Permanent Sheet Pile Basement Wall

Today, sheet piles are used frequently in the construction of underground car parks and basements. Manufacturers are designing and installing a variety of sheet pile retaining walls according to the ground conditions and individual project requirements. Sheet pile walls can either be used in a temporary or permanent works application.

When sheet piles are used in permanent works, there is a possibility of achieving a high quality finish to such an extent that outward face of steel can be painted rather than building a concrete facing wall to place in front of the sheet piles. Sheet piles have been widely used in the construction of multiple underground car parks located within the basement structures and they have proved to be extremely efficient and cost effective.

Sheet pile walls when used as permanent structural elements in the construction of car parks or roads play multiple roles. A sheet pile wall :

  • Provides watertight containment for the excavation pit
  • Serves as the permanent outer structural wall
  • Serves as a retaining wall especially during the excavation phase in order to support the horizontal pressures better.

Sheet pile applications provide a number of benefits. Sheet pile walls can:

  • Maximise the available space, a highly needed feature especially in the urban centres
  • Shortens the overall construction time
  • Reduces the total cost of the project or building being constructed.

Sheet piles can be easily given a new look once the construction is complete with paint. Sheet pile application does not require a lot of time nor space for installation. Apart from providing water tightness during the excavation phase, sheet pile walls can also carry horizontal loads from earth pressures.

Sheet piles are usually delivered and used as welded double piles. Underground car park sheet piles are an extremely constructive component, shaped in a way that provides suitable depth below the floor of the excavation. Due to their exceptional benefits and help in rapid construction of the site, sheet piles today are used around the world in the construction of ports and harbours, bridge abutments, road widening retaining walls, flood defense system and river control structures.

(This article comes from ESC Pile editor released)

Advice on the use of FEM for retaining walls

2D/3D problem

Retaining wall structures are generally simulated with 2D equivalent models for FEM purposes (which is, of course, not possible with distinctly 3D problems such as the corners of excavations). Resolved structures such as struts, anchors, staggered sheet pile walls or bearing pile walls can be taken into account approximately in the 2D equivalent model but assuming equivalent stiffnesses related to a 1 m length of wall. Every individual case must be checked to ensure that the equivalent structure does not exhibit any unrealistic properties. Examples of this are: 2D equivalent anchors may not relieve the earth pressure acting on the retaining wall, 2D equivalent walls for staggered sheet pile walls may not be impermeable at the level of the staggered pile ends, 2D equivalent walls for bearing pile walls may not mobilise any unrealistically large passive earth pressures. It is not always clear whether all the deformations and stresses calculated with the 2D equivalent model are on the safe side; see (HÜGEL , 2004), for example. Examples of complex 3D analyses of sheet piling structures can be found in (BOLEY ET AL., 2004) and (M ARDFELDT, 2006).

Generalisation of the subsoil

Soil strata and groundwater conditions should be generalised in the finite element model depending on the database. However, when doing so, it must be ensured that the mechanical and hydraulic behaviour of the finite element model is comparable with the initial problem.

Subsoil segment and boundary conditions

The size of the subsoil segment should be specified such that the boundaries do not have any signi ficant effect on the deformations at the point of load transfer or such that the boundary conditions are known. Estimates of the dimensions necessary can be found in (MEISSNER, 2002) for the case of excavations.

Geometric non-linearity

Retaining wall structures are generally designed to be so stiff that finite element analyses may be based on geometric linearity. In the case of a yielding earth resistance and/or yielding anchorage, comparative analyses can be used to check whether geometric non-linearity needs to be taken into consideration.