrete pipe piles (PCPPs) while considering the influence of the soil layers. To this end, 12 PCPPs were constructed in the field for two types of experimental tests: the static load test (SLT) and the high-strain dynamic test (HSDT). The pile and soil properties, such as the settlement of the pile top, the cumulative deformation of the pile body, the side friction, the end bearing of the pile, and the damping coefficient, were measured or calculated. Then, a new mechanical model of the pile driving was proposed to include the influence of the types of the soil layer: sand, silt, silty clay, and highly weathered argillaceous siltstone. The corresponding calculation program based on the developed algo-rithm was compiled. Furthermore, the results of the SLT and the HSDT were then compared with the numerical data calculated by the developed model. The results demonstrate that the soil-layer type significantly impacts the pile-side or pile-end properties of the soil, such as the maximum elastic deformation and the damping coefficient. The new mechanical model of pile driving provides acceptable prediction data with a maximum difference of 15 % from the results of the SLT and the HSDT. Therefore, the mechanical model of pile driving is potentially useful for predicting the bearing capacity of prestressed pipe piles in the field.