Vertical Equilibrium of Sheet Pile Walls with Emphasis on Toe Capacity and Plugging

Constructions including retaining walls are normally established in areas where it is impossible to conduct an excavation with inclined sides. Due to large excavation depths and due to restrictions on the deformations of the wall, it is often necessary to anchor the wall. The limited space makes it impossible to design the anchorage with anchor plates, and the anchorage is therefore often designed as bored and injected soil anchors. Reasons for design and establishment make it is necessary to construct these anchors with an inclination. Inclining anchors imply that larger forces need to be transferred at the pile toe to fulfil vertical equilibrium. The paper describes a case study of sheet pile walls in Aalborg Clay, and the amount of loads transferred as point loads at the pile toe for free and anchored walls is estimated. A parametric study is made for the free wall with regards to the height and the roughness of the wall. Due to limitations of the calculation method, the study of the anchored wall only includes variation of the roughness. For the case study, it is found that the vertical equilibrium is fulfilled for the considered free wall. An anchored wall needs a plug forming at the pile toe to fulfil the criterion of vertical equilibrium. However, the suggested theoretical model shows that the extent of the plug is much smaller than needed.