Understanding the Responses of Surrounding Soils to Pile Setup from Medium-Scale Experiments and Cone Penetration Tests

Abstract

Four medium-scale experiments were conducted in a laboratory setting to better understand the responses of surrounding soil behaviors to the increase in pile resistance known as pile setup. Each experiment entailed compacting a soil profile consisting of cohesionless and/or cohesive soil in a large manhole and driving an instrumented steel pile model. Two experiments performed were entirely cohesive and cohesionless soil, and the other two experiments were conducted with mixed soil profiles simulating single and double drainage conditions. The surrounding soils were instrumented with piezometers and earth pressure cells to measure the pore water pressure and lateral earth pressure, respectively. Cone penetration tests (CPTs) were performed before driving and after static load tests to determine the change in soil properties as a result of pile setup. Alpha, Nordlund, and CPT analysis methods were used to estimate both shaft resistance and end bearing of the pile models. Results showed that pile setup occurred in cohesive layers, facilitated by drainage layers, and is contributed mainly from the gain in shaft resistance.