Analysis of pile-soil interactions in expansive soils

Author: Khac Tuan Nguyen

Nguyen, Khac Tuan, 2021 Analysis of pile-soil interactions in expansive soils, Flinders University, College of Science and Engineering

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This study provides a simplified model to estimate the pile-soil interaction in expansive soil under axial loading with high accuracy compared with other complicated models.

Three methods can be used to predict the pile-soil interaction under the axial loading. Group 1 is the Simplified Analytical Method. This method is easy to apply. However, the results in terms of the vertical pile movement and the axial load are usually overestimated, and it is impossible to estimate the vertical soil movement. Group 2 is the Boundary Element Method, and Group 3 is the Finite Element Method. Those two methods offer accurate results but the theory behind them is intricate.

The present model uses a combination of theories in Group 1 and Group 2 so that it is easier to apply to interpret the following issues:

• The relationship between load and settlement (t-z curve).

• Vertical movements of pile and soil.

• Settlement of the pile head.

• Axial loads.

There is a good agreement between the present model with RS Pile results and other models. The model has the same interpretations for the pile-soil interaction under the axial loading:

• In the case of under only soil’s swelling pressure (no applied load), the pile and the surrounding soil move upwards due to the soil heave.

• As the applied load increases, the vertical pile movements, axial loads, settlement of the pile head, and vertical soil movements also increase.

• The pile-soil interaction is dependent on the distance between the pile axis to the calculated position. The larger distance, the smaller the downward movement of the pile and the surrounding soil. Those movements are inversely proportional to depth.

Keywords: Pile-soil interactions, axially loaded pile, pile-soil interaction in expansive soils, vertical pile movements, vertical soil movements.

Subject: Engineering thesis

Thesis type: Masters
Completed: 2021
School: College of Science and Engineering
Supervisor: Hongyu Qin