Study of Loose Soil Layer Effects on Excavations Supported by Steel Sheet Pile Walls – A Numerical Study

Abstract Steel sheet pile walls are being widely used in civil engineering projects for support systems. Soil is not uniform in depth, sometimes may be exit loose or soft soil layer in various depth. This issue can cause different effects on ground surface displacements, forces and moments acting on sheet piles and struts during excavation procedure, compared with status that soil is uniform in depth. This difference should be considered in design of sheet piles and struts. In this paper a deep excavation by using finite element method is analyzed. Excavation’s depth is divided to three layers. One of three layers is loose soil layer and its position is modeled in three different situations, top, middle and bottom. Obtained results are compared with excavation without loose layer. Pseudo static analysis is performed by applying 0.3g horizontal acceleration. Results show that existent of upper loose soil layer has negligible effects on vertical displacements sheet piles. Existent of loose clay layer beneath stiffer layers increases shear forces, lateral deformations and bending moments acting on sheet piles. Also middle loose layer changes maximum lateral deformation location of steel sheet pile wall.