Influence of corners in excavations on damage assessment

Raul Fuentes

doi:10.1680/jgere.18.00017

Abstract

This paper provides guidance on quantifying the extent of corner effects in excavations and their impact on damage assessment. The corner effects’ extent is of great importance in making early decisions during project planning and preliminary design, particularly in relation to stakeholder engagement and placement of instruments. By using empirical relations, one is able to provide an equation, validated against the literature and additional numerical models, for estimating the extent of corner effects for a particular excavation geometry. Furthermore, two more equations for quantifying the damage of excavations to adjacent structures are presented and validated against two case studies in the literature. The proposed equations are also useful in the context of early stages of project development. Finally, a simple study shows the different effects of corners in sections parallel and perpendicular to a retaining wall. This highlights that corner effects may actually induce additional damage due to the introduction of a movement gradient, as opposed to the common previous perception that assumed that they were always conservative as they reduced absolute movements.

Highlights

Corners affect the distribution of ground movements behind an excavation, as demonstrated extensively in the literature (e.g. Finno and Roboski, 2005; Finno et al, 2007; Fuentes and Devriendt, 2010; Hong et al, 2015; Hsiung et al, 2018; Lin et al, 2003; Moormann and Katzenbach, 2002; Ou et al, 2000; Roboski and Finno, 2006; Tan et al, 2014; Zradkovic et al, 2005)
This paper presents a short literature review of previous work where the impact of excavation geometry was considered in relation to corner effects
In the estimations of dmax, for excavations where L/H is greater than 4·0–6·0, and L/B is greater than 2·0–3·5

Summary

Introduction

Corners affect the distribution of ground movements behind an excavation, as demonstrated extensively in the literature (e.g. Finno and Roboski, 2005; Finno et al, 2007; Fuentes and Devriendt, 2010; Hong et al, 2015; Hsiung et al, 2018; Lin et al, 2003; Moormann and Katzenbach, 2002; Ou et al, 2000; Roboski and Finno, 2006; Tan et al, 2014; Zradkovic et al, 2005). Using validated published empirical methods, a relationship is derived and compared against case studies to show the extent of corner effects for different excavation geometries This expression is critical to allow a final presentation of a formulation that allows building damage assessment to be estimated very that can be used by practising engineers. Finno and Roboski (2005), through the use of the proposed function shown, inherently admit that a constant lateral movement of the wall (defined as plane strain) occurs in all cases. In order to have a consistent framework for comparison to cases from the literature, the author defines the distance to plane strain movements, x = dmax, as the distance from the corner of the excavation to the point where 90% of the maximum movement behind the wall occurs (see Figure 1). 0 0 0·5 1·0 1·5 2·0 2·5 3·0 3·5 4·0 4·5 5·0 5·5 6·0 6·5 7·0 7·5 8·0 8·5 9·0 9·5 10·0 L/H

90 D-wall 90 D-wall

90 Shell element

Á 8dmax pffiffiffi

Findings

Conclusions