Design of a single propped sheet pile walls

• Main Author: Wee, Joel Liang Shen.
• Other Authors: Goh Teck Chee, Anthony
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Civil engineering::Geotechnical
• Online Access: http://hdl.handle.net/10356/39524
• Institution: Nanyang Technological University

For the design of single propped walls, the free earth limit equilibrium method (LEM) assumes the wall to be infinitely rigid and does not consider the stiffness of the wall and the soil. This limits the understanding of how the stiffness of the wall and soil affects the wall maximum bending moments, the force in the strut and the earth pressures acting on the wall. In addition, wall deflection could not be determined. As technology advances, many geotechnical engineers use the finite element method (FEM) software such as PLAXIS, for their design. This project aims to study the effects on the behavior of sheet pile walls in sand supported by a single strut. Comparative studies were made between both LEM and FEM analysis. PLAXIS was used to analyze a total of 8 cases based on different properties and parameters such as depth of embedment, strength of the sand layer and stiffness of the wall and sand. Plane strain analysis was considered. The sand layer was modeled as drained analysis using the Hardening Soil Model. It was found that by increasing the embedment depth, the wall deflections, wall bending moments and force in the strut are reduced. The FEM analysis indicates that using a stiffer wall significantly reduces the wall deflections and bending moments but not the force in the strut. Soil arching was found to be present and the wall was found to be kicking in when the factor of safety on embedment depth is 1.5 times or larger. Design based on LEM analysis shows that no strut is required when the factor of safety on embedment depth is increased by 1.3 times or larger but this contrast with the FEM analysis. This project concluded that LEM analysis is less conservative than the FEM analysis. This is mainly due to LEM’s assumption of an infinitely rigid wall and its lack of consideration of the soil stiffness.