Analysis of the behaviour of geogrid-anchored sheet pile walls

Abstract

Geogrids are commonly used for reinforcement of soils in construction of railway and road embankments and bridge abutments. A relatively new application of geogrids is the anchorage of sheet pile walls, in which one or more layers of geogrid are attached to the sheet pile wall. This type of anchorage is particularly suitable for projects with sufficient space behind the sheet pile wall. This anchorage system has some mayor advantages in comparison to conventional sheet pile wall anchors as it is cost-effective and requires less steel. Moreover, prestressing is possible during construction and pile foundations can be installed through the geogrids. An analytical design calculation method for this type of anchorage is not yet available in the Dutch design guideline for the design of sheet pile walls (CUR166). The demand for short anchorage systems because of the commonly limited space behind sheet pile walls, shifts the focus of the design to the minimum required length of the geogrid-anchorage.
This report makes a first step into the formulation of a design-calculation for the mobilised anchor resistance as a function of the length of the geogrid(s) at ultimate limit state. By means of a 1g small-scale physical model and a 2D finite element model (PLAXIS) of the small-scale physical model, the global failure mechanism and soil-geogrid interaction have been analysed. In a series of these experiments, an 18 cm long geogrid anchor was connected to a 30 cm high sheet pile wall and installed in sand in a small transparent test box and loaded with a strip footing load. In addition, experiments were conducted while varying several features, among which the number and length of the geogrid anchors and the location of the slip footing load.