Effects of 3D discrete soil nail inclusion on pull-out, with implications for design

Abstract

To reduce computational requirements, soil nail systems are usually modelled in finite elements as plane-strain models in which discrete nails are 'smeared' as continuous plates. The interaction of adjacent nails across horizontal spacing is assumed to be perfect. Intuitively, the interaction decreases as the spacing increases. A 3D study using a numerical pull-out model attempts to quantify the effect of various parameters on this effect, and hence provides guidelines for the zones of influence of nails according to finite element analysis. The guidelines provide an insight into the extent to which 2D plane-strain analysis is acceptable. The results are compared with numerical analyses from a single-row soil nail problem, and with case histories, to indicate the validity of the guidelines. © 2005 Thomas Telford Ltd.